1 /*
2 * Copyright (c) 1996, 2011, 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.MethodAccessor;
29 import sun.reflect.Reflection;
30 import sun.reflect.generics.repository.MethodRepository;
31 import sun.reflect.generics.factory.CoreReflectionFactory;
32 import sun.reflect.generics.factory.GenericsFactory;
33 import sun.reflect.generics.scope.MethodScope;
34 import sun.reflect.annotation.AnnotationType;
35 import sun.reflect.annotation.AnnotationParser;
36 import java.lang.annotation.Annotation;
37 import java.lang.annotation.AnnotationFormatError;
38 import java.nio.ByteBuffer;
39
40 /**
41 * A {@code Method} provides information about, and access to, a single method
42 * on a class or interface. The reflected method may be a class method
43 * or an instance method (including an abstract method).
44 *
45 * <p>A {@code Method} permits widening conversions to occur when matching the
46 * actual parameters to invoke with the underlying method's formal
47 * parameters, but it throws an {@code IllegalArgumentException} if a
48 * narrowing conversion would occur.
49 *
50 * @see Member
51 * @see java.lang.Class
52 * @see java.lang.Class#getMethods()
53 * @see java.lang.Class#getMethod(String, Class[])
54 * @see java.lang.Class#getDeclaredMethods()
55 * @see java.lang.Class#getDeclaredMethod(String, Class[])
56 *
57 * @author Kenneth Russell
58 * @author Nakul Saraiya
59 */
60 public final class Method extends Executable {
61 private Class<?> clazz;
62 private int slot;
63 // This is guaranteed to be interned by the VM in the 1.4
64 // reflection implementation
65 private String name;
66 private Class<?> returnType;
67 private Class<?>[] parameterTypes;
68 private Class<?>[] exceptionTypes;
69 private int modifiers;
70 // Generics and annotations support
71 private transient String signature;
72 // generic info repository; lazily initialized
73 private transient MethodRepository genericInfo;
74 private byte[] annotations;
75 private byte[] parameterAnnotations;
76 private byte[] annotationDefault;
77 private volatile MethodAccessor methodAccessor;
78 // For sharing of MethodAccessors. This branching structure is
79 // currently only two levels deep (i.e., one root Method and
80 // potentially many Method objects pointing to it.)
81 private Method root;
82
83
84 // Generics infrastructure
85 private String getGenericSignature() {return signature;}
86
87 // Accessor for factory
88 private GenericsFactory getFactory() {
89 // create scope and factory
90 return CoreReflectionFactory.make(this, MethodScope.make(this));
91 }
92
93 // Accessor for generic info repository
94 @Override
95 MethodRepository getGenericInfo() {
96 // lazily initialize repository if necessary
97 if (genericInfo == null) {
98 // create and cache generic info repository
99 genericInfo = MethodRepository.make(getGenericSignature(),
100 getFactory());
101 }
102 return genericInfo; //return cached repository
103 }
104
105 /**
106 * Package-private constructor used by ReflectAccess to enable
107 * instantiation of these objects in Java code from the java.lang
108 * package via sun.reflect.LangReflectAccess.
109 */
110 Method(Class<?> declaringClass,
111 String name,
112 Class<?>[] parameterTypes,
113 Class<?> returnType,
114 Class<?>[] checkedExceptions,
115 int modifiers,
116 int slot,
117 String signature,
118 byte[] annotations,
119 byte[] parameterAnnotations,
120 byte[] annotationDefault) {
121 this.clazz = declaringClass;
122 this.name = name;
123 this.parameterTypes = parameterTypes;
124 this.returnType = returnType;
125 this.exceptionTypes = checkedExceptions;
126 this.modifiers = modifiers;
127 this.slot = slot;
128 this.signature = signature;
129 this.annotations = annotations;
130 this.parameterAnnotations = parameterAnnotations;
131 this.annotationDefault = annotationDefault;
132 }
133
134 /**
135 * Package-private routine (exposed to java.lang.Class via
136 * ReflectAccess) which returns a copy of this Method. The copy's
137 * "root" field points to this Method.
