1 /*
2 * Copyright (c) 1994, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package java.lang;
26
27 import java.io.BufferedInputStream;
28 import java.io.BufferedOutputStream;
29 import java.io.Console;
30 import java.io.FileDescriptor;
31 import java.io.FileInputStream;
32 import java.io.FileOutputStream;
33 import java.io.IOException;
34 import java.io.InputStream;
35 import java.io.OutputStream;
36 import java.io.PrintStream;
37 import java.lang.annotation.Annotation;
38 import java.lang.foreign.MemorySegment;
39 import java.lang.invoke.MethodHandle;
40 import java.lang.invoke.MethodType;
41 import java.lang.module.ModuleDescriptor;
42 import java.lang.reflect.ClassFileFormatVersion;
43 import java.lang.reflect.Executable;
44 import java.lang.reflect.Method;
45 import java.net.URI;
46 import java.nio.channels.Channel;
47 import java.nio.channels.spi.SelectorProvider;
48 import java.nio.charset.CharacterCodingException;
49 import java.nio.charset.Charset;
50 import java.security.ProtectionDomain;
51 import java.util.List;
52 import java.util.Locale;
53 import java.util.Map;
54 import java.util.Objects;
55 import java.util.Properties;
56 import java.util.ResourceBundle;
57 import java.util.Set;
58 import java.util.concurrent.Executor;
59 import java.util.concurrent.ScheduledExecutorService;
60 import java.util.function.Supplier;
61 import java.util.concurrent.ConcurrentHashMap;
62 import java.util.stream.Stream;
63
64 import jdk.internal.javac.Restricted;
65 import jdk.internal.loader.NativeLibraries;
66 import jdk.internal.logger.LoggerFinderLoader.TemporaryLoggerFinder;
67 import jdk.internal.misc.Blocker;
68 import jdk.internal.misc.CarrierThreadLocal;
69 import jdk.internal.util.StaticProperty;
70 import jdk.internal.module.ModuleBootstrap;
71 import jdk.internal.module.ServicesCatalog;
72 import jdk.internal.reflect.CallerSensitive;
73 import jdk.internal.reflect.Reflection;
74 import jdk.internal.access.JavaLangAccess;
75 import jdk.internal.access.SharedSecrets;
76 import jdk.internal.logger.LoggerFinderLoader;
77 import jdk.internal.logger.LazyLoggers;
78 import jdk.internal.logger.LocalizedLoggerWrapper;
79 import jdk.internal.misc.VM;
80 import jdk.internal.util.SystemProps;
81 import jdk.internal.vm.Continuation;
82 import jdk.internal.vm.ContinuationScope;
83 import jdk.internal.vm.StackableScope;
84 import jdk.internal.vm.ThreadContainer;
85 import jdk.internal.vm.annotation.IntrinsicCandidate;
86 import jdk.internal.vm.annotation.Stable;
87 import sun.reflect.annotation.AnnotationType;
88 import sun.nio.ch.Interruptible;
89 import sun.nio.cs.UTF_8;
90
91 /**
92 * The {@code System} class contains several useful class fields
93 * and methods. It cannot be instantiated.
94 *
95 * Among the facilities provided by the {@code System} class
96 * are standard input, standard output, and error output streams;
97 * access to externally defined properties and environment
98 * variables; a means of loading files and libraries; and a utility
99 * method for quickly copying a portion of an array.
100 *
101 * @since 1.0
102 */
103 public final class System {
104 /* Register the natives via the static initializer.
105 *
106 * The VM will invoke the initPhase1 method to complete the initialization
107 * of this class separate from <clinit>.
108 */
109 private static native void registerNatives();
110 static {
111 registerNatives();
112 }
113
114 /** Don't let anyone instantiate this class */
115 private System() {
116 }
117
118 /**
119 * The "standard" input stream. This stream is already
120 * open and ready to supply input data. This stream
121 * corresponds to keyboard input or another input source specified by
122 * the host environment or user. Applications should use the encoding
123 * specified by the {@link ##stdin.encoding stdin.encoding} property
124 * to convert input bytes to character data.
125 *
126 * @apiNote
127 * The typical approach to read character data is to wrap {@code System.in}
128 * within an {@link java.io.InputStreamReader InputStreamReader} or other object
129 * that handles character encoding. After this is done, subsequent reading should
130 * use only the wrapper object; operating directly on {@code System.in} results
131 * in unspecified behavior.
132 * <p>
133 * For handling interactive input, consider using {@link Console}.
134 *
135 * @see Console
136 * @see ##stdin.encoding stdin.encoding
137 */
138 public static final InputStream in = null;
139
140 /**
141 * The "standard" output stream. This stream is already
142 * open and ready to accept output data. Typically this stream
143 * corresponds to display output or another output destination
144 * specified by the host environment or user. The encoding used
145 * in the conversion from characters to bytes is equivalent to
146 * {@link ##stdout.encoding stdout.encoding}.
147 * <p>
148 * For simple stand-alone Java applications, a typical way to write
149 * a line of output data is:
150 * <blockquote><pre>
151 * System.out.println(data)
152 * </pre></blockquote>
153 * <p>
154 * See the {@code println} methods in class {@code PrintStream}.
155 *
156 * @see java.io.PrintStream#println()
157 * @see java.io.PrintStream#println(boolean)
158 * @see java.io.PrintStream#println(char)
159 * @see java.io.PrintStream#println(char[])
160 * @see java.io.PrintStream#println(double)
161 * @see java.io.PrintStream#println(float)
162 * @see java.io.PrintStream#println(int)
163 * @see java.io.PrintStream#println(long)
164 * @see java.io.PrintStream#println(java.lang.Object)
165 * @see java.io.PrintStream#println(java.lang.String)
166 * @see ##stdout.encoding stdout.encoding
167 */
168 public static final PrintStream out = null;
169
170 /**
171 * The "standard" error output stream. This stream is already
172 * open and ready to accept output data.
173 * <p>
174 * Typically this stream corresponds to display output or another
175 * output destination specified by the host environment or user. By
176 * convention, this output stream is used to display error messages
177 * or other information that should come to the immediate attention
178 * of a user even if the principal output stream, the value of the
179 * variable {@code out}, has been redirected to a file or other
180 * destination that is typically not continuously monitored.
181 * The encoding used in the conversion from characters to bytes is
182 * equivalent to {@link ##stderr.encoding stderr.encoding}.
183 *
184 * @see ##stderr.encoding stderr.encoding
185 */
186 public static final PrintStream err = null;
187
188 // Initial values of System.in and System.err, set in initPhase1().
189 private static @Stable InputStream initialIn;
190 private static @Stable PrintStream initialErr;
191
192 // `sun.jnu.encoding` if it is not supported. Otherwise null.
193 // It is initialized in `initPhase1()` before any charset providers
194 // are initialized.
195 private static String notSupportedJnuEncoding;
196
197 /**
198 * Reassigns the "standard" input stream.
199 *
200 * @param in the new standard input stream.
201 *
202 * @since 1.1
203 */
204 public static void setIn(InputStream in) {
205 setIn0(in);
206 }
207
208 /**
209 * Reassigns the "standard" output stream.
210 *
211 * @param out the new standard output stream
212 *
213 * @since 1.1
214 */
215 public static void setOut(PrintStream out) {
216 setOut0(out);
217 }
218
219 /**
220 * Reassigns the "standard" error output stream.
221 *
222 * @param err the new standard error output stream.
223 *
224 * @since 1.1
225 */
226 public static void setErr(PrintStream err) {
227 setErr0(err);
228 }
229
230 private static volatile Console cons;
231
232 /**
233 * Returns the unique {@link java.io.Console Console} object associated
234 * with the current Java virtual machine, if any.
235 *
236 * @return The system console, if any, otherwise {@code null}.
237 *
238 * @since 1.6
239 */
240 public static Console console() {
241 Console c;
242 if ((c = cons) == null) {
243 synchronized (System.class) {
244 if ((c = cons) == null) {
245 cons = c = SharedSecrets.getJavaIOAccess().console();
246 }
247 }
248 }
249 return c;
250 }
251
252 /**
253 * Returns the channel inherited from the entity that created this
254 * Java virtual machine.
255 *
256 * This method returns the channel obtained by invoking the
257 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
258 * inheritedChannel} method of the system-wide default
259 * {@link java.nio.channels.spi.SelectorProvider} object.
260 *
261 * <p> In addition to the network-oriented channels described in
262 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
263 * inheritedChannel}, this method may return other kinds of
264 * channels in the future.
265 *
266 * @return The inherited channel, if any, otherwise {@code null}.
267 *
268 * @throws IOException
269 * If an I/O error occurs
270 *
271 * @since 1.5
272 */
273 public static Channel inheritedChannel() throws IOException {
274 return SelectorProvider.provider().inheritedChannel();
275 }
276
277 private static native void setIn0(InputStream in);
278 private static native void setOut0(PrintStream out);
279 private static native void setErr0(PrintStream err);
280
281 /**
282 * Throws {@code UnsupportedOperationException}. Setting a security manager
283 * is not supported.
284 *
285 * @param sm ignored
286 * @throws UnsupportedOperationException always
287 * @see #getSecurityManager
288 * @deprecated This method originally set
289 * {@linkplain SecurityManager the system-wide Security Manager}.
290 * Setting a Security Manager is no longer supported. There is no
291 * replacement for the Security Manager or this method.
292 */
293 @Deprecated(since="17", forRemoval=true)
294 public static void setSecurityManager(@SuppressWarnings("removal") SecurityManager sm) {
295 throw new UnsupportedOperationException(
296 "Setting a Security Manager is not supported");
297 }
298
299 /**
300 * Returns {@code null}. Setting a security manager is not supported.
301 *
302 * @return {@code null}
303 * @see #setSecurityManager
304 * @deprecated This method originally returned
305 * {@linkplain SecurityManager the system-wide Security Manager}.
306 * Setting a Security Manager is no longer supported. There is no
307 * replacement for the Security Manager or this method.
308 */
309 @SuppressWarnings("removal")
310 @Deprecated(since="17", forRemoval=true)
311 public static SecurityManager getSecurityManager() {
312 return null;
313 }
314
315 /**
316 * Returns the current time in milliseconds. Note that
317 * while the unit of time of the return value is a millisecond,
318 * the granularity of the value depends on the underlying
319 * operating system and may be larger. For example, many
320 * operating systems measure time in units of tens of
321 * milliseconds.
322 *
323 * <p> See the description of the class {@code Date} for
324 * a discussion of slight discrepancies that may arise between
325 * "computer time" and coordinated universal time (UTC).
