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 sun.reflect.CallerSensitive;
29 import sun.reflect.MethodAccessor;
30 import sun.reflect.Reflection;
31 import sun.reflect.generics.repository.MethodRepository;
32 import sun.reflect.generics.factory.CoreReflectionFactory;
33 import sun.reflect.generics.factory.GenericsFactory;
34 import sun.reflect.generics.scope.MethodScope;
35 import sun.reflect.annotation.AnnotationType;
36 import sun.reflect.annotation.AnnotationParser;
37 import java.lang.annotation.Annotation;
38 import java.lang.annotation.AnnotationFormatError;
39 import java.nio.ByteBuffer;
40 import java.util.Arrays;
41
42 /**
43 * A {@code Method} provides information about, and access to, a single method
44 * on a class or interface. The reflected method may be a class method
45 * or an instance method (including an abstract method).
46 *
47 * <p>A {@code Method} permits widening conversions to occur when matching the
48 * actual parameters to invoke with the underlying method's formal
49 * parameters, but it throws an {@code IllegalArgumentException} if a
50 * narrowing conversion would occur.
51 *
52 * @see Member
53 * @see java.lang.Class
54 * @see java.lang.Class#getMethods()
55 * @see java.lang.Class#getMethod(String, Class[])
56 * @see java.lang.Class#getDeclaredMethods()
57 * @see java.lang.Class#getDeclaredMethod(String, Class[])
58 *
59 * @author Kenneth Russell
60 * @author Nakul Saraiya
61 */
62 public final class Method extends Executable {
63 private Class<?> clazz;
64 private int slot;
65 // This is guaranteed to be interned by the VM in the 1.4
66 // reflection implementation
67 private String name;
68 private Class<?> returnType;
69 private Class<?>[] parameterTypes;
70 private Class<?>[] exceptionTypes;
71 private int modifiers;
72 // Generics and annotations support
73 private transient String signature;
74 // generic info repository; lazily initialized
75 private transient MethodRepository genericInfo;
76 private byte[] annotations;
77 private byte[] parameterAnnotations;
78 private byte[] annotationDefault;
79 private volatile MethodAccessor methodAccessor;
80 // For sharing of MethodAccessors. This branching structure is
81 // currently only two levels deep (i.e., one root Method and
82 // potentially many Method objects pointing to it.)
83 //
84 // If this branching structure would ever contain cycles, deadlocks can
85 // occur in annotation code.
86 private Method root;
87
88 // Generics infrastructure
89 private String getGenericSignature() {return signature;}
90
91 // Accessor for factory
92 private GenericsFactory getFactory() {
93 // create scope and factory
94 return CoreReflectionFactory.make(this, MethodScope.make(this));
95 }
96
97 // Accessor for generic info repository
98 @Override
99 MethodRepository getGenericInfo() {
100 // lazily initialize repository if necessary
101 if (genericInfo == null) {
102 // create and cache generic info repository
103 genericInfo = MethodRepository.make(getGenericSignature(),
104 getFactory());
105 }
106 return genericInfo; //return cached repository
107 }
108
109 /**
110 * Package-private constructor used by ReflectAccess to enable
111 * instantiation of these objects in Java code from the java.lang
112 * package via sun.reflect.LangReflectAccess.
113 */
114 Method(Class<?> declaringClass,
115 String name,
116 Class<?>[] parameterTypes,
117 Class<?> returnType,
118 Class<?>[] checkedExceptions,
119 int modifiers,
120 int slot,
121 String signature,
122 byte[] annotations,
123 byte[] parameterAnnotations,
124 byte[] annotationDefault) {
125 this.clazz = declaringClass;
126 this.name = name;
127 this.parameterTypes = parameterTypes;
128 this.returnType = returnType;
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 this.annotationDefault = annotationDefault;
136 }
137
138 /**
139 * Package-private routine (exposed to java.lang.Class via
140 * ReflectAccess) which returns a copy of this Method. The copy's
141 * "root" field points to this Method.
