1 /*
2 * Copyright (c) 1996, 2021, 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
26 package java.lang.reflect;
27
28 import jdk.internal.access.SharedSecrets;
29 import jdk.internal.misc.VM;
30 import jdk.internal.reflect.CallerSensitive;
31 import jdk.internal.reflect.ConstructorAccessor;
32 import jdk.internal.reflect.Reflection;
33 import jdk.internal.vm.annotation.ForceInline;
34 import jdk.internal.vm.annotation.Stable;
35 import sun.reflect.annotation.TypeAnnotation;
36 import sun.reflect.annotation.TypeAnnotationParser;
37 import sun.reflect.generics.repository.ConstructorRepository;
38 import sun.reflect.generics.factory.CoreReflectionFactory;
39 import sun.reflect.generics.factory.GenericsFactory;
40 import sun.reflect.generics.scope.ConstructorScope;
41 import java.lang.annotation.Annotation;
42 import java.lang.annotation.AnnotationFormatError;
43 import java.util.StringJoiner;
44
45 /**
46 * {@code Constructor} provides information about, and access to, a single
47 * constructor for a class.
48 *
49 * <p>{@code Constructor} permits widening conversions to occur when matching the
50 * actual parameters to newInstance() with the underlying
51 * constructor's formal parameters, but throws an
52 * {@code IllegalArgumentException} if a narrowing conversion would occur.
53 *
54 * @param <T> the class in which the constructor is declared
55 *
56 * @see Member
57 * @see java.lang.Class
58 * @see java.lang.Class#getConstructors()
59 * @see java.lang.Class#getConstructor(Class[])
60 * @see java.lang.Class#getDeclaredConstructors()
61 *
62 * @author Kenneth Russell
63 * @author Nakul Saraiya
64 * @since 1.1
65 */
66 public final class Constructor<T> extends Executable {
67 private final Class<T> clazz;
68 private final int slot;
69 private final Class<?>[] parameterTypes;
70 private final Class<?>[] exceptionTypes;
71 private final int modifiers;
72 // Generics and annotations support
73 private final transient String signature;
74 // generic info repository; lazily initialized
75 private transient ConstructorRepository genericInfo;
76 private final byte[] annotations;
77 private final byte[] parameterAnnotations;
78
79 // Generics infrastructure
80 // Accessor for factory
81 private GenericsFactory getFactory() {
82 // create scope and factory
83 return CoreReflectionFactory.make(this, ConstructorScope.make(this));
84 }
85
86 // Accessor for generic info repository
87 @Override
88 ConstructorRepository getGenericInfo() {
89 // lazily initialize repository if necessary
90 if (genericInfo == null) {
91 // create and cache generic info repository
92 genericInfo =
93 ConstructorRepository.make(getSignature(),
94 getFactory());
95 }
96 return genericInfo; //return cached repository
97 }
98
99 @Stable
100 private ConstructorAccessor constructorAccessor;
101 // For sharing of ConstructorAccessors. This branching structure
102 // is currently only two levels deep (i.e., one root Constructor
103 // and potentially many Constructor objects pointing to it.)
104 //
105 // If this branching structure would ever contain cycles, deadlocks can
106 // occur in annotation code.
107 private Constructor<T> root;
108
109 @Override
110 Constructor<T> getRoot() {
111 return root;
112 }
113
114 /**
115 * Package-private constructor used by ReflectAccess to enable
116 * instantiation of these objects in Java code from the java.lang
117 * package via jdk.internal.access.JavaLangReflectAccess.
118 */
119 Constructor(Class<T> declaringClass,
120 Class<?>[] parameterTypes,
121 Class<?>[] checkedExceptions,
122 int modifiers,
123 int slot,
124 String signature,
125 byte[] annotations,
126 byte[] parameterAnnotations) {
127 this.clazz = declaringClass;
128 this.parameterTypes = parameterTypes;
129 this.exceptionTypes = checkedExceptions;
130 this.modifiers = modifiers;
131 this.slot = slot;
132 this.signature = signature;
133 this.annotations = annotations;
134 this.parameterAnnotations = parameterAnnotations;
135 }
136
137 /**
138 * Package-private routine (exposed to java.lang.Class via
139 * ReflectAccess) which returns a copy of this Constructor. The copy's
140 * "root" field points to this Constructor.