326 *
327 * @return the difference, measured in milliseconds, between
328 * the current time and midnight, January 1, 1970 UTC.
329 * @see java.util.Date
330 */
331 @IntrinsicCandidate
332 public static native long currentTimeMillis();
333
334 /**
335 * Returns the current value of the running Java Virtual Machine's
336 * high-resolution time source, in nanoseconds.
337 *
338 * This method can only be used to measure elapsed time and is
339 * not related to any other notion of system or wall-clock time.
340 * The value returned represents nanoseconds since some fixed but
341 * arbitrary <i>origin</i> time (perhaps in the future, so values
342 * may be negative). The same origin is used by all invocations of
343 * this method in an instance of a Java virtual machine; other
344 * virtual machine instances are likely to use a different origin.
345 *
346 * <p>This method provides nanosecond precision, but not necessarily
347 * nanosecond resolution (that is, how frequently the value changes)
348 * - no guarantees are made except that the resolution is at least as
349 * good as that of {@link #currentTimeMillis()}.
350 *
351 * <p>Differences in successive calls that span greater than
352 * approximately 292 years (2<sup>63</sup> nanoseconds) will not
353 * correctly compute elapsed time due to numerical overflow.
354 *
355 * <p>The values returned by this method become meaningful only when
356 * the difference between two such values, obtained within the same
357 * instance of a Java virtual machine, is computed.
358 *
359 * <p>For example, to measure how long some code takes to execute:
360 * <pre> {@code
361 * long startTime = System.nanoTime();
362 * // ... the code being measured ...
363 * long elapsedNanos = System.nanoTime() - startTime;}</pre>
364 *
365 * <p>To compare elapsed time against a timeout, use <pre> {@code
366 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
367 * instead of <pre> {@code
368 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
369 * because of the possibility of numerical overflow.
370 *
371 * @return the current value of the running Java Virtual Machine's
372 * high-resolution time source, in nanoseconds
373 * @since 1.5
374 */
375 @IntrinsicCandidate
376 public static native long nanoTime();
377
378 /**
379 * Copies an array from the specified source array, beginning at the
380 * specified position, to the specified position of the destination array.
381 * A subsequence of array components are copied from the source
382 * array referenced by {@code src} to the destination array
383 * referenced by {@code dest}. The number of components copied is
384 * equal to the {@code length} argument. The components at
385 * positions {@code srcPos} through
386 * {@code srcPos+length-1} in the source array are copied into
387 * positions {@code destPos} through
388 * {@code destPos+length-1}, respectively, of the destination
389 * array.
390 * <p>
391 * If the {@code src} and {@code dest} arguments refer to the
392 * same array object, then the copying is performed as if the
393 * components at positions {@code srcPos} through
394 * {@code srcPos+length-1} were first copied to a temporary
395 * array with {@code length} components and then the contents of
396 * the temporary array were copied into positions
397 * {@code destPos} through {@code destPos+length-1} of the
398 * destination array.
399 * <p>
400 * If {@code dest} is {@code null}, then a
401 * {@code NullPointerException} is thrown.
402 * <p>
403 * If {@code src} is {@code null}, then a
404 * {@code NullPointerException} is thrown and the destination
405 * array is not modified.
406 * <p>
407 * Otherwise, if any of the following is true, an
408 * {@code ArrayStoreException} is thrown and the destination is
409 * not modified:
410 * <ul>
411 * <li>The {@code src} argument refers to an object that is not an
412 * array.
413 * <li>The {@code dest} argument refers to an object that is not an
414 * array.
415 * <li>The {@code src} argument and {@code dest} argument refer
416 * to arrays whose component types are different primitive types.
417 * <li>The {@code src} argument refers to an array with a primitive
418 * component type and the {@code dest} argument refers to an array
419 * with a reference component type.
420 * <li>The {@code src} argument refers to an array with a reference
421 * component type and the {@code dest} argument refers to an array
422 * with a primitive component type.
423 * </ul>
424 * <p>
425 * Otherwise, if any of the following is true, an
426 * {@code IndexOutOfBoundsException} is
427 * thrown and the destination is not modified:
428 * <ul>
429 * <li>The {@code srcPos} argument is negative.
430 * <li>The {@code destPos} argument is negative.
431 * <li>The {@code length} argument is negative.
432 * <li>{@code srcPos+length} is greater than
433 * {@code src.length}, the length of the source array.
434 * <li>{@code destPos+length} is greater than
435 * {@code dest.length}, the length of the destination array.
436 * </ul>
437 * <p>
438 * Otherwise, if any actual component of the source array from
439 * position {@code srcPos} through
440 * {@code srcPos+length-1} cannot be converted to the component
441 * type of the destination array by assignment conversion, an
442 * {@code ArrayStoreException} is thrown. In this case, let
443 * <b><i>k</i></b> be the smallest nonnegative integer less than
444 * length such that {@code src[srcPos+}<i>k</i>{@code ]}
445 * cannot be converted to the component type of the destination
446 * array; when the exception is thrown, source array components from
447 * positions {@code srcPos} through
448 * {@code srcPos+}<i>k</i>{@code -1}
449 * will already have been copied to destination array positions
450 * {@code destPos} through
451 * {@code destPos+}<i>k</I>{@code -1} and no other
452 * positions of the destination array will have been modified.
453 * (Because of the restrictions already itemized, this
454 * paragraph effectively applies only to the situation where both
455 * arrays have component types that are reference types.)
456 *
457 * @param src the source array.
458 * @param srcPos starting position in the source array.
459 * @param dest the destination array.
460 * @param destPos starting position in the destination data.
461 * @param length the number of array elements to be copied.
462 * @throws IndexOutOfBoundsException if copying would cause
463 * access of data outside array bounds.
464 * @throws ArrayStoreException if an element in the {@code src}
465 * array could not be stored into the {@code dest} array
466 * because of a type mismatch.
467 * @throws NullPointerException if either {@code src} or
468 * {@code dest} is {@code null}.
469 */
470 @IntrinsicCandidate
471 public static native void arraycopy(Object src, int srcPos,
472 Object dest, int destPos,
473 int length);
474
475 /**
476 * Returns the same hash code for the given object as
477 * would be returned by the default method hashCode(),
478 * whether or not the given object's class overrides
479 * hashCode().
480 * The hash code for the null reference is zero.
481 *
482 * <div class="preview-block">
483 * <div class="preview-comment">
484 * The "identity hash code" of a {@linkplain Class#isValue() value object}
485 * is computed by combining the identity hash codes of the value object's fields recursively.
486 * </div>
487 * </div>
488 * @apiNote
489 * <div class="preview-block">
490 * <div class="preview-comment">
491 * Note that, like ==, this hash code exposes information about a value object's
492 * private fields that might otherwise be hidden by an identity object.
493 * Developers should be cautious about storing sensitive secrets in value object fields.
494 * </div>
495 * </div>
496 *
497 * @param x object for which the hashCode is to be calculated
498 * @return the hashCode
499 * @since 1.1
500 * @see Object#hashCode
501 * @see java.util.Objects#hashCode(Object)
502 */
503 @IntrinsicCandidate
504 public static native int identityHashCode(Object x);
505
506 /**
507 * System properties.
508 *
509 * See {@linkplain #getProperties getProperties} for details.
510 */
511 private static Properties props;
512
513 /**
514 * Determines the current system properties.
515 * <p>
516 * The current set of system properties for use by the
517 * {@link #getProperty(String)} method is returned as a
518 * {@code Properties} object. If there is no current set of
519 * system properties, a set of system properties is first created and
520 * initialized. This set of system properties includes a value
521 * for each of the following keys unless the description of the associated
522 * value indicates that the value is optional.
523 * <table class="striped" style="text-align:left">
524 * <caption style="display:none">Shows property keys and associated values</caption>
525 * <thead>
526 * <tr><th scope="col">Key</th>
527 * <th scope="col">Description of Associated Value</th></tr>
528 * </thead>
529 * <tbody>
530 * <tr><th scope="row">{@systemProperty java.version}</th>
531 * <td>Java Runtime Environment version, which may be interpreted
532 * as a {@link Runtime.Version}</td></tr>
533 * <tr><th scope="row">{@systemProperty java.version.date}</th>
534 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
535 * format, which may be interpreted as a {@link
536 * java.time.LocalDate}</td></tr>
537 * <tr><th scope="row">{@systemProperty java.vendor}</th>
538 * <td>Java Runtime Environment vendor</td></tr>
539 * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
540 * <td>Java vendor URL</td></tr>
541 * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
542 * <td>Java vendor version <em>(optional)</em> </td></tr>
543 * <tr><th scope="row">{@systemProperty java.home}</th>
544 * <td>Java installation directory</td></tr>
545 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
546 * <td>Java Virtual Machine specification version, whose value is the
547 * {@linkplain Runtime.Version#feature feature} element of the
548 * {@linkplain Runtime#version() runtime version}</td></tr>
549 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
550 * <td>Java Virtual Machine specification vendor</td></tr>
551 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
552 * <td>Java Virtual Machine specification name</td></tr>
553 * <tr><th scope="row">{@systemProperty java.vm.version}</th>
554 * <td>Java Virtual Machine implementation version which may be
555 * interpreted as a {@link Runtime.Version}</td></tr>
556 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
557 * <td>Java Virtual Machine implementation vendor</td></tr>
558 * <tr><th scope="row">{@systemProperty java.vm.name}</th>
559 * <td>Java Virtual Machine implementation name</td></tr>
560 * <tr><th scope="row">{@systemProperty java.specification.version}</th>
561 * <td>Java Runtime Environment specification version, whose value is
562 * the {@linkplain Runtime.Version#feature feature} element of the
563 * {@linkplain Runtime#version() runtime version}</td></tr>
564 * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
565 * <td>Java Runtime Environment specification maintenance version,
566 * may be interpreted as a positive integer <em>(optional, see below)</em></td></tr>
567 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
568 * <td>Java Runtime Environment specification vendor</td></tr>
569 * <tr><th scope="row">{@systemProperty java.specification.name}</th>
570 * <td>Java Runtime Environment specification name</td></tr>
571 * <tr><th scope="row">{@systemProperty java.class.version}</th>
572 * <td>{@linkplain java.lang.reflect.ClassFileFormatVersion#latest() Latest}
573 * Java class file format version recognized by the Java runtime as {@code "MAJOR.MINOR"}
574 * where {@link java.lang.reflect.ClassFileFormatVersion#major() MAJOR} and {@code MINOR}
575 * are both formatted as decimal integers</td></tr>
576 * <tr><th scope="row">{@systemProperty java.class.path}</th>
577 * <td>Java class path (refer to
578 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
579 * <tr><th scope="row">{@systemProperty java.library.path}</th>
580 * <td>List of paths to search when loading libraries</td></tr>
581 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
582 * <td>Default temp file path</td></tr>
583 * <tr><th scope="row">{@systemProperty os.name}</th>
584 * <td>Operating system name</td></tr>
585 * <tr><th scope="row">{@systemProperty os.arch}</th>
586 * <td>Operating system architecture</td></tr>
587 * <tr><th scope="row">{@systemProperty os.version}</th>
588 * <td>Operating system version</td></tr>
589 * <tr><th scope="row">{@systemProperty file.separator}</th>
590 * <td>File separator ("/" on UNIX)</td></tr>
591 * <tr><th scope="row">{@systemProperty path.separator}</th>
592 * <td>Path separator (":" on UNIX)</td></tr>
593 * <tr><th scope="row">{@systemProperty line.separator}</th>
594 * <td>Line separator ("\n" on UNIX)</td></tr>
595 * <tr><th scope="row">{@systemProperty user.name}</th>
596 * <td>User's account name</td></tr>
597 * <tr><th scope="row">{@systemProperty user.home}</th>
598 * <td>User's home directory</td></tr>
599 * <tr><th scope="row">{@systemProperty user.dir}</th>
600 * <td>User's current working directory</td></tr>
601 * <tr><th scope="row">{@systemProperty native.encoding}</th>
602 * <td>Character encoding name derived from the host environment and
603 * the user's settings. Setting this system property on the command line
604 * has no effect.</td></tr>
605 * <tr><th scope="row">{@systemProperty stdin.encoding}</th>
606 * <td>Character encoding name for {@link System#in System.in}.