138 */
139 Method copy() {
140 // This routine enables sharing of MethodAccessor objects
141 // among Method objects which refer to the same underlying
142 // method in the VM. (All of this contortion is only necessary
143 // because of the "accessibility" bit in AccessibleObject,
144 // which implicitly requires that new java.lang.reflect
145 // objects be fabricated for each reflective call on Class
146 // objects.)
147 Method res = new Method(clazz, name, parameterTypes, returnType,
148 exceptionTypes, modifiers, slot, signature,
149 annotations, parameterAnnotations, annotationDefault);
150 res.root = this;
151 // Might as well eagerly propagate this if already present
152 res.methodAccessor = methodAccessor;
153 return res;
154 }
155
156 @Override
157 boolean hasGenericInformation() {
158 return (getGenericSignature() != null);
159 }
160
161 @Override
162 byte[] getAnnotationBytes() {
163 return annotations;
164 }
165
166 /**
167 * {@inheritDoc}
168 */
169 @Override
170 public Class<?> getDeclaringClass() {
171 return clazz;
172 }
173
174 /**
175 * Returns the name of the method represented by this {@code Method}
176 * object, as a {@code String}.
177 */
178 @Override
179 public String getName() {
180 return name;
181 }
182
183 /**
184 * {@inheritDoc}
185 */
186 @Override
187 public int getModifiers() {
188 return modifiers;
189 }
190
191 /**
192 * {@inheritDoc}
193 * @throws GenericSignatureFormatError {@inheritDoc}
194 * @since 1.5
195 */
196 @Override
197 public TypeVariable<Method>[] getTypeParameters() {
198 if (getGenericSignature() != null)
199 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
200 else
201 return (TypeVariable<Method>[])new TypeVariable[0];
202 }
203
204 /**
205 * Returns a {@code Class} object that represents the formal return type
206 * of the method represented by this {@code Method} object.
207 *
208 * @return the return type for the method this object represents
209 */
210 public Class<?> getReturnType() {
211 return returnType;
212 }
213
214 /**
215 * Returns a {@code Type} object that represents the formal return
216 * type of the method represented by this {@code Method} object.
217 *
218 * <p>If the return type is a parameterized type,
219 * the {@code Type} object returned must accurately reflect
220 * the actual type parameters used in the source code.
221 *
222 * <p>If the return type is a type variable or a parameterized type, it
223 * is created. Otherwise, it is resolved.
224 *
225 * @return a {@code Type} object that represents the formal return
226 * type of the underlying method
227 * @throws GenericSignatureFormatError
228 * if the generic method signature does not conform to the format
229 * specified in
230 * <cite>The Java™ Virtual Machine Specification</cite>
231 * @throws TypeNotPresentException if the underlying method's
232 * return type refers to a non-existent type declaration
233 * @throws MalformedParameterizedTypeException if the
234 * underlying method's return typed refers to a parameterized
235 * type that cannot be instantiated for any reason
236 * @since 1.5
237 */
238 public Type getGenericReturnType() {
239 if (getGenericSignature() != null) {
240 return getGenericInfo().getReturnType();
241 } else { return getReturnType();}
242 }
243
244 /**
245 * {@inheritDoc}
246 */
247 @Override
248 public Class<?>[] getParameterTypes() {
249 return (Class<?>[]) parameterTypes.clone();
250 }
251
252 /**
253 * {@inheritDoc}
254 * @throws GenericSignatureFormatError {@inheritDoc}
255 * @throws TypeNotPresentException {@inheritDoc}
256 * @throws MalformedParameterizedTypeException {@inheritDoc}
257 * @since 1.5
258 */
259 @Override
260 public Type[] getGenericParameterTypes() {
261 return super.getGenericParameterTypes();
262 }
263
264 /**
265 * {@inheritDoc}
266 */
267 @Override
268 public Class<?>[] getExceptionTypes() {
269 return (Class<?>[]) exceptionTypes.clone();
270 }
271
272 /**
273 * {@inheritDoc}
274 * @throws GenericSignatureFormatError {@inheritDoc}
275 * @throws TypeNotPresentException {@inheritDoc}
276 * @throws MalformedParameterizedTypeException {@inheritDoc}
277 * @since 1.5
278 */
279 @Override
280 public Type[] getGenericExceptionTypes() {
281 return super.getGenericExceptionTypes();
282 }
283
284 /**
285 * Compares this {@code Method} against the specified object. Returns
286 * true if the objects are the same. Two {@code Methods} are the same if
287 * they were declared by the same class and have the same name
288 * and formal parameter types and return type.
