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