607 * The Java runtime can be started with the system property set to {@code UTF-8}.
608 * Starting it with the property set to another value results in unspecified behavior.
609 * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
610 * <td>Character encoding name for {@link System#out System.out} and
611 * {@link System#console() System.console()}.
612 * The Java runtime can be started with the system property set to {@code UTF-8}.
613 * Starting it with the property set to another value results in unspecified behavior.
614 * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
615 * <td>Character encoding name for {@link System#err System.err}.
616 * The Java runtime can be started with the system property set to {@code UTF-8}.
617 * Starting it with the property set to another value results in unspecified behavior.
618 * </tbody>
619 * </table>
620 * <p>
621 * The {@code java.specification.maintenance.version} property is
622 * defined if the specification implemented by this runtime at the
623 * time of its construction had undergone a <a
624 * href="https://jcp.org/en/procedures/jcp2#3.6.4">maintenance
625 * release</a>. When defined, its value identifies that
626 * maintenance release. To indicate the first maintenance release
627 * this property will have the value {@code "1"}, to indicate the
628 * second maintenance release this property will have the value
629 * {@code "2"}, and so on.
630 * <p>
631 * Multiple paths in a system property value are separated by the path
632 * separator character of the platform.
633 * <p>
634 * Additional locale-related system properties defined by the
635 * {@link Locale##default_locale Default Locale} section in the {@code Locale}
636 * class description may also be obtained with this method.
637 *
638 * @apiNote
639 * <strong>Changing a standard system property may have unpredictable results
640 * unless otherwise specified.</strong>
641 * Property values may be cached during initialization or on first use.
642 * Setting a standard property after initialization using {@link #getProperties()},
643 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
644 * {@link #clearProperty(String)} may not have the desired effect.
645 *
646 * @implNote
647 * In addition to the standard system properties, the system
648 * properties may include the following keys:
649 * <table class="striped">
650 * <caption style="display:none">Shows property keys and associated values</caption>
651 * <thead>
652 * <tr><th scope="col">Key</th>
653 * <th scope="col">Description of Associated Value</th></tr>
654 * </thead>
655 * <tbody>
656 * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
657 * <td>The application module path</td></tr>
658 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
659 * <td>The upgrade module path</td></tr>
660 * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
661 * <td>The module name of the initial/main module</td></tr>
662 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
663 * <td>The main class name of the initial module</td></tr>
664 * <tr><th scope="row">{@systemProperty file.encoding}</th>
665 * <td>The name of the default charset, defaults to {@code UTF-8}.
666 * The property may be set on the command line to the value
667 * {@code UTF-8} or {@code COMPAT}. If set on the command line to
668 * the value {@code COMPAT} then the value is replaced with the
669 * value of the {@code native.encoding} property during startup.
670 * Setting the property to a value other than {@code UTF-8} or
671 * {@code COMPAT} results in unspecified behavior.
672 * </td></tr>
673 * </tbody>
674 * </table>
675 *
676 * @return the system properties
677 * @see #setProperties
678 * @see java.util.Properties
679 */
680 public static Properties getProperties() {
681 return props;
682 }
683
684 /**
685 * Returns the system-dependent line separator string. It always
686 * returns the same value - the initial value of the {@linkplain
687 * #getProperty(String) system property} {@code line.separator}.
688 *
689 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
690 * Windows systems it returns {@code "\r\n"}.
691 *
692 * @return the system-dependent line separator string
693 * @since 1.7
694 */
695 public static String lineSeparator() {
696 return lineSeparator;
697 }
698
699 private static String lineSeparator;
700
701 /**
702 * Sets the system properties to the {@code Properties} argument.
703 * <p>
704 * The argument becomes the current set of system properties for use
705 * by the {@link #getProperty(String)} method. If the argument is
706 * {@code null}, then the current set of system properties is
707 * forgotten.
708 *
709 * @apiNote
710 * <strong>Changing a standard system property may have unpredictable results
711 * unless otherwise specified</strong>.
712 * See {@linkplain #getProperties getProperties} for details.
713 *
714 * @param props the new system properties.
715 * @see #getProperties
716 * @see java.util.Properties
717 */
718 public static void setProperties(Properties props) {
719 if (props == null) {
720 Map<String, String> tempProps = SystemProps.initProperties();
721 VersionProps.init(tempProps);
722 props = createProperties(tempProps);
723 }
724 System.props = props;
725 }
726
727 /**
728 * Gets the system property indicated by the specified key.
729 * <p>
730 * If there is no current set of system properties, a set of system
731 * properties is first created and initialized in the same manner as
732 * for the {@code getProperties} method.
733 *
734 * @apiNote
735 * <strong>Changing a standard system property may have unpredictable results
736 * unless otherwise specified</strong>.
737 * See {@linkplain #getProperties getProperties} for details.
738 *
739 * @param key the name of the system property.
740 * @return the string value of the system property,
741 * or {@code null} if there is no property with that key.
742 *
743 * @throws NullPointerException if {@code key} is {@code null}.
744 * @throws IllegalArgumentException if {@code key} is empty.
745 * @see #setProperty
746 * @see java.lang.System#getProperties()
747 */
748 public static String getProperty(String key) {
749 checkKey(key);
750 return props.getProperty(key);
751 }
752
753 /**
754 * Gets the system property indicated by the specified key.
755 * <p>
756 * If there is no current set of system properties, a set of system
757 * properties is first created and initialized in the same manner as
758 * for the {@code getProperties} method.
759 *
760 * @param key the name of the system property.
761 * @param def a default value.
762 * @return the string value of the system property,
763 * or the default value if there is no property with that key.
764 *
765 * @throws NullPointerException if {@code key} is {@code null}.
766 * @throws IllegalArgumentException if {@code key} is empty.
767 * @see #setProperty
768 * @see java.lang.System#getProperties()
769 */
770 public static String getProperty(String key, String def) {
771 checkKey(key);
772 return props.getProperty(key, def);
773 }
774
775 /**
776 * Sets the system property indicated by the specified key.
777 *
778 * @apiNote
779 * <strong>Changing a standard system property may have unpredictable results
780 * unless otherwise specified</strong>.
781 * See {@linkplain #getProperties getProperties} for details.
782 *
783 * @param key the name of the system property.
784 * @param value the value of the system property.
785 * @return the previous value of the system property,
786 * or {@code null} if it did not have one.
787 *
788 * @throws NullPointerException if {@code key} or
789 * {@code value} is {@code null}.
790 * @throws IllegalArgumentException if {@code key} is empty.
791 * @see #getProperty
792 * @see java.lang.System#getProperty(java.lang.String)
793 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
794 * @since 1.2
795 */
796 public static String setProperty(String key, String value) {
797 checkKey(key);
798 return (String) props.setProperty(key, value);
799 }
800
801 /**
802 * Removes the system property indicated by the specified key.
803 *
804 * @apiNote
805 * <strong>Changing a standard system property may have unpredictable results
806 * unless otherwise specified</strong>.
807 * See {@linkplain #getProperties getProperties} method for details.
808 *
809 * @param key the name of the system property to be removed.
810 * @return the previous string value of the system property,
811 * or {@code null} if there was no property with that key.
812 *
813 * @throws NullPointerException if {@code key} is {@code null}.
814 * @throws IllegalArgumentException if {@code key} is empty.
815 * @see #getProperty
816 * @see #setProperty
817 * @see java.util.Properties
818 * @since 1.5
819 */
820 public static String clearProperty(String key) {
821 checkKey(key);
822 return (String) props.remove(key);
823 }
824
825 private static void checkKey(String key) {
826 if (key == null) {
827 throw new NullPointerException("key can't be null");
828 }
829 if (key.isEmpty()) {
830 throw new IllegalArgumentException("key can't be empty");
831 }
832 }
833
834 /**
835 * Gets the value of the specified environment variable. An
836 * environment variable is a system-dependent external named
837 * value.
838 *
839 * <p><a id="EnvironmentVSSystemProperties"><i>System
840 * properties</i> and <i>environment variables</i></a> are both
841 * conceptually mappings between names and values. Both
842 * mechanisms can be used to pass user-defined information to a
843 * Java process. Environment variables have a more global effect,
844 * because they are visible to all descendants of the process
845 * which defines them, not just the immediate Java subprocess.
846 * They can have subtly different semantics, such as case
847 * insensitivity, on different operating systems. For these
848 * reasons, environment variables are more likely to have
849 * unintended side effects. It is best to use system properties
850 * where possible. Environment variables should be used when a
851 * global effect is desired, or when an external system interface
852 * requires an environment variable (such as {@code PATH}).
853 *
854 * <p>On UNIX systems the alphabetic case of {@code name} is
855 * typically significant, while on Microsoft Windows systems it is
856 * typically not. For example, the expression
857 * {@code System.getenv("FOO").equals(System.getenv("foo"))}
858 * is likely to be true on Microsoft Windows.