289 */
290 public boolean equals(Object obj) {
291 if (obj != null && obj instanceof Method) {
292 Method other = (Method)obj;
293 if ((getDeclaringClass() == other.getDeclaringClass())
294 && (getName() == other.getName())) {
295 if (!returnType.equals(other.getReturnType()))
296 return false;
297 return equalParamTypes(parameterTypes, other.parameterTypes);
298 }
299 }
300 return false;
301 }
302
303 /**
304 * Returns a hashcode for this {@code Method}. The hashcode is computed
305 * as the exclusive-or of the hashcodes for the underlying
306 * method's declaring class name and the method's name.
307 */
308 public int hashCode() {
309 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
310 }
311
312 /**
313 * Returns a string describing this {@code Method}. The string is
314 * formatted as the method access modifiers, if any, followed by
315 * the method return type, followed by a space, followed by the
316 * class declaring the method, followed by a period, followed by
317 * the method name, followed by a parenthesized, comma-separated
318 * list of the method's formal parameter types. If the method
319 * throws checked exceptions, the parameter list is followed by a
320 * space, followed by the word throws followed by a
321 * comma-separated list of the thrown exception types.
322 * For example:
323 * <pre>
324 * public boolean java.lang.Object.equals(java.lang.Object)
325 * </pre>
326 *
327 * <p>The access modifiers are placed in canonical order as
328 * specified by "The Java Language Specification". This is
329 * {@code public}, {@code protected} or {@code private} first,
330 * and then other modifiers in the following order:
331 * {@code abstract}, {@code static}, {@code final},
332 * {@code synchronized}, {@code native}, {@code strictfp}.
333 */
334 public String toString() {
335 return sharedToString(Modifier.methodModifiers(),
336 parameterTypes,
337 exceptionTypes);
338 }
339
340 @Override
341 void specificToStringHeader(StringBuilder sb) {
342 sb.append(Field.getTypeName(getReturnType())).append(' ');
343 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
344 sb.append(getName());
345 }
346
347 /**
348 * Returns a string describing this {@code Method}, including
349 * type parameters. The string is formatted as the method access
350 * modifiers, if any, followed by an angle-bracketed
351 * comma-separated list of the method's type parameters, if any,
352 * followed by the method's generic return type, followed by a
353 * space, followed by the class declaring the method, followed by
354 * a period, followed by the method name, followed by a
355 * parenthesized, comma-separated list of the method's generic
356 * formal parameter types.
357 *
358 * If this method was declared to take a variable number of
359 * arguments, instead of denoting the last parameter as
360 * "<tt><i>Type</i>[]</tt>", it is denoted as
361 * "<tt><i>Type</i>...</tt>".
362 *
363 * A space is used to separate access modifiers from one another
364 * and from the type parameters or return type. If there are no
365 * type parameters, the type parameter list is elided; if the type
366 * parameter list is present, a space separates the list from the
367 * class name. If the method is declared to throw exceptions, the
368 * parameter list is followed by a space, followed by the word
369 * throws followed by a comma-separated list of the generic thrown
370 * exception types. If there are no type parameters, the type
371 * parameter list is elided.