142 */
143 Method copy() {
144 // This routine enables sharing of MethodAccessor objects
145 // among Method 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 Method");
153
154 Method res = new Method(clazz, name, parameterTypes, returnType,
155 exceptionTypes, modifiers, slot, signature,
156 annotations, parameterAnnotations, annotationDefault);
157 res.root = this;
158 // Might as well eagerly propagate this if already present
159 res.methodAccessor = methodAccessor;
160 return res;
161 }
162
163 /**
164 * Used by Excecutable for annotation sharing.
165 */
166 @Override
167 Executable getRoot() {
168 return root;
169 }
170
171 @Override
172 boolean hasGenericInformation() {
173 return (getGenericSignature() != null);
174 }
175
176 @Override
177 byte[] getAnnotationBytes() {
178 return annotations;
179 }
180
181 /**
182 * Used by java.lang.MethodTable to optimize comparing/locating
183 * method signatures.
184 */
185 boolean parameterTypesEquals(Method other) {
186 int len = parameterTypes.length;
187 if (len != other.parameterTypes.length) {
188 return false;
189 }
190 for (int i = 0; i < len; i++) {
191 if (parameterTypes[i] != other.parameterTypes[i]) {
192 return false;
193 }
194 }
195 return true;
196 }
197
198 int parameterTypesHashCode() {
199 return Arrays.hashCode(parameterTypes);
200 }
201
202 /**
203 * {@inheritDoc}
204 */
205 @Override
206 public Class<?> getDeclaringClass() {
207 return clazz;
208 }
209
210 /**
211 * Returns the name of the method represented by this {@code Method}
212 * object, as a {@code String}.
213 */
214 @Override
215 public String getName() {
216 return name;
217 }
218
219 /**
220 * {@inheritDoc}
221 */
222 @Override
223 public int getModifiers() {
224 return modifiers;
225 }
226
227 /**
228 * {@inheritDoc}
229 * @throws GenericSignatureFormatError {@inheritDoc}
230 * @since 1.5
231 */
232 @Override
233 @SuppressWarnings({"rawtypes", "unchecked"})
234 public TypeVariable<Method>[] getTypeParameters() {
235 if (getGenericSignature() != null)
236 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
237 else
238 return (TypeVariable<Method>[])new TypeVariable[0];
239 }
240
241 /**
242 * Returns a {@code Class} object that represents the formal return type
243 * of the method represented by this {@code Method} object.
244 *
245 * @return the return type for the method this object represents
246 */
247 public Class<?> getReturnType() {
248 return returnType;
249 }
250
251 /**
252 * Returns a {@code Type} object that represents the formal return
253 * type of the method represented by this {@code Method} object.
254 *
255 * <p>If the return type is a parameterized type,
256 * the {@code Type} object returned must accurately reflect
257 * the actual type parameters used in the source code.
258 *
259 * <p>If the return type is a type variable or a parameterized type, it
260 * is created. Otherwise, it is resolved.
261 *
262 * @return a {@code Type} object that represents the formal return
263 * type of the underlying method
264 * @throws GenericSignatureFormatError
265 * if the generic method signature does not conform to the format
266 * specified in
267 * <cite>The Java™ Virtual Machine Specification</cite>
268 * @throws TypeNotPresentException if the underlying method's
269 * return type refers to a non-existent type declaration
270 * @throws MalformedParameterizedTypeException if the
271 * underlying method's return typed refers to a parameterized
272 * type that cannot be instantiated for any reason
273 * @since 1.5
274 */
275 public Type getGenericReturnType() {
276 if (getGenericSignature() != null) {
277 return getGenericInfo().getReturnType();
278 } else { return getReturnType();}
279 }
280
281 /**
282 * {@inheritDoc}
283 */
284 @Override
285 public Class<?>[] getParameterTypes() {
286 return parameterTypes.clone();
287 }
288
289 /**
290 * {@inheritDoc}
291 * @since 1.8
292 */
293 public int getParameterCount() { return parameterTypes.length; }
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[] getGenericParameterTypes() {
305 return super.getGenericParameterTypes();
306 }
307
308 /**
309 * {@inheritDoc}
310 */
311 @Override
312 public Class<?>[] getExceptionTypes() {
313 return exceptionTypes.clone();
314 }
315
316 /**
317 * {@inheritDoc}
318 * @throws GenericSignatureFormatError {@inheritDoc}
319 * @throws TypeNotPresentException {@inheritDoc}
320 * @throws MalformedParameterizedTypeException {@inheritDoc}
321 * @since 1.5
322 */
323 @Override
324 public Type[] getGenericExceptionTypes() {
325 return super.getGenericExceptionTypes();
326 }
327
328 /**
329 * Compares this {@code Method} against the specified object. Returns
330 * true if the objects are the same. Two {@code Methods} are the same if
331 * they were declared by the same class and have the same name
332 * and formal parameter types and return type.