859 *
860 * @param name the name of the environment variable
861 * @return the string value of the variable, or {@code null}
862 * if the variable is not defined in the system environment
863 * @throws NullPointerException if {@code name} is {@code null}
864 * @see #getenv()
865 * @see ProcessBuilder#environment()
866 */
867 public static String getenv(String name) {
868 return ProcessEnvironment.getenv(name);
869 }
870
871
872 /**
873 * Returns an unmodifiable string map view of the current system environment.
874 * The environment is a system-dependent mapping from names to
875 * values which is passed from parent to child processes.
876 *
877 * <p>If the system does not support environment variables, an
878 * empty map is returned.
879 *
880 * <p>The returned map will never contain null keys or values.
881 * Attempting to query the presence of a null key or value will
882 * throw a {@link NullPointerException}. Attempting to query
883 * the presence of a key or value which is not of type
884 * {@link String} will throw a {@link ClassCastException}.
885 *
886 * <p>The returned map and its collection views may not obey the
887 * general contract of the {@link Object#equals} and
888 * {@link Object#hashCode} methods.
889 *
890 * <p>The returned map is typically case-sensitive on all platforms.
891 *
892 * <p>When passing information to a Java subprocess,
893 * <a href=#EnvironmentVSSystemProperties>system properties</a>
894 * are generally preferred over environment variables.
895 *
896 * @return the environment as a map of variable names to values
897 * @see #getenv(String)
898 * @see ProcessBuilder#environment()
899 * @since 1.5
900 */
901 public static java.util.Map<String,String> getenv() {
902 return ProcessEnvironment.getenv();
903 }
904
905 /**
906 * {@code System.Logger} instances log messages that will be
907 * routed to the underlying logging framework the {@link System.LoggerFinder
908 * LoggerFinder} uses.
909 *
910 * {@code System.Logger} instances are typically obtained from
911 * the {@link java.lang.System System} class, by calling
912 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
913 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
914 * System.getLogger(loggerName, bundle)}.
915 *
916 * @see java.lang.System#getLogger(java.lang.String)
917 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
918 * @see java.lang.System.LoggerFinder
919 *
920 * @since 9
921 */
922 public interface Logger {
923
924 /**
925 * System {@linkplain Logger loggers} levels.
926 *
927 * A level has a {@linkplain #getName() name} and {@linkplain
928 * #getSeverity() severity}.
929 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
930 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
931 * by order of increasing severity.
932 * <br>
933 * {@link #ALL} and {@link #OFF}
934 * are simple markers with severities mapped respectively to
935 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
936 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
937 * <p>
938 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
939 * <p>
940 * {@linkplain System.Logger.Level System logger levels} are mapped to
941 * {@linkplain java.logging/java.util.logging.Level java.util.logging levels}
942 * of corresponding severity.
943 * <br>The mapping is as follows:
944 * <br><br>
945 * <table class="striped">
946 * <caption>System.Logger Severity Level Mapping</caption>
947 * <thead>
948 * <tr><th scope="col">System.Logger Levels</th>
949 * <th scope="col">java.util.logging Levels</th>
950 * </thead>
951 * <tbody>
952 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
953 * <td>{@link java.logging/java.util.logging.Level#ALL ALL}</td>
954 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
955 * <td>{@link java.logging/java.util.logging.Level#FINER FINER}</td>
956 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
957 * <td>{@link java.logging/java.util.logging.Level#FINE FINE}</td>
958 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
959 * <td>{@link java.logging/java.util.logging.Level#INFO INFO}</td>
960 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
961 * <td>{@link java.logging/java.util.logging.Level#WARNING WARNING}</td>
962 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
963 * <td>{@link java.logging/java.util.logging.Level#SEVERE SEVERE}</td>
964 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
965 * <td>{@link java.logging/java.util.logging.Level#OFF OFF}</td>
966 * </tbody>
967 * </table>
968 *
969 * @since 9
970 *
971 * @see java.lang.System.LoggerFinder
972 * @see java.lang.System.Logger
973 */
974 @SuppressWarnings("doclint:reference") // cross-module links
975 public enum Level {
976
977 // for convenience, we're reusing java.util.logging.Level int values
978 // the mapping logic in sun.util.logging.PlatformLogger depends
979 // on this.
980 /**
981 * A marker to indicate that all levels are enabled.
982 * This level {@linkplain #getSeverity() severity} is
983 * {@link Integer#MIN_VALUE}.
984 */
985 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
986 /**
987 * {@code TRACE} level: usually used to log diagnostic information.
988 * This level {@linkplain #getSeverity() severity} is
989 * {@code 400}.
990 */
991 TRACE(400), // typically mapped to/from j.u.l.Level.FINER
992 /**
993 * {@code DEBUG} level: usually used to log debug information traces.
994 * This level {@linkplain #getSeverity() severity} is
995 * {@code 500}.
996 */
997 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
998 /**
999 * {@code INFO} level: usually used to log information messages.
1000 * This level {@linkplain #getSeverity() severity} is
1001 * {@code 800}.
1002 */
1003 INFO(800), // typically mapped to/from j.u.l.Level.INFO
1004 /**
1005 * {@code WARNING} level: usually used to log warning messages.
1006 * This level {@linkplain #getSeverity() severity} is
1007 * {@code 900}.
1008 */
1009 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
1010 /**
1011 * {@code ERROR} level: usually used to log error messages.
1012 * This level {@linkplain #getSeverity() severity} is
1013 * {@code 1000}.
1014 */
1015 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
1016 /**
1017 * A marker to indicate that all levels are disabled.
1018 * This level {@linkplain #getSeverity() severity} is
1019 * {@link Integer#MAX_VALUE}.
1020 */
1021 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
1022
1023 private final int severity;
1024
1025 private Level(int severity) {
1026 this.severity = severity;
1027 }
1028
1029 /**
1030 * Returns the name of this level.
1031 * @return this level {@linkplain #name()}.
1032 */
1033 public final String getName() {
1034 return name();
1035 }
1036
1037 /**
1038 * Returns the severity of this level.
1039 * A higher severity means a more severe condition.
1040 * @return this level severity.
1041 */
1042 public final int getSeverity() {
1043 return severity;
1044 }
1045 }
1046
1047 /**
1048 * Returns the name of this logger.
1049 *
1050 * @return the logger name.
1051 */
1052 public String getName();
1053
1054 /**
1055 * Checks if a message of the given level would be logged by
1056 * this logger.
1057 *
1058 * @param level the log message level.
1059 * @return {@code true} if the given log message level is currently
1060 * being logged.
1061 *
1062 * @throws NullPointerException if {@code level} is {@code null}.
1063 */
1064 public boolean isLoggable(Level level);
1065
1066 /**
1067 * Logs a message.
1068 *
1069 * @implSpec The default implementation for this method calls
1070 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1071 *
1072 * @param level the log message level.
1073 * @param msg the string message (or a key in the message catalog, if
1074 * this logger is a {@link
1075 * LoggerFinder#getLocalizedLogger(java.lang.String,
1076 * java.util.ResourceBundle, java.lang.Module) localized logger});
1077 * can be {@code null}.
1078 *
1079 * @throws NullPointerException if {@code level} is {@code null}.
1080 */
1081 public default void log(Level level, String msg) {
1082 log(level, (ResourceBundle) null, msg, (Object[]) null);
1083 }
1084
1085 /**
1086 * Logs a lazily supplied message.
1087 *
1088 * If the logger is currently enabled for the given log message level
1089 * then a message is logged that is the result produced by the
1090 * given supplier function. Otherwise, the supplier is not operated on.
1091 *
1092 * @implSpec When logging is enabled for the given level, the default
1093 * implementation for this method calls
1094 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
1095 *
1096 * @param level the log message level.
1097 * @param msgSupplier a supplier function that produces a message.
1098 *
1099 * @throws NullPointerException if {@code level} is {@code null},
1100 * or {@code msgSupplier} is {@code null}.
1101 */
1102 public default void log(Level level, Supplier<String> msgSupplier) {
1103 Objects.requireNonNull(msgSupplier);
1104 if (isLoggable(Objects.requireNonNull(level))) {
1105 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1106 }
1107 }
1108
1109 /**
1110 * Logs a message produced from the given object.
1111 *
1112 * If the logger is currently enabled for the given log message level then
1113 * a message is logged that, by default, is the result produced from
1114 * calling toString on the given object.
1115 * Otherwise, the object is not operated on.
1116 *
1117 * @implSpec When logging is enabled for the given level, the default
1118 * implementation for this method calls
1119 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1120 *
1121 * @param level the log message level.
1122 * @param obj the object to log.
1123 *
1124 * @throws NullPointerException if {@code level} is {@code null}, or
1125 * {@code obj} is {@code null}.
1126 */
1127 public default void log(Level level, Object obj) {
1128 Objects.requireNonNull(obj);
1129 if (isLoggable(Objects.requireNonNull(level))) {
1130 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1131 }
1132 }
1133
1134 /**
1135 * Logs a message associated with a given throwable.
1136 *
1137 * @implSpec The default implementation for this method calls
1138 * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1139 *
1140 * @param level the log message level.
1141 * @param msg the string message (or a key in the message catalog, if
1142 * this logger is a {@link
1143 * LoggerFinder#getLocalizedLogger(java.lang.String,
1144 * java.util.ResourceBundle, java.lang.Module) localized logger});
1145 * can be {@code null}.
1146 * @param thrown a {@code Throwable} associated with the log message;
1147 * can be {@code null}.
1148 *
1149 * @throws NullPointerException if {@code level} is {@code null}.
1150 */
1151 public default void log(Level level, String msg, Throwable thrown) {
1152 this.log(level, null, msg, thrown);
1153 }
1154
1155 /**
1156 * Logs a lazily supplied message associated with a given throwable.
1157 *
1158 * If the logger is currently enabled for the given log message level
1159 * then a message is logged that is the result produced by the
1160 * given supplier function. Otherwise, the supplier is not operated on.
1161 *
1162 * @implSpec When logging is enabled for the given level, the default
1163 * implementation for this method calls
1164 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1165 *
1166 * @param level one of the log message level identifiers.
1167 * @param msgSupplier a supplier function that produces a message.
1168 * @param thrown a {@code Throwable} associated with log message;
1169 * can be {@code null}.
1170 *
1171 * @throws NullPointerException if {@code level} is {@code null}, or
1172 * {@code msgSupplier} is {@code null}.
