1 /*
2 * Copyright (c) 1996, 2013, 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.HotSpotIntrinsicCandidate;
29 import jdk.internal.misc.SharedSecrets;
30 import jdk.internal.reflect.CallerSensitive;
31 import jdk.internal.reflect.MethodAccessor;
32 import jdk.internal.reflect.Reflection;
33 import sun.reflect.generics.repository.MethodRepository;
34 import sun.reflect.generics.factory.CoreReflectionFactory;
35 import sun.reflect.generics.factory.GenericsFactory;
36 import sun.reflect.generics.scope.MethodScope;
37 import sun.reflect.annotation.AnnotationType;
38 import sun.reflect.annotation.AnnotationParser;
39 import java.lang.annotation.Annotation;
40 import java.lang.annotation.AnnotationFormatError;
41 import java.nio.ByteBuffer;
42
43 /**
44 * A {@code Method} provides information about, and access to, a single method
45 * on a class or interface. The reflected method may be a class method
46 * or an instance method (including an abstract method).
47 *
48 * <p>A {@code Method} permits widening conversions to occur when matching the
49 * actual parameters to invoke with the underlying method's formal
50 * parameters, but it throws an {@code IllegalArgumentException} if a
51 * narrowing conversion would occur.
52 *
53 * @see Member
54 * @see java.lang.Class
55 * @see java.lang.Class#getMethods()
56 * @see java.lang.Class#getMethod(String, Class[])
57 * @see java.lang.Class#getDeclaredMethods()
58 * @see java.lang.Class#getDeclaredMethod(String, Class[])
59 *
60 * @author Kenneth Russell
61 * @author Nakul Saraiya
62 */
63 public final class Method extends Executable {
64 private Class<?> clazz;
65 private int slot;
66 // This is guaranteed to be interned by the VM in the 1.4
67 // reflection implementation
68 private String name;
69 private Class<?> returnType;
70 private Class<?>[] parameterTypes;
71 private Class<?>[] exceptionTypes;
72 private int modifiers;
73 // Generics and annotations support
74 private transient String signature;
75 // generic info repository; lazily initialized
76 private transient MethodRepository genericInfo;
77 private byte[] annotations;
78 private byte[] parameterAnnotations;
79 private byte[] annotationDefault;
80 private volatile MethodAccessor methodAccessor;
81 // For sharing of MethodAccessors. This branching structure is
82 // currently only two levels deep (i.e., one root Method and
83 // potentially many Method objects pointing to it.)
84 //
85 // If this branching structure would ever contain cycles, deadlocks can
86 // occur in annotation code.
87 private Method root;
88
89 // Generics infrastructure
90 private String getGenericSignature() {return signature;}
91
92 // Accessor for factory
93 private GenericsFactory getFactory() {
94 // create scope and factory
95 return CoreReflectionFactory.make(this, MethodScope.make(this));
96 }
97
98 // Accessor for generic info repository
99 @Override
100 MethodRepository getGenericInfo() {
101 // lazily initialize repository if necessary
102 if (genericInfo == null) {
103 // create and cache generic info repository
104 genericInfo = MethodRepository.make(getGenericSignature(),
105 getFactory());
106 }
107 return genericInfo; //return cached repository
108 }
109
110 /**
111 * Package-private constructor used by ReflectAccess to enable
112 * instantiation of these objects in Java code from the java.lang
113 * package via sun.reflect.LangReflectAccess.
114 */
115 Method(Class<?> declaringClass,
116 String name,
117 Class<?>[] parameterTypes,
118 Class<?> returnType,
119 Class<?>[] checkedExceptions,
120 int modifiers,
121 int slot,
122 String signature,
123 byte[] annotations,
124 byte[] parameterAnnotations,
125 byte[] annotationDefault) {
126 this.clazz = declaringClass;
127 this.name = name;
128 this.parameterTypes = parameterTypes;
129 this.returnType = returnType;
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 this.annotationDefault = annotationDefault;
137 }
138
139 /**
140 * Package-private routine (exposed to java.lang.Class via
141 * ReflectAccess) which returns a copy of this Method. The copy's
142 * "root" field points to this Method.
143 */
144 Method copy() {
145 // This routine enables sharing of MethodAccessor objects
146 // among Method objects which refer to the same underlying
147 // method in the VM. (All of this contortion is only necessary
148 // because of the "accessibility" bit in AccessibleObject,
149 // which implicitly requires that new java.lang.reflect
150 // objects be fabricated for each reflective call on Class
151 // objects.)