333 */
334 public boolean equals(Object obj) {
335 if (obj != null && obj instanceof Method) {
336 Method other = (Method)obj;
337 if ((getDeclaringClass() == other.getDeclaringClass())
338 && (getName() == other.getName())) {
339 if (!returnType.equals(other.getReturnType()))
340 return false;
341 return equalParamTypes(parameterTypes, other.parameterTypes);
342 }
343 }
344 return false;
345 }
346
347 /**
348 * Returns a hashcode for this {@code Method}. The hashcode is computed
349 * as the exclusive-or of the hashcodes for the underlying
350 * method's declaring class name and the method's name.
351 */
352 public int hashCode() {
353 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
354 }
355
356 /**
357 * Returns a string describing this {@code Method}. The string is
358 * formatted as the method access modifiers, if any, followed by
359 * the method return type, followed by a space, followed by the
360 * class declaring the method, followed by a period, followed by
361 * the method name, followed by a parenthesized, comma-separated
362 * list of the method's formal parameter types. If the method
363 * throws checked exceptions, the parameter list is followed by a
364 * space, followed by the word throws followed by a
365 * comma-separated list of the thrown exception types.
366 * For example:
367 * <pre>
368 * public boolean java.lang.Object.equals(java.lang.Object)
369 * </pre>
370 *
371 * <p>The access modifiers are placed in canonical order as
372 * specified by "The Java Language Specification". This is
373 * {@code public}, {@code protected} or {@code private} first,
374 * and then other modifiers in the following order:
375 * {@code abstract}, {@code default}, {@code static}, {@code final},
376 * {@code synchronized}, {@code native}, {@code strictfp}.
377 *
378 * @return a string describing this {@code Method}
379 *
380 * @jls 8.4.3 Method Modifiers
381 * @jls 9.4 Method Declarations
382 * @jls 9.6.1 Annotation Type Elements
383 */
384 public String toString() {
385 return sharedToString(Modifier.methodModifiers(),
386 isDefault(),
387 parameterTypes,
388 exceptionTypes);
389 }
390
391 @Override
392 void specificToStringHeader(StringBuilder sb) {
393 sb.append(getReturnType().getTypeName()).append(' ');
394 sb.append(getDeclaringClass().getTypeName()).append('.');
395 sb.append(getName());
396 }
397
398 /**
399 * Returns a string describing this {@code Method}, including
400 * type parameters. The string is formatted as the method access
401 * modifiers, if any, followed by an angle-bracketed
402 * comma-separated list of the method's type parameters, if any,
403 * followed by the method's generic return type, followed by a
404 * space, followed by the class declaring the method, followed by
405 * a period, followed by the method name, followed by a
406 * parenthesized, comma-separated list of the method's generic
407 * formal parameter types.
408 *
409 * If this method was declared to take a variable number of
410 * arguments, instead of denoting the last parameter as
411 * "<tt><i>Type</i>[]</tt>", it is denoted as
412 * "<tt><i>Type</i>...</tt>".
413 *
414 * A space is used to separate access modifiers from one another
415 * and from the type parameters or return type. If there are no
416 * type parameters, the type parameter list is elided; if the type
417 * parameter list is present, a space separates the list from the
418 * class name. If the method is declared to throw exceptions, the
419 * parameter list is followed by a space, followed by the word
420 * throws followed by a comma-separated list of the generic thrown
421 * exception types.
422 *
423 * <p>The access modifiers are placed in canonical order as
424 * specified by "The Java Language Specification". This is
425 * {@code public}, {@code protected} or {@code private} first,
426 * and then other modifiers in the following order:
427 * {@code abstract}, {@code default}, {@code static}, {@code final},
428 * {@code synchronized}, {@code native}, {@code strictfp}.