1173 */
1174 public default void log(Level level, Supplier<String> msgSupplier,
1175 Throwable thrown) {
1176 Objects.requireNonNull(msgSupplier);
1177 if (isLoggable(Objects.requireNonNull(level))) {
1178 this.log(level, null, msgSupplier.get(), thrown);
1179 }
1180 }
1181
1182 /**
1183 * Logs a message with an optional list of parameters.
1184 *
1185 * @implSpec The default implementation for this method calls
1186 * {@code this.log(level, (ResourceBundle)null, format, params);}
1187 *
1188 * @param level one of the log message level identifiers.
1189 * @param format the string message format in {@link
1190 * java.text.MessageFormat} format, (or a key in the message
1191 * catalog, if this logger is a {@link
1192 * LoggerFinder#getLocalizedLogger(java.lang.String,
1193 * java.util.ResourceBundle, java.lang.Module) localized logger});
1194 * can be {@code null}.
1195 * @param params an optional list of parameters to the message (may be
1196 * none).
1197 *
1198 * @throws NullPointerException if {@code level} is {@code null}.
1199 */
1200 public default void log(Level level, String format, Object... params) {
1201 this.log(level, null, format, params);
1202 }
1203
1204 /**
1205 * Logs a localized message associated with a given throwable.
1206 *
1207 * If the given resource bundle is non-{@code null}, the {@code msg}
1208 * string is localized using the given resource bundle.
1209 * Otherwise the {@code msg} string is not localized.
1210 *
1211 * @param level the log message level.
1212 * @param bundle a resource bundle to localize {@code msg}; can be
1213 * {@code null}.
1214 * @param msg the string message (or a key in the message catalog,
1215 * if {@code bundle} is not {@code null}); can be {@code null}.
1216 * @param thrown a {@code Throwable} associated with the log message;
1217 * can be {@code null}.
1218 *
1219 * @throws NullPointerException if {@code level} is {@code null}.
1220 */
1221 public void log(Level level, ResourceBundle bundle, String msg,
1222 Throwable thrown);
1223
1224 /**
1225 * Logs a message with resource bundle and an optional list of
1226 * parameters.
1227 *
1228 * If the given resource bundle is non-{@code null}, the {@code format}
1229 * string is localized using the given resource bundle.
1230 * Otherwise the {@code format} string is not localized.
1231 *
1232 * @param level the log message level.
1233 * @param bundle a resource bundle to localize {@code format}; can be
1234 * {@code null}.
1235 * @param format the string message format in {@link
1236 * java.text.MessageFormat} format, (or a key in the message
1237 * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1238 * @param params an optional list of parameters to the message (may be
1239 * none).
1240 *
1241 * @throws NullPointerException if {@code level} is {@code null}.
1242 */
1243 public void log(Level level, ResourceBundle bundle, String format,
1244 Object... params);
1245 }
1246
1247 /**
1248 * The {@code LoggerFinder} service is responsible for creating, managing,
1249 * and configuring loggers to the underlying framework it uses.
1250 *
1251 * A logger finder is a concrete implementation of this class that has a
1252 * zero-argument constructor and implements the abstract methods defined
1253 * by this class.
1254 * The loggers returned from a logger finder are capable of routing log
1255 * messages to the logging backend this provider supports.
1256 * A given invocation of the Java Runtime maintains a single
1257 * system-wide LoggerFinder instance that is loaded as follows:
1258 * <ul>
1259 * <li>First it finds any custom {@code LoggerFinder} provider
1260 * using the {@link java.util.ServiceLoader} facility with the
1261 * {@linkplain ClassLoader#getSystemClassLoader() system class
1262 * loader}.</li>
1263 * <li>If no {@code LoggerFinder} provider is found, the system default
1264 * {@code LoggerFinder} implementation will be used.</li>
1265 * </ul>
1266 * <p>
1267 * An application can replace the logging backend
1268 * <i>even when the java.logging module is present</i>, by simply providing
1269 * and declaring an implementation of the {@link LoggerFinder} service.
1270 * <p>
1271 * <b>Default Implementation</b>
1272 * <p>
1273 * The system default {@code LoggerFinder} implementation uses
1274 * {@code java.util.logging} as the backend framework when the
1275 * {@code java.logging} module is present.
1276 * It returns a {@linkplain System.Logger logger} instance
1277 * that will route log messages to a {@link java.logging/java.util.logging.Logger
1278 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1279 * present, the default implementation will return a simple logger
1280 * instance that will route log messages of {@code INFO} level and above to
1281 * the console ({@code System.err}).
1282 * <p>
1283 * <b>Logging Configuration</b>
1284 * <p>
1285 * {@linkplain Logger Logger} instances obtained from the
1286 * {@code LoggerFinder} factory methods are not directly configurable by
1287 * the application. Configuration is the responsibility of the underlying
1288 * logging backend, and usually requires using APIs specific to that backend.
1289 * <p>For the default {@code LoggerFinder} implementation
1290 * using {@code java.util.logging} as its backend, refer to
1291 * {@link java.logging/java.util.logging java.util.logging} for logging configuration.
1292 * For the default {@code LoggerFinder} implementation returning simple loggers
1293 * when the {@code java.logging} module is absent, the configuration
1294 * is implementation dependent.
1295 * <p>
1296 * Usually an application that uses a logging framework will log messages
1297 * through a logger facade defined (or supported) by that framework.
1298 * Applications that wish to use an external framework should log
1299 * through the facade associated with that framework.
1300 * <p>
1301 * A system class that needs to log messages will typically obtain
1302 * a {@link System.Logger} instance to route messages to the logging
1303 * framework selected by the application.
1304 * <p>
1305 * Libraries and classes that only need loggers to produce log messages
1306 * should not attempt to configure loggers by themselves, as that
1307 * would make them dependent from a specific implementation of the
1308 * {@code LoggerFinder} service.
1309 * <p>
1310 * <b>Message Levels and Mapping to backend levels</b>
1311 * <p>
1312 * A logger finder is responsible for mapping from a {@code
1313 * System.Logger.Level} to a level supported by the logging backend it uses.
1314 * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1315 * maps {@code System.Logger} levels to
1316 * {@linkplain java.logging/java.util.logging.Level java.util.logging} levels
1317 * of corresponding severity - as described in {@link Logger.Level
1318 * Logger.Level}.
1319 *
1320 * @see java.lang.System
1321 * @see java.lang.System.Logger
1322 *
1323 * @since 9
1324 */
1325 @SuppressWarnings("doclint:reference") // cross-module links
1326 public abstract static class LoggerFinder {
1327
1328 /**
1329 * Creates a new instance of {@code LoggerFinder}.
1330 *
1331 * @implNote It is recommended that a {@code LoggerFinder} service
1332 * implementation does not perform any heavy initialization in its
1333 * constructor, in order to avoid possible risks of deadlock or class
1334 * loading cycles during the instantiation of the service provider.
1335 */
1336 protected LoggerFinder() {
1337 }
1338
1339 /**
1340 * Returns an instance of {@link Logger Logger}
1341 * for the given {@code module}.
1342 *
1343 * @param name the name of the logger.
1344 * @param module the module for which the logger is being requested.
1345 *
1346 * @return a {@link Logger logger} suitable for use within the given
1347 * module.
1348 * @throws NullPointerException if {@code name} is {@code null} or
1349 * {@code module} is {@code null}.
1350 */
1351 public abstract Logger getLogger(String name, Module module);
1352
1353 /**
1354 * Returns a localizable instance of {@link Logger Logger}
1355 * for the given {@code module}.
1356 * The returned logger will use the provided resource bundle for
1357 * message localization.
1358 *
1359 * @implSpec By default, this method calls {@link
1360 * #getLogger(java.lang.String, java.lang.Module)
1361 * this.getLogger(name, module)} to obtain a logger, then wraps that
1362 * logger in a {@link Logger} instance where all methods that do not
1363 * take a {@link ResourceBundle} as parameter are redirected to one
1364 * which does - passing the given {@code bundle} for
1365 * localization. So for instance, a call to {@link
1366 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1367 * will end up as a call to {@link
1368 * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1369 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1370 * logger instance.
1371 * Note however that by default, string messages returned by {@link
1372 * java.util.function.Supplier Supplier<String>} will not be
1373 * localized, as it is assumed that such strings are messages which are
1374 * already constructed, rather than keys in a resource bundle.
1375 * <p>
1376 * An implementation of {@code LoggerFinder} may override this method,
1377 * for example, when the underlying logging backend provides its own
1378 * mechanism for localizing log messages, then such a
1379 * {@code LoggerFinder} would be free to return a logger
1380 * that makes direct use of the mechanism provided by the backend.
1381 *
1382 * @param name the name of the logger.
1383 * @param bundle a resource bundle; can be {@code null}.
1384 * @param module the module for which the logger is being requested.
1385 * @return an instance of {@link Logger Logger} which will use the
1386 * provided resource bundle for message localization.
1387 *
1388 * @throws NullPointerException if {@code name} is {@code null} or
1389 * {@code module} is {@code null}.
1390 */
1391 public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1392 Module module) {
1393 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1394 }
1395
1396 /**
1397 * Returns the {@code LoggerFinder} instance. There is one
1398 * single system-wide {@code LoggerFinder} instance in
1399 * the Java Runtime. See the class specification of how the
1400 * {@link LoggerFinder LoggerFinder} implementation is located and
1401 * loaded.
1402 *
1403 * @return the {@link LoggerFinder LoggerFinder} instance.
1404 */
1405 public static LoggerFinder getLoggerFinder() {
1406 return accessProvider();
1407 }
1408
1409
1410 private static volatile LoggerFinder service;
1411 static LoggerFinder accessProvider() {
1412 // We do not need to synchronize: LoggerFinderLoader will
1413 // always return the same instance, so if we don't have it,
1414 // just fetch it again.
1415 LoggerFinder finder = service;
1416 if (finder == null) {
1417 finder = LoggerFinderLoader.getLoggerFinder();
1418 if (finder instanceof TemporaryLoggerFinder) return finder;
1419 service = finder;
1420 }
1421 return finder;
1422 }
1423
1424 }
1425
1426
1427 /**
1428 * Returns an instance of {@link Logger Logger} for the caller's
1429 * use.
1430 *
1431 * @implSpec
1432 * Instances returned by this method route messages to loggers
1433 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1434 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1435 * {@code module} is the caller's module.
1436 * In cases where {@code System.getLogger} is called from a context where
1437 * there is no caller frame on the stack (e.g when called directly
1438 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1439 * To obtain a logger in such a context, use an auxiliary class that will
1440 * implicitly be identified as the caller, or use the system {@link
1441 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1442 * Note that doing the latter may eagerly initialize the underlying
1443 * logging system.