152 if (this.root != null)
153 throw new IllegalArgumentException("Can not copy a non-root Method");
154
155 Method res = new Method(clazz, name, parameterTypes, returnType,
156 exceptionTypes, modifiers, slot, signature,
157 annotations, parameterAnnotations, annotationDefault);
158 res.root = this;
159 // Might as well eagerly propagate this if already present
160 res.methodAccessor = methodAccessor;
161 return res;
162 }
163
164 /**
165 * Make a copy of a leaf method.
166 */
167 Method leafCopy() {
168 if (this.root == null)
169 throw new IllegalArgumentException("Can only leafCopy a non-root Method");
170
171 Method res = new Method(clazz, name, parameterTypes, returnType,
172 exceptionTypes, modifiers, slot, signature,
173 annotations, parameterAnnotations, annotationDefault);
174 res.root = root;
175 res.methodAccessor = methodAccessor;
176 return res;
177 }
178
179 @Override
180 @CallerSensitive
181 public void setAccessible(boolean flag) {
182 AccessibleObject.checkPermission();
183 if (flag) checkCanSetAccessible(Reflection.getCallerClass());
184 setAccessible0(flag);
185 }
186
187 @Override
188 void checkCanSetAccessible(Class<?> caller) {
189 checkCanSetAccessible(caller, clazz);
190 }
191
192 /**
193 * Used by Excecutable for annotation sharing.
194 */
195 @Override
196 Executable getRoot() {
197 return root;
198 }
199
200 @Override
201 boolean hasGenericInformation() {
202 return (getGenericSignature() != null);
203 }
204
205 @Override
206 byte[] getAnnotationBytes() {
207 return annotations;
208 }
209
210 /**
211 * {@inheritDoc}
212 */
213 @Override
214 public Class<?> getDeclaringClass() {
215 return clazz;
216 }
217
218 /**
219 * Returns the name of the method represented by this {@code Method}
220 * object, as a {@code String}.
221 */
222 @Override
223 public String getName() {
224 return name;
225 }
226
227 /**
228 * {@inheritDoc}
229 */
230 @Override
231 public int getModifiers() {
232 return modifiers;
233 }
234
235 /**
236 * {@inheritDoc}
237 * @throws GenericSignatureFormatError {@inheritDoc}
238 * @since 1.5
239 */
240 @Override
241 @SuppressWarnings({"rawtypes", "unchecked"})
242 public TypeVariable<Method>[] getTypeParameters() {
243 if (getGenericSignature() != null)
244 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
245 else
246 return (TypeVariable<Method>[])new TypeVariable[0];
247 }
248
249 /**
250 * Returns a {@code Class} object that represents the formal return type
251 * of the method represented by this {@code Method} object.
252 *
253 * @return the return type for the method this object represents
254 */
255 public Class<?> getReturnType() {
256 return returnType;
257 }
258
259 /**
260 * Returns a {@code Type} object that represents the formal return
261 * type of the method represented by this {@code Method} object.
262 *
263 * <p>If the return type is a parameterized type,
264 * the {@code Type} object returned must accurately reflect
265 * the actual type parameters used in the source code.
266 *
267 * <p>If the return type is a type variable or a parameterized type, it
268 * is created. Otherwise, it is resolved.