141 */
142 Constructor<T> copy() {
143 // This routine enables sharing of ConstructorAccessor objects
144 // among Constructor objects which refer to the same underlying
145 // method in the VM. (All of this contortion is only necessary
146 // because of the "accessibility" bit in AccessibleObject,
147 // which implicitly requires that new java.lang.reflect
148 // objects be fabricated for each reflective call on Class
149 // objects.)
150 if (this.root != null)
151 throw new IllegalArgumentException("Can not copy a non-root Constructor");
152
153 Constructor<T> res = new Constructor<>(clazz,
154 parameterTypes,
155 exceptionTypes, modifiers, slot,
156 signature,
157 annotations,
158 parameterAnnotations);
159 res.root = this;
160 // Might as well eagerly propagate this if already present
161 res.constructorAccessor = constructorAccessor;
162 return res;
163 }
164
165 /**
166 * {@inheritDoc}
167 *
168 * <p> A {@code SecurityException} is also thrown if this object is a
169 * {@code Constructor} object for the class {@code Class} and {@code flag}
170 * is true. </p>
171 *
172 * @param flag {@inheritDoc}
173 *
174 * @throws InaccessibleObjectException {@inheritDoc}
175 * @throws SecurityException if the request is denied by the security manager
176 * or this is a constructor for {@code java.lang.Class}
177 *
178 */
179 @Override
180 @CallerSensitive
181 public void setAccessible(boolean flag) {
182 AccessibleObject.checkPermission();
183 if (flag) {
184 checkCanSetAccessible(Reflection.getCallerClass());
185 }
186 setAccessible0(flag);
187 }
188
189 @Override
190 void checkCanSetAccessible(Class<?> caller) {
191 checkCanSetAccessible(caller, clazz);
192 if (clazz == Class.class) {
193 // can we change this to InaccessibleObjectException?
194 throw new SecurityException("Cannot make a java.lang.Class"
195 + " constructor accessible");
196 }
197 }
198
199 @Override
200 boolean hasGenericInformation() {
201 return (getSignature() != null);
202 }
203
204 @Override
205 byte[] getAnnotationBytes() {
206 return annotations;
207 }
208
209 /**
210 * Returns the {@code Class} object representing the class that
211 * declares the constructor represented by this object.
212 */
213 @Override
214 public Class<T> getDeclaringClass() {
215 return clazz;
216 }
217
218 /**
219 * Returns the name of this constructor, as a string. This is
220 * the binary name of the constructor's declaring class.
221 */
222 @Override
223 public String getName() {
224 return getDeclaringClass().getName();
225 }
226
227 /**
228 * {@inheritDoc}
229 * @jls 8.8.3 Constructor Modifiers
230 */
231 @Override
232 public int getModifiers() {
233 return modifiers;
234 }
235
236 /**
237 * {@inheritDoc}
238 * @throws GenericSignatureFormatError {@inheritDoc}
239 * @since 1.5
240 */
241 @Override
242 @SuppressWarnings({"rawtypes", "unchecked"})
243 public TypeVariable<Constructor<T>>[] getTypeParameters() {
244 if (getSignature() != null) {
245 return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
246 } else
247 return (TypeVariable<Constructor<T>>[])new TypeVariable[0];
248 }
249
250
251 @Override
252 Class<?>[] getSharedParameterTypes() {
253 return parameterTypes;
254 }
255
256 @Override
257 Class<?>[] getSharedExceptionTypes() {
258 return exceptionTypes;
259 }
260
261 /**
262 * {@inheritDoc}
263 */
264 @Override
265 public Class<?>[] getParameterTypes() {
266 return parameterTypes.clone();
267 }
268
269 /**
270 * {@inheritDoc}
271 * @since 1.8
272 */
273 public int getParameterCount() { return parameterTypes.length; }
274
275 /**
276 * {@inheritDoc}
277 * @throws GenericSignatureFormatError {@inheritDoc}
278 * @throws TypeNotPresentException {@inheritDoc}
279 * @throws MalformedParameterizedTypeException {@inheritDoc}
280 * @since 1.5
281 */
282 @Override
283 public Type[] getGenericParameterTypes() {
284 return super.getGenericParameterTypes();
285 }
286
287 /**
288 * {@inheritDoc}
289 */
290 @Override
291 public Class<?>[] getExceptionTypes() {
292 return exceptionTypes.clone();
293 }
294
295
296 /**
297 * {@inheritDoc}
298 * @throws GenericSignatureFormatError {@inheritDoc}
299 * @throws TypeNotPresentException {@inheritDoc}
300 * @throws MalformedParameterizedTypeException {@inheritDoc}
301 * @since 1.5
302 */
303 @Override
304 public Type[] getGenericExceptionTypes() {
305 return super.getGenericExceptionTypes();
306 }
307
308 /**
309 * Compares this {@code Constructor} against the specified object.