1444 *
1445 * @apiNote
1446 * This method may defer calling the {@link
1447 * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1448 * LoggerFinder.getLogger} method to create an actual logger supplied by
1449 * the logging backend, for instance, to allow loggers to be obtained during
1450 * the system initialization time.
1451 *
1452 * @param name the name of the logger.
1453 * @return an instance of {@link Logger} that can be used by the calling
1454 * class.
1455 * @throws NullPointerException if {@code name} is {@code null}.
1456 * @throws IllegalCallerException if there is no Java caller frame on the
1457 * stack.
1458 *
1459 * @since 9
1460 */
1461 @CallerSensitive
1462 public static Logger getLogger(String name) {
1463 Objects.requireNonNull(name);
1464 final Class<?> caller = Reflection.getCallerClass();
1465 if (caller == null) {
1466 throw new IllegalCallerException("no caller frame");
1467 }
1468 return LazyLoggers.getLogger(name, caller.getModule());
1469 }
1470
1471 /**
1472 * Returns a localizable instance of {@link Logger
1473 * Logger} for the caller's use.
1474 * The returned logger will use the provided resource bundle for message
1475 * localization.
1476 *
1477 * @implSpec
1478 * The returned logger will perform message localization as specified
1479 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1480 * java.util.ResourceBundle, java.lang.Module)
1481 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1482 * {@code module} is the caller's module.
1483 * In cases where {@code System.getLogger} is called from a context where
1484 * there is no caller frame on the stack (e.g when called directly
1485 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1486 * To obtain a logger in such a context, use an auxiliary class that
1487 * will implicitly be identified as the caller, or use the system {@link
1488 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1489 * Note that doing the latter may eagerly initialize the underlying
1490 * logging system.
1491 *
1492 * @apiNote
1493 * This method is intended to be used after the system is fully initialized.
1494 * This method may trigger the immediate loading and initialization
1495 * of the {@link LoggerFinder} service, which may cause issues if the
1496 * Java Runtime is not ready to initialize the concrete service
1497 * implementation yet.
1498 * System classes which may be loaded early in the boot sequence and
1499 * need to log localized messages should create a logger using
1500 * {@link #getLogger(java.lang.String)} and then use the log methods that
1501 * take a resource bundle as parameter.
1502 *
1503 * @param name the name of the logger.
1504 * @param bundle a resource bundle.
1505 * @return an instance of {@link Logger} which will use the provided
1506 * resource bundle for message localization.
1507 * @throws NullPointerException if {@code name} is {@code null} or
1508 * {@code bundle} is {@code null}.
1509 * @throws IllegalCallerException if there is no Java caller frame on the
1510 * stack.
1511 *
1512 * @since 9
1513 */
1514 @CallerSensitive
1515 public static Logger getLogger(String name, ResourceBundle bundle) {
1516 final ResourceBundle rb = Objects.requireNonNull(bundle);
1517 Objects.requireNonNull(name);
1518 final Class<?> caller = Reflection.getCallerClass();
1519 if (caller == null) {
1520 throw new IllegalCallerException("no caller frame");
1521 }
1522 return LoggerFinder.accessProvider()
1523 .getLocalizedLogger(name, rb, caller.getModule());
1524 }
1525
1526 /**
1527 * Initiates the {@linkplain Runtime##shutdown shutdown sequence} of the Java Virtual
1528 * Machine. This method initiates the shutdown sequence (if it is not already initiated)
1529 * and then blocks indefinitely. This method neither returns nor throws an exception;
1530 * that is, it does not complete either normally or abruptly.
1531 * <p>
1532 * The argument serves as a status code. By convention, a nonzero status code
1533 * indicates abnormal termination.
1534 * <p>
1535 * The call {@code System.exit(n)} is effectively equivalent to the call:
1536 * {@snippet :
1537 * Runtime.getRuntime().exit(n)
1538 * }
1539 *
1540 * @implNote
1541 * The initiation of the shutdown sequence is logged by {@link Runtime#exit(int)}.
1542 *
1543 * @param status exit status.
1544 * @see java.lang.Runtime#exit(int)
1545 */
1546 public static void exit(int status) {
1547 Runtime.getRuntime().exit(status);
1548 }
1549
1550 /**
1551 * Runs the garbage collector in the Java Virtual Machine.
1552 * <p>
1553 * Calling the {@code gc} method suggests that the Java Virtual Machine
1554 * expend effort toward recycling unused objects in order to
1555 * make the memory they currently occupy available for reuse
1556 * by the Java Virtual Machine.
1557 * When control returns from the method call, the Java Virtual Machine
1558 * has made a best effort to reclaim space from all unused objects.
1559 * There is no guarantee that this effort will recycle any particular
1560 * number of unused objects, reclaim any particular amount of space, or
1561 * complete at any particular time, if at all, before the method returns or ever.
1562 * There is also no guarantee that this effort will determine
1563 * the change of reachability in any particular number of objects,
1564 * or that any particular number of {@link java.lang.ref.Reference Reference}
1565 * objects will be cleared and enqueued.
1566 *
1567 * <p>
1568 * The call {@code System.gc()} is effectively equivalent to the
1569 * call:
1570 * <blockquote><pre>
1571 * Runtime.getRuntime().gc()
1572 * </pre></blockquote>
1573 *
1574 * @see java.lang.Runtime#gc()
1575 */
1576 public static void gc() {
1577 Runtime.getRuntime().gc();
1578 }
1579
1580 /**
1581 * Runs the finalization methods of any objects pending finalization.
1582 *
1583 * Calling this method suggests that the Java Virtual Machine expend
1584 * effort toward running the {@code finalize} methods of objects
1585 * that have been found to be discarded but whose {@code finalize}
1586 * methods have not yet been run. When control returns from the
1587 * method call, the Java Virtual Machine has made a best effort to
1588 * complete all outstanding finalizations.
1589 * <p>
1590 * The call {@code System.runFinalization()} is effectively
1591 * equivalent to the call:
1592 * <blockquote><pre>
1593 * Runtime.getRuntime().runFinalization()
1594 * </pre></blockquote>
1595 *
1596 * @deprecated Finalization has been deprecated for removal. See
1597 * {@link java.lang.Object#finalize} for background information and details
1598 * about migration options.
1599 * <p>
1600 * When running in a JVM in which finalization has been disabled or removed,
1601 * no objects will be pending finalization, so this method does nothing.
1602 *
1603 * @see java.lang.Runtime#runFinalization()
1604 * @jls 12.6 Finalization of Class Instances
1605 */
1606 @Deprecated(since="18", forRemoval=true)
1607 @SuppressWarnings("removal")
1608 public static void runFinalization() {
1609 Runtime.getRuntime().runFinalization();
1610 }
1611
1612 /**
1613 * Loads the native library specified by the filename argument. The filename
1614 * argument must be an absolute path name.
1615 *
1616 * If the filename argument, when stripped of any platform-specific library
1617 * prefix, path, and file extension, indicates a library whose name is,
1618 * for example, L, and a native library called L is statically linked
1619 * with the VM, then the JNI_OnLoad_L function exported by the library
1620 * is invoked rather than attempting to load a dynamic library.
1621 * A filename matching the argument does not have to exist in the
1622 * file system.
1623 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1624 * for more details.
1625 *
1626 * Otherwise, the filename argument is mapped to a native library image in
1627 * an implementation-dependent manner.
1628 *
1629 * <p>
1630 * The call {@code System.load(name)} is effectively equivalent
1631 * to the call:
1632 * <blockquote><pre>
1633 * Runtime.getRuntime().load(name)
1634 * </pre></blockquote>
1635 *
1636 * @param filename the file to load.
1637 * @throws UnsatisfiedLinkError if either the filename is not an
1638 * absolute path name, the native library is not statically
1639 * linked with the VM, or the library cannot be mapped to
1640 * a native library image by the host system.
1641 * @throws NullPointerException if {@code filename} is {@code null}
1642 * @throws IllegalCallerException if the caller is in a module that
1643 * does not have native access enabled.
1644 *
1645 * @spec jni/index.html Java Native Interface Specification
1646 * @see java.lang.Runtime#load(java.lang.String)
1647 */
1648 @CallerSensitive
1649 @Restricted
1650 public static void load(String filename) {
1651 Class<?> caller = Reflection.getCallerClass();
1652 Reflection.ensureNativeAccess(caller, System.class, "load", false);
1653 Runtime.getRuntime().load0(caller, filename);
1654 }
1655
1656 /**
1657 * Loads the native library specified by the {@code libname}
1658 * argument. The {@code libname} argument must not contain any platform
1659 * specific prefix, file extension or path. If a native library
1660 * called {@code libname} is statically linked with the VM, then the
1661 * JNI_OnLoad_{@code libname} function exported by the library is invoked.
1662 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1663 * for more details.
1664 *
1665 * Otherwise, the libname argument is loaded from a system library
1666 * location and mapped to a native library image in an
1667 * implementation-dependent manner.
1668 * <p>
1669 * The call {@code System.loadLibrary(name)} is effectively
1670 * equivalent to the call
1671 * <blockquote><pre>
1672 * Runtime.getRuntime().loadLibrary(name)
1673 * </pre></blockquote>
1674 *
1675 * @param libname the name of the library.
1676 * @throws UnsatisfiedLinkError if either the libname argument
1677 * contains a file path, the native library is not statically
1678 * linked with the VM, or the library cannot be mapped to a
1679 * native library image by the host system.
1680 * @throws NullPointerException if {@code libname} is {@code null}
1681 * @throws IllegalCallerException if the caller is in a module that
1682 * does not have native access enabled.
1683 *
1684 * @spec jni/index.html Java Native Interface Specification
1685 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1686 */
1687 @CallerSensitive
1688 @Restricted
1689 public static void loadLibrary(String libname) {
1690 Class<?> caller = Reflection.getCallerClass();
1691 Reflection.ensureNativeAccess(caller, System.class, "loadLibrary", false);
1692 Runtime.getRuntime().loadLibrary0(caller, libname);
1693 }
1694
1695 /**
1696 * Maps a library name into a platform-specific string representing
1697 * a native library.
1698 *
1699 * @param libname the name of the library.
1700 * @return a platform-dependent native library name.
1701 * @throws NullPointerException if {@code libname} is {@code null}
1702 * @see java.lang.System#loadLibrary(java.lang.String)
1703 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1704 * @since 1.2
1705 */
1706 public static native String mapLibraryName(String libname);
1707
1708 /**
1709 * Create PrintStream for stdout/err based on encoding.