269 *
270 * @return a {@code Type} object that represents the formal return
271 * type of the underlying method
272 * @throws GenericSignatureFormatError
273 * if the generic method signature does not conform to the format
274 * specified in
275 * <cite>The Java™ Virtual Machine Specification</cite>
276 * @throws TypeNotPresentException if the underlying method's
277 * return type refers to a non-existent type declaration
278 * @throws MalformedParameterizedTypeException if the
279 * underlying method's return typed refers to a parameterized
280 * type that cannot be instantiated for any reason
281 * @since 1.5
282 */
283 public Type getGenericReturnType() {
284 if (getGenericSignature() != null) {
285 return getGenericInfo().getReturnType();
286 } else { return getReturnType();}
287 }
288
289 /**
290 * {@inheritDoc}
291 */
292 @Override
293 public Class<?>[] getParameterTypes() {
294 return parameterTypes.clone();
295 }
296
297 /**
298 * {@inheritDoc}
299 * @since 1.8
300 */
301 public int getParameterCount() { return parameterTypes.length; }
302
303
304 /**
305 * {@inheritDoc}
306 * @throws GenericSignatureFormatError {@inheritDoc}
307 * @throws TypeNotPresentException {@inheritDoc}
308 * @throws MalformedParameterizedTypeException {@inheritDoc}
309 * @since 1.5
310 */
311 @Override
312 public Type[] getGenericParameterTypes() {
313 return super.getGenericParameterTypes();
314 }
315
316 /**
317 * {@inheritDoc}
318 */
319 @Override
320 public Class<?>[] getExceptionTypes() {
321 return exceptionTypes.clone();
322 }
323
324 /**
325 * {@inheritDoc}
326 * @throws GenericSignatureFormatError {@inheritDoc}
327 * @throws TypeNotPresentException {@inheritDoc}
328 * @throws MalformedParameterizedTypeException {@inheritDoc}
329 * @since 1.5
330 */
331 @Override
332 public Type[] getGenericExceptionTypes() {
333 return super.getGenericExceptionTypes();
334 }
335
336 /**
337 * Compares this {@code Method} against the specified object. Returns
338 * true if the objects are the same. Two {@code Methods} are the same if
339 * they were declared by the same class and have the same name
340 * and formal parameter types and return type.
341 */
342 public boolean equals(Object obj) {
343 if (obj != null && obj instanceof Method) {
344 Method other = (Method)obj;
345 if ((getDeclaringClass() == other.getDeclaringClass())
346 && (getName() == other.getName())) {
347 if (!returnType.equals(other.getReturnType()))
348 return false;
349 return equalParamTypes(parameterTypes, other.parameterTypes);
350 }
351 }
352 return false;
353 }
354
355 /**
356 * Returns a hashcode for this {@code Method}. The hashcode is computed
357 * as the exclusive-or of the hashcodes for the underlying
358 * method's declaring class name and the method's name.
359 */
360 public int hashCode() {
361 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
362 }
363
364 /**
365 * Returns a string describing this {@code Method}. The string is
366 * formatted as the method access modifiers, if any, followed by
367 * the method return type, followed by a space, followed by the
368 * class declaring the method, followed by a period, followed by
369 * the method name, followed by a parenthesized, comma-separated
370 * list of the method's formal parameter types. If the method
371 * throws checked exceptions, the parameter list is followed by a
372 * space, followed by the word throws followed by a
373 * comma-separated list of the thrown exception types.
374 * For example:
375 * <pre>
376 * public boolean java.lang.Object.equals(java.lang.Object)
377 * </pre>
378 *
379 * <p>The access modifiers are placed in canonical order as
380 * specified by "The Java Language Specification". This is
381 * {@code public}, {@code protected} or {@code private} first,
382 * and then other modifiers in the following order:
383 * {@code abstract}, {@code default}, {@code static}, {@code final},
384 * {@code synchronized}, {@code native}, {@code strictfp}.
385 *
386 * @return a string describing this {@code Method}
387 *
388 * @jls 8.4.3 Method Modifiers
389 * @jls 9.4 Method Declarations
390 * @jls 9.6.1 Annotation Type Elements
391 */
392 public String toString() {
393 return sharedToString(Modifier.methodModifiers(),
394 isDefault(),
395 parameterTypes,
396 exceptionTypes);
397 }
398
399 @Override
400 void specificToStringHeader(StringBuilder sb) {
401 sb.append(getReturnType().getTypeName()).append(' ');
402 sb.append(getDeclaringClass().getTypeName()).append('.');
403 sb.append(getName());
404 }
405
406 /**
407 * Returns a string describing this {@code Method}, including
408 * type parameters. The string is formatted as the method access
409 * modifiers, if any, followed by an angle-bracketed
410 * comma-separated list of the method's type parameters, if any,
411 * followed by the method's generic return type, followed by a
412 * space, followed by the class declaring the method, followed by
413 * a period, followed by the method name, followed by a
414 * parenthesized, comma-separated list of the method's generic
415 * formal parameter types.
416 *
417 * If this method was declared to take a variable number of
418 * arguments, instead of denoting the last parameter as
419 * "<code><i>Type</i>[]</code>", it is denoted as
420 * "<code><i>Type</i>...</code>".