310 * Returns true if the objects are the same. Two {@code Constructor} objects are
311 * the same if they were declared by the same class and have the
312 * same formal parameter types.
313 */
314 public boolean equals(Object obj) {
315 if (obj instanceof Constructor<?> other) {
316 if (getDeclaringClass() == other.getDeclaringClass()) {
317 return equalParamTypes(parameterTypes, other.parameterTypes);
318 }
319 }
320 return false;
321 }
322
323 /**
324 * Returns a hashcode for this {@code Constructor}. The hashcode is
325 * the same as the hashcode for the underlying constructor's
326 * declaring class name.
327 */
328 public int hashCode() {
329 return getDeclaringClass().getName().hashCode();
330 }
331
332 /**
333 * Returns a string describing this {@code Constructor}. The string is
334 * formatted as the constructor access modifiers, if any,
335 * followed by the fully-qualified name of the declaring class,
336 * followed by a parenthesized, comma-separated list of the
337 * constructor's formal parameter types. For example:
338 * <pre>{@code
339 * public java.util.HashMap(int,float)
340 * }</pre>
341 *
342 * <p>If the constructor is declared to throw exceptions, the
343 * parameter list is followed by a space, followed by the word
344 * "{@code throws}" followed by a comma-separated list of the
345 * thrown exception types.
346 *
347 * <p>The only possible modifiers for constructors are the access
348 * modifiers {@code public}, {@code protected} or
349 * {@code private}. Only one of these may appear, or none if the
350 * constructor has default (package) access.
351 *
352 * @return a string describing this {@code Constructor}
353 * @jls 8.8.3 Constructor Modifiers
354 * @jls 8.9.2 Enum Body Declarations
355 */
356 public String toString() {
357 return sharedToString(Modifier.constructorModifiers(),
358 false,
359 parameterTypes,
360 exceptionTypes);
361 }
362
363 @Override
364 void specificToStringHeader(StringBuilder sb) {
365 sb.append(getDeclaringClass().getTypeName());
366 }
367
368 @Override
369 String toShortString() {
370 StringBuilder sb = new StringBuilder("constructor ");
371 sb.append(getDeclaringClass().getTypeName());
372 sb.append('(');
373 StringJoiner sj = new StringJoiner(",");
374 for (Class<?> parameterType : getSharedParameterTypes()) {
375 sj.add(parameterType.getTypeName());
376 }
377 sb.append(sj);
378 sb.append(')');
379 return sb.toString();
380 }
381
382 /**
383 * Returns a string describing this {@code Constructor},
384 * including type parameters. The string is formatted as the
385 * constructor access modifiers, if any, followed by an
386 * angle-bracketed comma separated list of the constructor's type
387 * parameters, if any, including informative bounds of the
388 * type parameters, if any, followed by the fully-qualified name of the
389 * declaring class, followed by a parenthesized, comma-separated
390 * list of the constructor's generic formal parameter types.
391 *
392 * If this constructor was declared to take a variable number of
393 * arguments, instead of denoting the last parameter as
394 * "<code><i>Type</i>[]</code>", it is denoted as
395 * "<code><i>Type</i>...</code>".
396 *
397 * A space is used to separate access modifiers from one another
398 * and from the type parameters or class name. If there are no
399 * type parameters, the type parameter list is elided; if the type
400 * parameter list is present, a space separates the list from the
401 * class name. If the constructor is declared to throw
402 * exceptions, the parameter list is followed by a space, followed
403 * by the word "{@code throws}" followed by a
404 * comma-separated list of the generic thrown exception types.
405 *
406 * <p>The only possible modifiers for constructors are the access
407 * modifiers {@code public}, {@code protected} or
408 * {@code private}. Only one of these may appear, or none if the
409 * constructor has default (package) access.
410 *
411 * @return a string describing this {@code Constructor},
412 * include type parameters
413 *
414 * @since 1.5
415 * @jls 8.8.3 Constructor Modifiers
416 * @jls 8.9.2 Enum Body Declarations
417 */
418 @Override
419 public String toGenericString() {
420 return sharedToGenericString(Modifier.constructorModifiers(), false);
421 }
422
423 @Override
424 void specificToGenericStringHeader(StringBuilder sb) {
425 specificToStringHeader(sb);
426 }
427
428 /**
429 * Uses the constructor represented by this {@code Constructor} object to
430 * create and initialize a new instance of the constructor's
431 * declaring class, with the specified initialization parameters.
