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 */
382 public String toString() {
383 return sharedToString(Modifier.methodModifiers(),
384 isDefault(),
385 parameterTypes,
386 exceptionTypes);
387 }
388
389 @Override
390 void specificToStringHeader(StringBuilder sb) {
391 sb.append(getReturnType().getTypeName()).append(' ');
392 sb.append(getDeclaringClass().getTypeName()).append('.');
393 sb.append(getName());
394 }
395
396 /**
397 * Returns a string describing this {@code Method}, including
398 * type parameters. The string is formatted as the method access
399 * modifiers, if any, followed by an angle-bracketed
400 * comma-separated list of the method's type parameters, if any,
401 * followed by the method's generic return type, followed by a
402 * space, followed by the class declaring the method, followed by
403 * a period, followed by the method name, followed by a
404 * parenthesized, comma-separated list of the method's generic
405 * formal parameter types.
406 *
407 * If this method was declared to take a variable number of
408 * arguments, instead of denoting the last parameter as
409 * "<tt><i>Type</i>[]</tt>", it is denoted as
410 * "<tt><i>Type</i>...</tt>".
411 *
412 * A space is used to separate access modifiers from one another
413 * and from the type parameters or return type. If there are no
414 * type parameters, the type parameter list is elided; if the type
415 * parameter list is present, a space separates the list from the
416 * class name. If the method is declared to throw exceptions, the
417 * parameter list is followed by a space, followed by the word
418 * throws followed by a comma-separated list of the generic thrown
419 * exception types.
420 *
421 * <p>The access modifiers are placed in canonical order as
422 * specified by "The Java Language Specification". This is
423 * {@code public}, {@code protected} or {@code private} first,
424 * and then other modifiers in the following order:
425 * {@code abstract}, {@code default}, {@code static}, {@code final},
426 * {@code synchronized}, {@code native}, {@code strictfp}.
427 *
428 * @return a string describing this {@code Method},
429 * include type parameters
430 *
431 * @since 1.5
432 *
433 * @jls 8.4.3 Method Modifiers
434 */
435 @Override
436 public String toGenericString() {
437 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
438 }
439
440 @Override
441 void specificToGenericStringHeader(StringBuilder sb) {
442 Type genRetType = getGenericReturnType();
443 sb.append(genRetType.getTypeName()).append(' ');
444 sb.append(getDeclaringClass().getTypeName()).append('.');
445 sb.append(getName());
446 }
447
448 /**
449 * Invokes the underlying method represented by this {@code Method}
450 * object, on the specified object with the specified parameters.
451 * Individual parameters are automatically unwrapped to match
452 * primitive formal parameters, and both primitive and reference
453 * parameters are subject to method invocation conversions as
454 * necessary.
455 *
456 * <p>If the underlying method is static, then the specified {@code obj}
457 * argument is ignored. It may be null.
458 *
459 * <p>If the number of formal parameters required by the underlying method is
460 * 0, the supplied {@code args} array may be of length 0 or null.
461 *
462 * <p>If the underlying method is an instance method, it is invoked
463 * using dynamic method lookup as documented in The Java Language
464 * Specification, Second Edition, section 15.12.4.4; in particular,
465 * overriding based on the runtime type of the target object will occur.
466 *
467 * <p>If the underlying method is static, the class that declared
468 * the method is initialized if it has not already been initialized.
469 *
470 * <p>If the method completes normally, the value it returns is
471 * returned to the caller of invoke; if the value has a primitive
472 * type, it is first appropriately wrapped in an object. However,
473 * if the value has the type of an array of a primitive type, the
474 * elements of the array are <i>not</i> wrapped in objects; in
475 * other words, an array of primitive type is returned. If the
476 * underlying method return type is void, the invocation returns
477 * null.
478 *
479 * @param obj the object the underlying method is invoked from
480 * @param args the arguments used for the method call
481 * @return the result of dispatching the method represented by
482 * this object on {@code obj} with parameters
483 * {@code args}
484 *
485 * @exception IllegalAccessException if this {@code Method} object
486 * is enforcing Java language access control and the underlying
487 * method is inaccessible.
488 * @exception IllegalArgumentException if the method is an
489 * instance method and the specified object argument
490 * is not an instance of the class or interface
491 * declaring the underlying method (or of a subclass
492 * or implementor thereof); if the number of actual
493 * and formal parameters differ; if an unwrapping
494 * conversion for primitive arguments fails; or if,
495 * after possible unwrapping, a parameter value
496 * cannot be converted to the corresponding formal
497 * parameter type by a method invocation conversion.
498 * @exception InvocationTargetException if the underlying method
499 * throws an exception.
500 * @exception NullPointerException if the specified object is null
501 * and the method is an instance method.
502 * @exception ExceptionInInitializerError if the initialization
503 * provoked by this method fails.