421 *
422 * A space is used to separate access modifiers from one another
423 * and from the type parameters or return type. If there are no
424 * type parameters, the type parameter list is elided; if the type
425 * parameter list is present, a space separates the list from the
426 * class name. If the method is declared to throw exceptions, the
427 * parameter list is followed by a space, followed by the word
428 * throws followed by a comma-separated list of the generic thrown
429 * exception types.
430 *
431 * <p>The access modifiers are placed in canonical order as
432 * specified by "The Java Language Specification". This is
433 * {@code public}, {@code protected} or {@code private} first,
434 * and then other modifiers in the following order:
435 * {@code abstract}, {@code default}, {@code static}, {@code final},
436 * {@code synchronized}, {@code native}, {@code strictfp}.
437 *
438 * @return a string describing this {@code Method},
439 * include type parameters
440 *
441 * @since 1.5
442 *
443 * @jls 8.4.3 Method Modifiers
444 * @jls 9.4 Method Declarations
445 * @jls 9.6.1 Annotation Type Elements
446 */
447 @Override
448 public String toGenericString() {
449 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
450 }
451
452 @Override
453 void specificToGenericStringHeader(StringBuilder sb) {
454 Type genRetType = getGenericReturnType();
455 sb.append(genRetType.getTypeName()).append(' ');
456 sb.append(getDeclaringClass().getTypeName()).append('.');
457 sb.append(getName());
458 }
459
460 /**
461 * Invokes the underlying method represented by this {@code Method}
462 * object, on the specified object with the specified parameters.
463 * Individual parameters are automatically unwrapped to match
464 * primitive formal parameters, and both primitive and reference
465 * parameters are subject to method invocation conversions as
466 * necessary.
467 *
468 * <p>If the underlying method is static, then the specified {@code obj}
469 * argument is ignored. It may be null.
470 *
471 * <p>If the number of formal parameters required by the underlying method is
472 * 0, the supplied {@code args} array may be of length 0 or null.
473 *
474 * <p>If the underlying method is an instance method, it is invoked
475 * using dynamic method lookup as documented in The Java Language
476 * Specification, Second Edition, section 15.12.4.4; in particular,
477 * overriding based on the runtime type of the target object will occur.
478 *
479 * <p>If the underlying method is static, the class that declared
480 * the method is initialized if it has not already been initialized.
481 *
482 * <p>If the method completes normally, the value it returns is
483 * returned to the caller of invoke; if the value has a primitive
484 * type, it is first appropriately wrapped in an object. However,
485 * if the value has the type of an array of a primitive type, the
486 * elements of the array are <i>not</i> wrapped in objects; in
487 * other words, an array of primitive type is returned. If the
488 * underlying method return type is void, the invocation returns
489 * null.
490 *
491 * @param obj the object the underlying method is invoked from
492 * @param args the arguments used for the method call
493 * @return the result of dispatching the method represented by
494 * this object on {@code obj} with parameters
495 * {@code args}
496 *
497 * @exception IllegalAccessException if this {@code Method} object
498 * is enforcing Java language access control and the underlying
499 * method is inaccessible.
500 * @exception IllegalArgumentException if the method is an
501 * instance method and the specified object argument
502 * is not an instance of the class or interface
503 * declaring the underlying method (or of a subclass
504 * or implementor thereof); if the number of actual
505 * and formal parameters differ; if an unwrapping
506 * conversion for primitive arguments fails; or if,
507 * after possible unwrapping, a parameter value
508 * cannot be converted to the corresponding formal
509 * parameter type by a method invocation conversion.
510 * @exception InvocationTargetException if the underlying method
511 * throws an exception.
512 * @exception NullPointerException if the specified object is null
513 * and the method is an instance method.
514 * @exception ExceptionInInitializerError if the initialization
515 * provoked by this method fails.
516 */
517 @CallerSensitive
518 @HotSpotIntrinsicCandidate
519 public Object invoke(Object obj, Object... args)
520 throws IllegalAccessException, IllegalArgumentException,
521 InvocationTargetException
522 {
523 if (!override) {
524 Class<?> caller = Reflection.getCallerClass();
525 checkAccess(caller, clazz, obj, modifiers);
526 }
527 MethodAccessor ma = methodAccessor; // read volatile
528 if (ma == null) {
529 ma = acquireMethodAccessor();
530 }
531 return ma.invoke(obj, args);
532 }
533
534 /**
535 * Returns {@code true} if this method is a bridge
536 * method; returns {@code false} otherwise.
537 *
538 * @return true if and only if this method is a bridge
539 * method as defined by the Java Language Specification.