432 * Individual parameters are automatically unwrapped to match
433 * primitive formal parameters, and both primitive and reference
434 * parameters are subject to method invocation conversions as necessary.
435 *
436 * <p>If the number of formal parameters required by the underlying constructor
437 * is 0, the supplied {@code initargs} array may be of length 0 or null.
438 *
439 * <p>If the constructor's declaring class is an inner class in a
440 * non-static context, the first argument to the constructor needs
441 * to be the enclosing instance; see section {@jls 15.9.3} of
442 * <cite>The Java Language Specification</cite>.
443 *
444 * <p>If the required access and argument checks succeed and the
445 * instantiation will proceed, the constructor's declaring class
446 * is initialized if it has not already been initialized.
447 *
448 * <p>If the constructor completes normally, returns the newly
449 * created and initialized instance.
450 *
451 * @param initargs array of objects to be passed as arguments to
452 * the constructor call; values of primitive types are wrapped in
453 * a wrapper object of the appropriate type (e.g. a {@code float}
454 * in a {@link java.lang.Float Float})
455 *
456 * @return a new object created by calling the constructor
457 * this object represents
458 *
459 * @throws IllegalAccessException if this {@code Constructor} object
460 * is enforcing Java language access control and the underlying
461 * constructor is inaccessible.
462 * @throws IllegalArgumentException if the number of actual
463 * and formal parameters differ; if an unwrapping
464 * conversion for primitive arguments fails; or if,
465 * after possible unwrapping, a parameter value
466 * cannot be converted to the corresponding formal
467 * parameter type by a method invocation conversion; if
468 * this constructor pertains to an enum class.
469 * @throws InstantiationException if the class that declares the
470 * underlying constructor represents an abstract class.
471 * @throws InvocationTargetException if the underlying constructor
472 * throws an exception.
473 * @throws ExceptionInInitializerError if the initialization provoked
474 * by this method fails.
475 */
476 @CallerSensitive
477 @ForceInline // to ensure Reflection.getCallerClass optimization
478 public T newInstance(Object ... initargs)
479 throws InstantiationException, IllegalAccessException,
480 IllegalArgumentException, InvocationTargetException
481 {
482 Class<?> caller = override ? null : Reflection.getCallerClass();
483 return newInstanceWithCaller(initargs, !override, caller);
484 }
485
486 /* package-private */
487 T newInstanceWithCaller(Object[] args, boolean checkAccess, Class<?> caller)
488 throws InstantiationException, IllegalAccessException,
489 InvocationTargetException
490 {
491 if (checkAccess)
492 checkAccess(caller, clazz, clazz, modifiers);
493
494 ConstructorAccessor ca = constructorAccessor; // read @Stable
495 if (ca == null) {
496 ca = acquireConstructorAccessor();
497 }
498 @SuppressWarnings("unchecked")
499 T inst = (T) ca.newInstance(args);
500 return inst;
501 }
502
503 /**
504 * {@inheritDoc}
505 * @since 1.5
506 * @jls 8.4.1 Formal Parameters
507 */
508 @Override
509 public boolean isVarArgs() {
510 return super.isVarArgs();
511 }
512
513 /**
514 * {@inheritDoc}
515 * @jls 13.1 The Form of a Binary
516 * @jvms 4.6 Methods
517 * @since 1.5
518 * @see <a
519 * href="{@docRoot}/java.base/java/lang/reflect/package-summary.html#LanguageJvmModel">Java
520 * programming language and JVM modeling in core reflection</a>
521 */
522 @Override
523 public boolean isSynthetic() {
524 return super.isSynthetic();
525 }
526
527 // NOTE that there is no synchronization used here. It is correct
528 // (though not efficient) to generate more than one
529 // ConstructorAccessor for a given Constructor. However, avoiding
530 // synchronization will probably make the implementation more
531 // scalable.
532 private ConstructorAccessor acquireConstructorAccessor() {
533
534 // First check to see if one has been created yet, and take it
535 // if so.