372 *
373 * <p>The access modifiers are placed in canonical order as
374 * specified by "The Java Language Specification". This is
375 * {@code public}, {@code protected} or {@code private} first,
376 * and then other modifiers in the following order:
377 * {@code abstract}, {@code static}, {@code final},
378 * {@code synchronized}, {@code native}, {@code strictfp}.
379 *
380 * @return a string describing this {@code Method},
381 * include type parameters
382 *
383 * @since 1.5
384 */
385 @Override
386 public String toGenericString() {
387 return sharedToGenericString(Modifier.methodModifiers());
388 }
389
390 @Override
391 void specificToGenericStringHeader(StringBuilder sb) {
392 Type genRetType = getGenericReturnType();
393 sb.append( ((genRetType instanceof Class<?>)?
394 Field.getTypeName((Class<?>)genRetType):genRetType.toString()))
395 .append(' ');
396
397 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
398 sb.append(getName());
399 }
400
401 /**
402 * Invokes the underlying method represented by this {@code Method}
403 * object, on the specified object with the specified parameters.
404 * Individual parameters are automatically unwrapped to match
405 * primitive formal parameters, and both primitive and reference
406 * parameters are subject to method invocation conversions as
407 * necessary.
408 *
409 * <p>If the underlying method is static, then the specified {@code obj}
410 * argument is ignored. It may be null.
411 *
412 * <p>If the number of formal parameters required by the underlying method is
413 * 0, the supplied {@code args} array may be of length 0 or null.
414 *
415 * <p>If the underlying method is an instance method, it is invoked
416 * using dynamic method lookup as documented in The Java Language
417 * Specification, Second Edition, section 15.12.4.4; in particular,
418 * overriding based on the runtime type of the target object will occur.
419 *
420 * <p>If the underlying method is static, the class that declared
421 * the method is initialized if it has not already been initialized.
422 *
423 * <p>If the method completes normally, the value it returns is
424 * returned to the caller of invoke; if the value has a primitive
425 * type, it is first appropriately wrapped in an object. However,
426 * if the value has the type of an array of a primitive type, the
427 * elements of the array are <i>not</i> wrapped in objects; in
428 * other words, an array of primitive type is returned. If the
429 * underlying method return type is void, the invocation returns
430 * null.
431 *
432 * @param obj the object the underlying method is invoked from
433 * @param args the arguments used for the method call
434 * @return the result of dispatching the method represented by
435 * this object on {@code obj} with parameters
436 * {@code args}
437 *
438 * @exception IllegalAccessException if this {@code Method} object
439 * is enforcing Java language access control and the underlying
440 * method is inaccessible.
441 * @exception IllegalArgumentException if the method is an
442 * instance method and the specified object argument
443 * is not an instance of the class or interface
444 * declaring the underlying method (or of a subclass
445 * or implementor thereof); if the number of actual
446 * and formal parameters differ; if an unwrapping
447 * conversion for primitive arguments fails; or if,
448 * after possible unwrapping, a parameter value
449 * cannot be converted to the corresponding formal
450 * parameter type by a method invocation conversion.
451 * @exception InvocationTargetException if the underlying method
452 * throws an exception.
453 * @exception NullPointerException if the specified object is null
454 * and the method is an instance method.
455 * @exception ExceptionInInitializerError if the initialization
456 * provoked by this method fails.
457 */
458 public Object invoke(Object obj, Object... args)
459 throws IllegalAccessException, IllegalArgumentException,
460 InvocationTargetException
461 {
462 if (!override) {
463 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
464 Class<?> caller = Reflection.getCallerClass(1);
465
466 checkAccess(caller, clazz, obj, modifiers);
467 }
468 }
469 MethodAccessor ma = methodAccessor; // read volatile
470 if (ma == null) {
471 ma = acquireMethodAccessor();
472 }
473 return ma.invoke(obj, args);
474 }
475
476 /**
477 * Returns {@code true} if this method is a bridge
478 * method; returns {@code false} otherwise.