540 * @since 1.5
541 */
542 public boolean isBridge() {
543 return (getModifiers() & Modifier.BRIDGE) != 0;
544 }
545
546 /**
547 * {@inheritDoc}
548 * @since 1.5
549 */
550 @Override
551 public boolean isVarArgs() {
552 return super.isVarArgs();
553 }
554
555 /**
556 * {@inheritDoc}
557 * @jls 13.1 The Form of a Binary
558 * @since 1.5
559 */
560 @Override
561 public boolean isSynthetic() {
562 return super.isSynthetic();
563 }
564
565 /**
566 * Returns {@code true} if this method is a default
567 * method; returns {@code false} otherwise.
568 *
569 * A default method is a public non-abstract instance method, that
570 * is, a non-static method with a body, declared in an interface
571 * type.
572 *
573 * @return true if and only if this method is a default
574 * method as defined by the Java Language Specification.
575 * @since 1.8
576 */
577 public boolean isDefault() {
578 // Default methods are public non-abstract instance methods
579 // declared in an interface.
580 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
581 Modifier.PUBLIC) && getDeclaringClass().isInterface();
582 }
583
584 // NOTE that there is no synchronization used here. It is correct
585 // (though not efficient) to generate more than one MethodAccessor
586 // for a given Method. However, avoiding synchronization will
587 // probably make the implementation more scalable.
588 private MethodAccessor acquireMethodAccessor() {
589 // First check to see if one has been created yet, and take it
590 // if so
591 MethodAccessor tmp = null;
592 if (root != null) tmp = root.getMethodAccessor();
593 if (tmp != null) {
594 methodAccessor = tmp;
595 } else {
596 // Otherwise fabricate one and propagate it up to the root
597 tmp = reflectionFactory.newMethodAccessor(this);
598 setMethodAccessor(tmp);
599 }
600
601 return tmp;
602 }
603
604 // Returns MethodAccessor for this Method object, not looking up
605 // the chain to the root
606 MethodAccessor getMethodAccessor() {
607 return methodAccessor;
608 }
609
610 // Sets the MethodAccessor for this Method object and
611 // (recursively) its root
612 void setMethodAccessor(MethodAccessor accessor) {
613 methodAccessor = accessor;
614 // Propagate up
615 if (root != null) {
616 root.setMethodAccessor(accessor);
617 }
618 }
619
620 /**
621 * Returns the default value for the annotation member represented by
622 * this {@code Method} instance. If the member is of a primitive type,
623 * an instance of the corresponding wrapper type is returned. Returns
624 * null if no default is associated with the member, or if the method
625 * instance does not represent a declared member of an annotation type.
626 *
627 * @return the default value for the annotation member represented
628 * by this {@code Method} instance.
629 * @throws TypeNotPresentException if the annotation is of type
630 * {@link Class} and no definition can be found for the
631 * default class value.
632 * @since 1.5
633 */
634 public Object getDefaultValue() {
635 if (annotationDefault == null)
636 return null;
637 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
638 getReturnType());
639 Object result = AnnotationParser.parseMemberValue(
640 memberType, ByteBuffer.wrap(annotationDefault),
641 SharedSecrets.getJavaLangAccess().
642 getConstantPool(getDeclaringClass()),
643 getDeclaringClass());
644 if (result instanceof sun.reflect.annotation.ExceptionProxy)
645 throw new AnnotationFormatError("Invalid default: " + this);
646 return result;
647 }
648
649 /**
650 * {@inheritDoc}
651 * @throws NullPointerException {@inheritDoc}
652 * @since 1.5
653 */
654 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
655 return super.getAnnotation(annotationClass);
656 }
657
658 /**
659 * {@inheritDoc}
660 * @since 1.5
661 */
662 public Annotation[] getDeclaredAnnotations() {
663 return super.getDeclaredAnnotations();
664 }
665
666 /**
667 * {@inheritDoc}
668 * @since 1.5
669 */
670 @Override
671 public Annotation[][] getParameterAnnotations() {
672 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
673 }
674
675 /**
676 * {@inheritDoc}
677 * @since 1.8
678 */
679 @Override
680 public AnnotatedType getAnnotatedReturnType() {
681 return getAnnotatedReturnType0(getGenericReturnType());
682 }
683
684 @Override
685 void handleParameterNumberMismatch(int resultLength, int numParameters) {
686 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
687 }
688 }