536 Constructor<?> root = this.root;
537 ConstructorAccessor tmp = root == null ? null : root.getConstructorAccessor();
538 if (tmp != null) {
539 constructorAccessor = tmp;
540 } else {
541 // Otherwise fabricate one and propagate it up to the root
542 // Ensure the declaring class is not an Enum class.
543 if ((clazz.getModifiers() & Modifier.ENUM) != 0)
544 throw new IllegalArgumentException("Cannot reflectively create enum objects");
545
546 tmp = reflectionFactory.newConstructorAccessor(this);
547 // set the constructor accessor only if it's not using native implementation
548 if (VM.isJavaLangInvokeInited())
549 setConstructorAccessor(tmp);
550 }
551
552 return tmp;
553 }
554
555 // Returns ConstructorAccessor for this Constructor object, not
556 // looking up the chain to the root
557 ConstructorAccessor getConstructorAccessor() {
558 return constructorAccessor;
559 }
560
561 // Sets the ConstructorAccessor for this Constructor object and
562 // (recursively) its root
563 void setConstructorAccessor(ConstructorAccessor accessor) {
564 constructorAccessor = accessor;
565 // Propagate up
566 Constructor<?> root = this.root;
567 if (root != null) {
568 root.setConstructorAccessor(accessor);
569 }
570 }
571
572 int getSlot() {
573 return slot;
574 }
575
576 String getSignature() {
577 return signature;
578 }
579
580 byte[] getRawAnnotations() {
581 return annotations;
582 }
583
584 byte[] getRawParameterAnnotations() {
585 return parameterAnnotations;
586 }
587
588
589 /**
590 * {@inheritDoc}
591 *
592 * @throws NullPointerException {@inheritDoc}
593 * @since 1.5
594 */
595 @Override
596 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
597 return super.getAnnotation(annotationClass);
598 }
599
600 /**
601 * {@inheritDoc}
602 * @since 1.5
603 */
604 @Override
605 public Annotation[] getDeclaredAnnotations() {
606 return super.getDeclaredAnnotations();
607 }
608
609 /**
610 * {@inheritDoc}
611 * @since 1.5
612 */
613 @Override
614 public Annotation[][] getParameterAnnotations() {
615 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
616 }
617
618 @Override
619 boolean handleParameterNumberMismatch(int resultLength, Class<?>[] parameterTypes) {
620 int numParameters = parameterTypes.length;
621 Class<?> declaringClass = getDeclaringClass();
622 if (declaringClass.isEnum()) {
623 return resultLength + 2 == numParameters &&
624 parameterTypes[0] == String.class &&
625 parameterTypes[1] == int.class;
626 } else if (
627 declaringClass.isAnonymousClass() ||
628 declaringClass.isLocalClass() )
629 return false; // Can't do reliable parameter counting
630 else {
631 if (declaringClass.isMemberClass() &&
632 ((declaringClass.getModifiers() & Modifier.STATIC) == 0) &&
633 resultLength + 1 == numParameters) {
634 return true;
635 } else {
636 throw new AnnotationFormatError(
637 "Parameter annotations don't match number of parameters");
638 }
639 }
640 }
641
642 /**
643 * {@inheritDoc}
644 * @since 1.8
645 */
646 @Override
647 public AnnotatedType getAnnotatedReturnType() {
648 return getAnnotatedReturnType0(getDeclaringClass());
649 }
650
651 /**
652 * {@inheritDoc}
653 * @since 1.8
654 */
655 @Override
656 public AnnotatedType getAnnotatedReceiverType() {
657 Class<?> thisDeclClass = getDeclaringClass();
658 Class<?> enclosingClass = thisDeclClass.getEnclosingClass();
659
660 if (enclosingClass == null) {
661 // A Constructor for a top-level class
662 return null;
663 }
664
665 Class<?> outerDeclaringClass = thisDeclClass.getDeclaringClass();
666 if (outerDeclaringClass == null) {
667 // A constructor for a local or anonymous class
668 return null;
669 }
670
671 // Either static nested or inner class
672 if (Modifier.isStatic(thisDeclClass.getModifiers())) {
673 // static nested
674 return null;
675 }
676
677 // A Constructor for an inner class
678 return TypeAnnotationParser.buildAnnotatedType(getTypeAnnotationBytes0(),
679 SharedSecrets.getJavaLangAccess().
680 getConstantPool(thisDeclClass),
681 this,
682 thisDeclClass,
683 parameterize(enclosingClass),
684 TypeAnnotation.TypeAnnotationTarget.METHOD_RECEIVER);
685 }
686 }