1710 */
1711 private static PrintStream newPrintStream(OutputStream out, String enc) {
1712 if (enc != null) {
1713 return new PrintStream(new BufferedOutputStream(out, 128), true,
1714 Charset.forName(enc, UTF_8.INSTANCE));
1715 }
1716 return new PrintStream(new BufferedOutputStream(out, 128), true);
1717 }
1718
1719 /**
1720 * Logs an exception/error at initialization time to stdout or stderr.
1721 *
1722 * @param printToStderr to print to stderr rather than stdout
1723 * @param printStackTrace to print the stack trace
1724 * @param msg the message to print before the exception, can be {@code null}
1725 * @param e the exception or error
1726 */
1727 private static void logInitException(boolean printToStderr,
1728 boolean printStackTrace,
1729 String msg,
1730 Throwable e) {
1731 if (VM.initLevel() < 1) {
1732 throw new InternalError("system classes not initialized");
1733 }
1734 PrintStream log = (printToStderr) ? err : out;
1735 if (msg != null) {
1736 log.println(msg);
1737 }
1738 if (printStackTrace) {
1739 e.printStackTrace(log);
1740 } else {
1741 log.println(e);
1742 for (Throwable suppressed : e.getSuppressed()) {
1743 log.println("Suppressed: " + suppressed);
1744 }
1745 Throwable cause = e.getCause();
1746 if (cause != null) {
1747 log.println("Caused by: " + cause);
1748 }
1749 }
1750 }
1751
1752 /**
1753 * Create the Properties object from a map - masking out system properties
1754 * that are not intended for public access.
1755 */
1756 private static Properties createProperties(Map<String, String> initialProps) {
1757 Properties properties = new Properties(initialProps.size());
1758 for (var entry : initialProps.entrySet()) {
1759 String prop = entry.getKey();
1760 switch (prop) {
1761 // Do not add private system properties to the Properties
1762 case "sun.nio.MaxDirectMemorySize":
1763 case "sun.nio.PageAlignDirectMemory":
1764 // used by java.lang.Integer.IntegerCache
1765 case "java.lang.Integer.IntegerCache.high":
1766 // used by sun.launcher.LauncherHelper
1767 case "sun.java.launcher.diag":
1768 // used by jdk.internal.loader.ClassLoaders
1769 case "jdk.boot.class.path.append":
1770 break;
1771 default:
1772 properties.put(prop, entry.getValue());
1773 }
1774 }
1775 return properties;
1776 }
1777
1778 /**
1779 * Initialize the system class. Called after thread initialization.
1780 */
1781 private static void initPhase1() {
1782
1783 // register the shared secrets - do this first, since SystemProps.initProperties
1784 // might initialize CharsetDecoders that rely on it
1785 setJavaLangAccess();
1786
1787 // VM might invoke JNU_NewStringPlatform() to set those encoding
1788 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1789 // during "props" initialization.
1790 // The charset is initialized in System.c and does not depend on the Properties.
1791 Map<String, String> tempProps = SystemProps.initProperties();
1792 VersionProps.init(tempProps);
1793
1794 // There are certain system configurations that may be controlled by
1795 // VM options such as the maximum amount of direct memory and
1796 // Integer cache size used to support the object identity semantics
1797 // of autoboxing. Typically, the library will obtain these values
1798 // from the properties set by the VM. If the properties are for
1799 // internal implementation use only, these properties should be
1800 // masked from the system properties.
1801 //
1802 // Save a private copy of the system properties object that
1803 // can only be accessed by the internal implementation.
1804 VM.saveProperties(tempProps);
1805 props = createProperties(tempProps);
1806
1807 // Check if sun.jnu.encoding is supported. If not, replace it with UTF-8.
1808 var jnuEncoding = props.getProperty("sun.jnu.encoding");
1809 if (jnuEncoding == null || !Charset.isSupported(jnuEncoding)) {
1810 notSupportedJnuEncoding = jnuEncoding == null ? "null" : jnuEncoding;
1811 props.setProperty("sun.jnu.encoding", "UTF-8");
1812 }
1813
1814 StaticProperty.javaHome(); // Load StaticProperty to cache the property values
1815
1816 lineSeparator = props.getProperty("line.separator");
1817
1818 FileInputStream fdIn = new In(FileDescriptor.in);
1819 FileOutputStream fdOut = new Out(FileDescriptor.out);
1820 FileOutputStream fdErr = new Out(FileDescriptor.err);
1821 initialIn = new BufferedInputStream(fdIn);
1822 setIn0(initialIn);
1823 // stdout/err.encoding are set when the VM is associated with the terminal,
1824 // thus they are equivalent to Console.charset(), otherwise the encodings
1825 // of those properties default to native.encoding
1826 setOut0(newPrintStream(fdOut, props.getProperty("stdout.encoding")));
1827 initialErr = newPrintStream(fdErr, props.getProperty("stderr.encoding"));
1828 setErr0(initialErr);
1829
1830 // Setup Java signal handlers for HUP, TERM, and INT (where available).
1831 Terminator.setup();
1832
1833 // Initialize any miscellaneous operating system settings that need to be
1834 // set for the class libraries. Currently this is no-op everywhere except
1835 // for Windows where the process-wide error mode is set before the java.io
1836 // classes are used.
1837 VM.initializeOSEnvironment();
1838
1839 // start Finalizer and Reference Handler threads
1840 SharedSecrets.getJavaLangRefAccess().startThreads();
1841
1842 // system properties, java.lang and other core classes are now initialized
1843 VM.initLevel(1);
1844 }
1845
1846 /**
1847 * System.in.
1848 */
1849 private static class In extends FileInputStream {
1850 In(FileDescriptor fd) {
1851 super(fd);
1852 }
1853
1854 @Override
1855 public int read() throws IOException {
1856 boolean attempted = Blocker.begin();
1857 try {
1858 return super.read();
1859 } finally {
1860 Blocker.end(attempted);
1861 }
1862 }
1863
1864 @Override
1865 public int read(byte[] b) throws IOException {
1866 boolean attempted = Blocker.begin();
1867 try {
1868 return super.read(b);
1869 } finally {
1870 Blocker.end(attempted);
1871 }
1872 }
1873
1874 @Override
1875 public int read(byte[] b, int off, int len) throws IOException {
1876 boolean attempted = Blocker.begin();
1877 try {
1878 return super.read(b, off, len);
1879 } finally {
1880 Blocker.end(attempted);
1881 }
1882 }
1883 }
1884
1885 /**
1886 * System.out/System.err wrap this output stream.
1887 */
1888 private static class Out extends FileOutputStream {
1889 Out(FileDescriptor fd) {
1890 super(fd);
1891 }
1892
1893 @Override
1894 public void write(int b) throws IOException {
1895 boolean attempted = Blocker.begin();
1896 try {
1897 super.write(b);
1898 } finally {
1899 Blocker.end(attempted);
1900 }
1901 }
1902
1903 @Override
1904 public void write(byte[] b) throws IOException {
1905 boolean attempted = Blocker.begin();
1906 try {
1907 super.write(b);
1908 } finally {
1909 Blocker.end(attempted);
1910 }
1911 }
1912
1913 @Override
1914 public void write(byte[] b, int off, int len) throws IOException {
1915 boolean attempted = Blocker.begin();
1916 try {
1917 super.write(b, off, len);
1918 } finally {
1919 Blocker.end(attempted);
1920 }
1921 }
1922 }
1923
1924 // @see #initPhase2()
1925 static ModuleLayer bootLayer;
1926
1927 /*
1928 * Invoked by VM. Phase 2 module system initialization.
1929 * Only classes in java.base can be loaded in this phase.
1930 *
1931 * @param printToStderr print exceptions to stderr rather than stdout
1932 * @param printStackTrace print stack trace when exception occurs
1933 *
1934 * @return JNI_OK for success, JNI_ERR for failure
1935 */
1936 private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
1937
1938 try {
1939 bootLayer = ModuleBootstrap.boot();
1940 } catch (Exception | Error e) {
1941 logInitException(printToStderr, printStackTrace,
1942 "Error occurred during initialization of boot layer", e);
1943 return -1; // JNI_ERR
1944 }
1945
1946 // module system initialized
1947 VM.initLevel(2);
1948
1949 return 0; // JNI_OK
1950 }
1951
1952 /*
1953 * Invoked by VM. Phase 3 is the final system initialization:
1954 * 1. set system class loader
1955 * 2. set TCCL
1956 *
1957 * This method must be called after the module system initialization.
1958 */
1959 private static void initPhase3() {
1960
1961 // Emit a warning if java.io.tmpdir is set via the command line
1962 // to a directory that doesn't exist
1963 if (SystemProps.isBadIoTmpdir()) {
1964 System.err.println("WARNING: java.io.tmpdir directory does not exist");
1965 }
1966
1967 String smProp = System.getProperty("java.security.manager");
1968 if (smProp != null) {
1969 switch (smProp) {
1970 case "disallow":
1971 break;
1972 case "allow":
1973 case "":
1974 case "default":
1975 default:
1976 throw new Error("A command line option has attempted to allow or enable the Security Manager."
1977 + " Enabling a Security Manager is not supported.");
1978 }
1979 }
1980
1981 // Emit a warning if `sun.jnu.encoding` is not supported.