504 */
505 @CallerSensitive
506 public Object invoke(Object obj, Object... args)
507 throws IllegalAccessException, IllegalArgumentException,
508 InvocationTargetException
509 {
510 if (!override) {
511 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
512 Class<?> caller = Reflection.getCallerClass();
513 checkAccess(caller, clazz, obj, modifiers);
514 }
515 }
516 MethodAccessor ma = methodAccessor; // read volatile
517 if (ma == null) {
518 ma = acquireMethodAccessor();
519 }
520 return ma.invoke(obj, args);
521 }
522
523 /**
524 * Returns {@code true} if this method is a bridge
525 * method; returns {@code false} otherwise.
526 *
527 * @return true if and only if this method is a bridge
528 * method as defined by the Java Language Specification.
529 * @since 1.5
530 */
531 public boolean isBridge() {
532 return (getModifiers() & Modifier.BRIDGE) != 0;
533 }
534
535 /**
536 * {@inheritDoc}
537 * @since 1.5
538 */
539 @Override
540 public boolean isVarArgs() {
541 return super.isVarArgs();
542 }
543
544 /**
545 * {@inheritDoc}
546 * @jls 13.1 The Form of a Binary
547 * @since 1.5
548 */
549 @Override
550 public boolean isSynthetic() {
551 return super.isSynthetic();
552 }
553
554 /**
555 * Returns {@code true} if this method is a default
556 * method; returns {@code false} otherwise.
557 *
558 * A default method is a public non-abstract instance method, that
559 * is, a non-static method with a body, declared in an interface
560 * type.
561 *
562 * @return true if and only if this method is a default
563 * method as defined by the Java Language Specification.
564 * @since 1.8
565 */
566 public boolean isDefault() {
567 // Default methods are public non-abstract instance methods
568 // declared in an interface.
569 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
570 Modifier.PUBLIC) && getDeclaringClass().isInterface();
571 }
572
573 // NOTE that there is no synchronization used here. It is correct
574 // (though not efficient) to generate more than one MethodAccessor
575 // for a given Method. However, avoiding synchronization will
576 // probably make the implementation more scalable.
577 private MethodAccessor acquireMethodAccessor() {
578 // First check to see if one has been created yet, and take it
579 // if so
580 MethodAccessor tmp = null;
581 if (root != null) tmp = root.getMethodAccessor();
582 if (tmp != null) {
583 methodAccessor = tmp;
584 } else {
585 // Otherwise fabricate one and propagate it up to the root
586 tmp = reflectionFactory.newMethodAccessor(this);
587 setMethodAccessor(tmp);
588 }
589
590 return tmp;
591 }
592
593 // Returns MethodAccessor for this Method object, not looking up
594 // the chain to the root
595 MethodAccessor getMethodAccessor() {
596 return methodAccessor;
597 }
598
599 // Sets the MethodAccessor for this Method object and
600 // (recursively) its root
601 void setMethodAccessor(MethodAccessor accessor) {
602 methodAccessor = accessor;
603 // Propagate up
604 if (root != null) {
605 root.setMethodAccessor(accessor);
606 }
607 }
608
609 /**
610 * Returns the default value for the annotation member represented by
611 * this {@code Method} instance. If the member is of a primitive type,
612 * an instance of the corresponding wrapper type is returned. Returns
613 * null if no default is associated with the member, or if the method
614 * instance does not represent a declared member of an annotation type.
615 *
616 * @return the default value for the annotation member represented
617 * by this {@code Method} instance.
618 * @throws TypeNotPresentException if the annotation is of type
619 * {@link Class} and no definition can be found for the
620 * default class value.
621 * @since 1.5
622 */
623 public Object getDefaultValue() {
624 if (annotationDefault == null)
625 return null;
626 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
627 getReturnType());
628 Object result = AnnotationParser.parseMemberValue(
629 memberType, ByteBuffer.wrap(annotationDefault),
630 sun.misc.SharedSecrets.getJavaLangAccess().
631 getConstantPool(getDeclaringClass()),
632 getDeclaringClass());
633 if (result instanceof sun.reflect.annotation.ExceptionProxy)
634 throw new AnnotationFormatError("Invalid default: " + this);
635 return result;
636 }
637
638 /**
639 * {@inheritDoc}
640 * @throws NullPointerException {@inheritDoc}
641 * @since 1.5
642 */
643 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
644 return super.getAnnotation(annotationClass);
645 }
646
647 /**
648 * {@inheritDoc}
649 * @since 1.5
650 */
651 public Annotation[] getDeclaredAnnotations() {
652 return super.getDeclaredAnnotations();
653 }
654
655 /**
656 * {@inheritDoc}
657 * @since 1.5
658 */
659 @Override
660 public Annotation[][] getParameterAnnotations() {
661 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
662 }
663
664 /**
665 * {@inheritDoc}
666 * @since 1.8
667 */
668 @Override
669 public AnnotatedType getAnnotatedReturnType() {
670 return getAnnotatedReturnType0(getGenericReturnType());
671 }
672
673 @Override
674 void handleParameterNumberMismatch(int resultLength, int numParameters) {
675 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
676 }
677 }