479 *
480 * @return true if and only if this method is a bridge
481 * method as defined by the Java Language Specification.
482 * @since 1.5
483 */
484 public boolean isBridge() {
485 return (getModifiers() & Modifier.BRIDGE) != 0;
486 }
487
488 /**
489 * {@inheritDoc}
490 * @since 1.5
491 */
492 @Override
493 public boolean isVarArgs() {
494 return super.isVarArgs();
495 }
496
497 /**
498 * {@inheritDoc}
499 * @since 1.5
500 */
501 @Override
502 public boolean isSynthetic() {
503 return super.isSynthetic();
504 }
505
506 // NOTE that there is no synchronization used here. It is correct
507 // (though not efficient) to generate more than one MethodAccessor
508 // for a given Method. However, avoiding synchronization will
509 // probably make the implementation more scalable.
510 private MethodAccessor acquireMethodAccessor() {
511 // First check to see if one has been created yet, and take it
512 // if so
513 MethodAccessor tmp = null;
514 if (root != null) tmp = root.getMethodAccessor();
515 if (tmp != null) {
516 methodAccessor = tmp;
517 } else {
518 // Otherwise fabricate one and propagate it up to the root
519 tmp = reflectionFactory.newMethodAccessor(this);
520 setMethodAccessor(tmp);
521 }
522
523 return tmp;
524 }
525
526 // Returns MethodAccessor for this Method object, not looking up
527 // the chain to the root
528 MethodAccessor getMethodAccessor() {
529 return methodAccessor;
530 }
531
532 // Sets the MethodAccessor for this Method object and
533 // (recursively) its root
534 void setMethodAccessor(MethodAccessor accessor) {
535 methodAccessor = accessor;
536 // Propagate up
537 if (root != null) {
538 root.setMethodAccessor(accessor);
539 }
540 }
541
542 /**
543 * Returns the default value for the annotation member represented by
544 * this {@code Method} instance. If the member is of a primitive type,
545 * an instance of the corresponding wrapper type is returned. Returns
546 * null if no default is associated with the member, or if the method
547 * instance does not represent a declared member of an annotation type.
548 *
549 * @return the default value for the annotation member represented
550 * by this {@code Method} instance.
551 * @throws TypeNotPresentException if the annotation is of type
552 * {@link Class} and no definition can be found for the
553 * default class value.
554 * @since 1.5
555 */
556 public Object getDefaultValue() {
557 if (annotationDefault == null)
558 return null;
559 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
560 getReturnType());
561 Object result = AnnotationParser.parseMemberValue(
562 memberType, ByteBuffer.wrap(annotationDefault),
563 sun.misc.SharedSecrets.getJavaLangAccess().
564 getConstantPool(getDeclaringClass()),
565 getDeclaringClass());
566 if (result instanceof sun.reflect.annotation.ExceptionProxy)
567 throw new AnnotationFormatError("Invalid default: " + this);
568 return result;
569 }
570
571 /**
572 * {@inheritDoc}
573 * @throws NullPointerException {@inheritDoc}
574 * @since 1.5
575 */
576 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
577 return super.getAnnotation(annotationClass);
578 }
579
580 /**
581 * {@inheritDoc}
582 * @since 1.5
583 */
584 public Annotation[] getDeclaredAnnotations() {
585 return super.getDeclaredAnnotations();
586 }
587
588 /**
589 * {@inheritDoc}
590 * @since 1.5
591 */
592 @Override
593 public Annotation[][] getParameterAnnotations() {
594 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
595 }
596
597 @Override
598 void handleParameterNumberMismatch(int resultLength, int numParameters) {
599 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
600 }
601 }