1982 if (notSupportedJnuEncoding != null) {
1983 System.err.println(
1984 "WARNING: The encoding of the underlying platform's" +
1985 " file system is not supported: " +
1986 notSupportedJnuEncoding);
1987 }
1988
1989 // initializing the system class loader
1990 VM.initLevel(3);
1991
1992 // system class loader initialized
1993 ClassLoader scl = ClassLoader.initSystemClassLoader();
1994
1995 // set TCCL
1996 Thread.currentThread().setContextClassLoader(scl);
1997
1998 // system is fully initialized
1999 VM.initLevel(4);
2000 }
2001
2002 private static void setJavaLangAccess() {
2003 // Allow privileged classes outside of java.lang
2004 SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
2005 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
2006 return klass.getDeclaredPublicMethods(name, parameterTypes);
2007 }
2008 public Method findMethod(Class<?> klass, boolean publicOnly, String name, Class<?>... parameterTypes) {
2009 return klass.findMethod(publicOnly, name, parameterTypes);
2010 }
2011 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
2012 return klass.getConstantPool();
2013 }
2014 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
2015 return klass.casAnnotationType(oldType, newType);
2016 }
2017 public AnnotationType getAnnotationType(Class<?> klass) {
2018 return klass.getAnnotationType();
2019 }
2020 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2021 return klass.getDeclaredAnnotationMap();
2022 }
2023 public byte[] getRawClassAnnotations(Class<?> klass) {
2024 return klass.getRawAnnotations();
2025 }
2026 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2027 return klass.getRawTypeAnnotations();
2028 }
2029 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2030 return Class.getExecutableTypeAnnotationBytes(executable);
2031 }
2032 public <E extends Enum<E>>
2033 E[] getEnumConstantsShared(Class<E> klass) {
2034 return klass.getEnumConstantsShared();
2035 }
2036 public void blockedOn(Interruptible b) {
2037 Thread.currentThread().blockedOn(b);
2038 }
2039 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2040 Shutdown.add(slot, registerShutdownInProgress, hook);
2041 }
2042 @SuppressWarnings("removal")
2043 public void invokeFinalize(Object o) throws Throwable {
2044 o.finalize();
2045 }
2046 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2047 return cl.createOrGetClassLoaderValueMap();
2048 }
2049 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2050 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2051 }
2052 public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd,
2053 boolean initialize, int flags, Object classData) {
2054 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData);
2055 }
2056 public Class<?> findBootstrapClassOrNull(String name) {
2057 return ClassLoader.findBootstrapClassOrNull(name);
2058 }
2059 public Package definePackage(ClassLoader cl, String name, Module module) {
2060 return cl.definePackage(name, module);
2061 }
2062 public Module defineModule(ClassLoader loader,
2063 ModuleDescriptor descriptor,
2064 URI uri) {
2065 return new Module(null, loader, descriptor, uri);
2066 }
2067 public Module defineUnnamedModule(ClassLoader loader) {
2068 return new Module(loader);
2069 }
2070 public void addReads(Module m1, Module m2) {
2071 m1.implAddReads(m2);
2072 }
2073 public void addReadsAllUnnamed(Module m) {
2074 m.implAddReadsAllUnnamed();
2075 }
2076 public void addExports(Module m, String pn) {
2077 m.implAddExports(pn);
2078 }
2079 public void addExports(Module m, String pn, Module other) {
2080 m.implAddExports(pn, other);
2081 }
2082 public void addExportsToAllUnnamed(Module m, String pn) {
2083 m.implAddExportsToAllUnnamed(pn);
2084 }
2085 public void addOpens(Module m, String pn, Module other) {
2086 m.implAddOpens(pn, other);
2087 }
2088 public void addOpensToAllUnnamed(Module m, String pn) {
2089 m.implAddOpensToAllUnnamed(pn);
2090 }
2091 public void addUses(Module m, Class<?> service) {
2092 m.implAddUses(service);
2093 }
2094 public boolean isReflectivelyExported(Module m, String pn, Module other) {
2095 return m.isReflectivelyExported(pn, other);
2096 }
2097 public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2098 return m.isReflectivelyOpened(pn, other);
2099 }
2100 public Module addEnableNativeAccess(Module m) {
2101 return m.implAddEnableNativeAccess();
2102 }
2103 public boolean addEnableNativeAccess(ModuleLayer layer, String name) {
2104 return layer.addEnableNativeAccess(name);
2105 }
2106 public void addEnableNativeAccessToAllUnnamed() {
2107 Module.implAddEnableNativeAccessToAllUnnamed();
2108 }
2109 public void ensureNativeAccess(Module m, Class<?> owner, String methodName, Class<?> currentClass, boolean jni) {
2110 m.ensureNativeAccess(owner, methodName, currentClass, jni);
2111 }
2112 public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2113 return layer.getServicesCatalog();
2114 }
2115 public void bindToLoader(ModuleLayer layer, ClassLoader loader) {
2116 layer.bindToLoader(loader);
2117 }
2118 public Stream<ModuleLayer> layers(ModuleLayer layer) {
2119 return layer.layers();
2120 }
2121 public Stream<ModuleLayer> layers(ClassLoader loader) {
2122 return ModuleLayer.layers(loader);
2123 }
2124
2125 public int countPositives(byte[] bytes, int offset, int length) {
2126 return StringCoding.countPositives(bytes, offset, length);
2127 }
2128 public int countNonZeroAscii(String s) {
2129 return StringCoding.countNonZeroAscii(s);
2130 }
2131 public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
2132 return String.newStringNoRepl(bytes, cs);
2133 }
2134 public char getUTF16Char(byte[] bytes, int index) {
2135 return StringUTF16.getChar(bytes, index);
2136 }
2137 public void putCharUTF16(byte[] bytes, int index, int ch) {
2138 StringUTF16.putChar(bytes, index, ch);
2139 }
2140 public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2141 return String.getBytesNoRepl(s, cs);
2142 }
2143
2144 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2145 return String.newStringUTF8NoRepl(bytes, off, len, true);
2146 }
2147
2148 public byte[] getBytesUTF8NoRepl(String s) {
2149 return String.getBytesUTF8NoRepl(s);
2150 }
2151
2152 public void inflateBytesToChars(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2153 StringLatin1.inflate(src, srcOff, dst, dstOff, len);
2154 }
2155
2156 public int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len) {
2157 return String.decodeASCII(src, srcOff, dst, dstOff, len);
2158 }
2159
2160 public int encodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len) {
2161 return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
2162 }
2163
2164 public InputStream initialSystemIn() {
2165 return initialIn;
2166 }
2167
2168 public PrintStream initialSystemErr() {
2169 return initialErr;
2170 }
2171
2172 public void setCause(Throwable t, Throwable cause) {
2173 t.setCause(cause);
2174 }
2175
2176 public ProtectionDomain protectionDomain(Class<?> c) {
2177 return c.getProtectionDomain();
2178 }
2179
2180 public MethodHandle stringConcatHelper(String name, MethodType methodType) {
2181 return StringConcatHelper.lookupStatic(name, methodType);
2182 }
2183
2184 public long stringConcatInitialCoder() {
2185 return StringConcatHelper.initialCoder();
2186 }
2187
2188 public long stringConcatMix(long lengthCoder, String constant) {
2189 return StringConcatHelper.mix(lengthCoder, constant);
2190 }
2191
2192 public long stringConcatMix(long lengthCoder, char value) {
2193 return StringConcatHelper.mix(lengthCoder, value);
2194 }
2195
2196 public Object stringConcat1(String[] constants) {
2197 return new StringConcatHelper.Concat1(constants);
2198 }
2199
2200 public byte stringInitCoder() {
2201 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
2202 }
2203
2204 public byte stringCoder(String str) {
2205 return str.coder();
2206 }
2207
2208 public String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
2209 return String.join(prefix, suffix, delimiter, elements, size);
2210 }
2211
2212 public String concat(String prefix, Object value, String suffix) {
2213 return StringConcatHelper.concat(prefix, value, suffix);
2214 }
2215
2216 public Object classData(Class<?> c) {
2217 return c.getClassData();
2218 }
2219
2220 @Override
2221 public NativeLibraries nativeLibrariesFor(ClassLoader loader) {
2222 return ClassLoader.nativeLibrariesFor(loader);
2223 }
2224
2225 public Thread[] getAllThreads() {
2226 return Thread.getAllThreads();
2227 }
2228
2229 public ThreadContainer threadContainer(Thread thread) {
2230 return thread.threadContainer();
2231 }
2232
2233 public void start(Thread thread, ThreadContainer container) {
2234 thread.start(container);
2235 }
2236
2237 public StackableScope headStackableScope(Thread thread) {
2238 return thread.headStackableScopes();
2239 }
2240
2241 public void setHeadStackableScope(StackableScope scope) {
2242 Thread.setHeadStackableScope(scope);
2243 }
2244
2245 public Thread currentCarrierThread() {
2246 return Thread.currentCarrierThread();
2247 }
2248
2249 public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
2250 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
2251 }
2252
2253 public <T> void setCarrierThreadLocal(CarrierThreadLocal<T> local, T value) {
2254 ((ThreadLocal<T>)local).setCarrierThreadLocal(value);
2255 }
2256
2257 public void removeCarrierThreadLocal(CarrierThreadLocal<?> local) {
2258 ((ThreadLocal<?>)local).removeCarrierThreadLocal();
2259 }
2260
2261 public boolean isCarrierThreadLocalPresent(CarrierThreadLocal<?> local) {
2262 return ((ThreadLocal<?>)local).isCarrierThreadLocalPresent();
2263 }
2264
2265 public Object[] scopedValueCache() {
2266 return Thread.scopedValueCache();
2267 }
2268
2269 public void setScopedValueCache(Object[] cache) {
2270 Thread.setScopedValueCache(cache);
2271 }
2272
2273 public Object scopedValueBindings() {
2274 return Thread.scopedValueBindings();
2275 }
2276
2277 public Continuation getContinuation(Thread thread) {
2278 return thread.getContinuation();
2279 }
2280
2281 public void setContinuation(Thread thread, Continuation continuation) {
2282 thread.setContinuation(continuation);
2283 }
2284
2285 public ContinuationScope virtualThreadContinuationScope() {
2286 return VirtualThread.continuationScope();
2287 }
2288
2289 public void parkVirtualThread() {
2290 Thread thread = Thread.currentThread();
2291 if (thread instanceof BaseVirtualThread vthread) {
2292 vthread.park();
2293 } else {
2294 throw new WrongThreadException();
2295 }
2296 }
2297
2298 public void parkVirtualThread(long nanos) {
2299 Thread thread = Thread.currentThread();
2300 if (thread instanceof BaseVirtualThread vthread) {
2301 vthread.parkNanos(nanos);
2302 } else {
2303 throw new WrongThreadException();
2304 }
2305 }
2306
2307 public void unparkVirtualThread(Thread thread) {
2308 if (thread instanceof BaseVirtualThread vthread) {
2309 vthread.unpark();
2310 } else {
2311 throw new WrongThreadException();
2312 }
2313 }
2314
2315 public Executor virtualThreadDefaultScheduler() {
2316 return VirtualThread.defaultScheduler();
2317 }
2318
2319 public StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
2320 ContinuationScope contScope,
2321 Continuation continuation) {
2322 return StackWalker.newInstance(options, null, contScope, continuation);
2323 }
2324
2325 public int classFileFormatVersion(Class<?> clazz) {
2326 return clazz.getClassFileVersion();
2327 }
2328
2329 public String getLoaderNameID(ClassLoader loader) {
2330 return loader != null ? loader.nameAndId() : "null";
2331 }
2332
2333 @Override
2334 public void copyToSegmentRaw(String string, MemorySegment segment, long offset) {
2335 string.copyToSegmentRaw(segment, offset);
2336 }
2337
2338 @Override
2339 public boolean bytesCompatible(String string, Charset charset) {
2340 return string.bytesCompatible(charset);
2341 }
2342 });
2343 }
2344 }