429 *
430 * @return a string describing this {@code Method},
431 * include type parameters
432 *
433 * @since 1.5
434 *
435 * @jls 8.4.3 Method Modifiers
436 * @jls 9.4 Method Declarations
437 * @jls 9.6.1 Annotation Type Elements
438 */
439 @Override
440 public String toGenericString() {
441 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
442 }
443
444 @Override
445 void specificToGenericStringHeader(StringBuilder sb) {
446 Type genRetType = getGenericReturnType();
447 sb.append(genRetType.getTypeName()).append(' ');
448 sb.append(getDeclaringClass().getTypeName()).append('.');
449 sb.append(getName());
450 }
451
452 /**
453 * Invokes the underlying method represented by this {@code Method}
454 * object, on the specified object with the specified parameters.
455 * Individual parameters are automatically unwrapped to match
456 * primitive formal parameters, and both primitive and reference
457 * parameters are subject to method invocation conversions as
458 * necessary.
459 *
460 * <p>If the underlying method is static, then the specified {@code obj}
461 * argument is ignored. It may be null.
462 *
463 * <p>If the number of formal parameters required by the underlying method is
464 * 0, the supplied {@code args} array may be of length 0 or null.
465 *
466 * <p>If the underlying method is an instance method, it is invoked
467 * using dynamic method lookup as documented in The Java Language
468 * Specification, Second Edition, section 15.12.4.4; in particular,
469 * overriding based on the runtime type of the target object will occur.
470 *
471 * <p>If the underlying method is static, the class that declared
472 * the method is initialized if it has not already been initialized.
473 *
474 * <p>If the method completes normally, the value it returns is
475 * returned to the caller of invoke; if the value has a primitive
476 * type, it is first appropriately wrapped in an object. However,
477 * if the value has the type of an array of a primitive type, the
478 * elements of the array are <i>not</i> wrapped in objects; in
479 * other words, an array of primitive type is returned. If the
480 * underlying method return type is void, the invocation returns
481 * null.
482 *
483 * @param obj the object the underlying method is invoked from
484 * @param args the arguments used for the method call
485 * @return the result of dispatching the method represented by
486 * this object on {@code obj} with parameters
487 * {@code args}
488 *
489 * @exception IllegalAccessException if this {@code Method} object
490 * is enforcing Java language access control and the underlying
491 * method is inaccessible.
492 * @exception IllegalArgumentException if the method is an
493 * instance method and the specified object argument
494 * is not an instance of the class or interface
495 * declaring the underlying method (or of a subclass
496 * or implementor thereof); if the number of actual
497 * and formal parameters differ; if an unwrapping
498 * conversion for primitive arguments fails; or if,
499 * after possible unwrapping, a parameter value
500 * cannot be converted to the corresponding formal
501 * parameter type by a method invocation conversion.
502 * @exception InvocationTargetException if the underlying method
503 * throws an exception.
504 * @exception NullPointerException if the specified object is null
505 * and the method is an instance method.
506 * @exception ExceptionInInitializerError if the initialization
507 * provoked by this method fails.
508 */
509 @CallerSensitive
510 public Object invoke(Object obj, Object... args)
511 throws IllegalAccessException, IllegalArgumentException,
512 InvocationTargetException
513 {
514 if (!override) {
515 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
516 Class<?> caller = Reflection.getCallerClass();
517 checkAccess(caller, clazz, obj, modifiers);
518 }
519 }
520 MethodAccessor ma = methodAccessor; // read volatile
521 if (ma == null) {
522 ma = acquireMethodAccessor();
523 }
524 return ma.invoke(obj, args);
525 }
526
527 /**
528 * Returns {@code true} if this method is a bridge
529 * method; returns {@code false} otherwise.
530 *
531 * @return true if and only if this method is a bridge
532 * method as defined by the Java Language Specification.
533 * @since 1.5
534 */
535 public boolean isBridge() {
536 return (getModifiers() & Modifier.BRIDGE) != 0;
537 }
538
539 /**
540 * {@inheritDoc}
541 * @since 1.5
542 */
543 @Override
544 public boolean isVarArgs() {
545 return super.isVarArgs();
546 }
547
548 /**
549 * {@inheritDoc}
550 * @jls 13.1 The Form of a Binary
551 * @since 1.5
552 */
553 @Override
554 public boolean isSynthetic() {
555 return super.isSynthetic();
556 }
557
558 /**
559 * Returns {@code true} if this method is a default
560 * method; returns {@code false} otherwise.
561 *
562 * A default method is a public non-abstract instance method, that
563 * is, a non-static method with a body, declared in an interface
564 * type.
565 *
566 * @return true if and only if this method is a default
567 * method as defined by the Java Language Specification.
568 * @since 1.8
569 */
570 public boolean isDefault() {
571 // Default methods are public non-abstract instance methods
572 // declared in an interface.
573 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
574 Modifier.PUBLIC) && getDeclaringClass().isInterface();
575 }
576
577 // NOTE that there is no synchronization used here. It is correct
578 // (though not efficient) to generate more than one MethodAccessor
579 // for a given Method. However, avoiding synchronization will
580 // probably make the implementation more scalable.
581 private MethodAccessor acquireMethodAccessor() {
582 // First check to see if one has been created yet, and take it
583 // if so
584 MethodAccessor tmp = null;
585 if (root != null) tmp = root.getMethodAccessor();
586 if (tmp != null) {
587 methodAccessor = tmp;
588 } else {
589 // Otherwise fabricate one and propagate it up to the root
590 tmp = reflectionFactory.newMethodAccessor(this);
591 setMethodAccessor(tmp);
592 }
593
594 return tmp;
595 }
596
597 // Returns MethodAccessor for this Method object, not looking up
598 // the chain to the root
599 MethodAccessor getMethodAccessor() {
600 return methodAccessor;
601 }
602
603 // Sets the MethodAccessor for this Method object and
604 // (recursively) its root
605 void setMethodAccessor(MethodAccessor accessor) {
606 methodAccessor = accessor;
607 // Propagate up
608 if (root != null) {
609 root.setMethodAccessor(accessor);
610 }
611 }
612
613 /**
614 * Returns the default value for the annotation member represented by
615 * this {@code Method} instance. If the member is of a primitive type,
616 * an instance of the corresponding wrapper type is returned. Returns
617 * null if no default is associated with the member, or if the method
618 * instance does not represent a declared member of an annotation type.
619 *
620 * @return the default value for the annotation member represented
621 * by this {@code Method} instance.
622 * @throws TypeNotPresentException if the annotation is of type
623 * {@link Class} and no definition can be found for the
624 * default class value.
625 * @since 1.5
626 */
627 public Object getDefaultValue() {
628 if (annotationDefault == null)
629 return null;
630 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
631 getReturnType());
632 Object result = AnnotationParser.parseMemberValue(
633 memberType, ByteBuffer.wrap(annotationDefault),
634 sun.misc.SharedSecrets.getJavaLangAccess().
635 getConstantPool(getDeclaringClass()),
636 getDeclaringClass());
637 if (result instanceof sun.reflect.annotation.ExceptionProxy)
638 throw new AnnotationFormatError("Invalid default: " + this);
639 return result;
640 }
641
642 /**
643 * {@inheritDoc}
644 * @throws NullPointerException {@inheritDoc}
645 * @since 1.5
646 */
647 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
648 return super.getAnnotation(annotationClass);
649 }
650
651 /**
652 * {@inheritDoc}
653 * @since 1.5
654 */
655 public Annotation[] getDeclaredAnnotations() {
656 return super.getDeclaredAnnotations();
657 }
658
659 /**
660 * {@inheritDoc}
661 * @since 1.5
662 */
663 @Override
664 public Annotation[][] getParameterAnnotations() {
665 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
666 }
667
668 /**
669 * {@inheritDoc}
670 * @since 1.8
671 */
672 @Override
673 public AnnotatedType getAnnotatedReturnType() {
674 return getAnnotatedReturnType0(getGenericReturnType());
675 }
676
677 @Override
678 void handleParameterNumberMismatch(int resultLength, int numParameters) {
679 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
680 }
681 }