1 /*
2 * Copyright (c) 1996, 2012, 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 // This is set by the vm at Method creation
83 private byte[] typeAnnotations;
84
85 // Generics infrastructure
86 private String getGenericSignature() {return signature;}
87
88 // Accessor for factory
89 private GenericsFactory getFactory() {
90 // create scope and factory
91 return CoreReflectionFactory.make(this, MethodScope.make(this));
92 }
93
94 // Accessor for generic info repository
95 @Override
96 MethodRepository getGenericInfo() {
97 // lazily initialize repository if necessary
98 if (genericInfo == null) {
99 // create and cache generic info repository
100 genericInfo = MethodRepository.make(getGenericSignature(),
101 getFactory());
102 }
103 return genericInfo; //return cached repository
104 }
105
106 /**
107 * Package-private constructor used by ReflectAccess to enable
108 * instantiation of these objects in Java code from the java.lang
109 * package via sun.reflect.LangReflectAccess.
110 */
111 Method(Class<?> declaringClass,
112 String name,
113 Class<?>[] parameterTypes,
114 Class<?> returnType,
115 Class<?>[] checkedExceptions,
116 int modifiers,
117 int slot,
118 String signature,
119 byte[] annotations,
120 byte[] parameterAnnotations,
121 byte[] annotationDefault) {
122 this.clazz = declaringClass;
123 this.name = name;
124 this.parameterTypes = parameterTypes;
125 this.returnType = returnType;
126 this.exceptionTypes = checkedExceptions;
127 this.modifiers = modifiers;
128 this.slot = slot;
129 this.signature = signature;
130 this.annotations = annotations;
131 this.parameterAnnotations = parameterAnnotations;
132 this.annotationDefault = annotationDefault;
133 }
134
135 /**
136 * Package-private routine (exposed to java.lang.Class via
137 * ReflectAccess) which returns a copy of this Method. The copy's
138 * "root" field points to this Method.
139 */
140 Method copy() {
141 // This routine enables sharing of MethodAccessor objects
142 // among Method objects which refer to the same underlying
143 // method in the VM. (All of this contortion is only necessary
144 // because of the "accessibility" bit in AccessibleObject,
145 // which implicitly requires that new java.lang.reflect
146 // objects be fabricated for each reflective call on Class
147 // objects.)
148 Method res = new Method(clazz, name, parameterTypes, returnType,
149 exceptionTypes, modifiers, slot, signature,
150 annotations, parameterAnnotations, annotationDefault);
151 res.root = this;
152 // Might as well eagerly propagate this if already present
153 res.methodAccessor = methodAccessor;
154
155 res.typeAnnotations = typeAnnotations;
156 return res;
157 }
158
159 @Override
160 boolean hasGenericInformation() {
161 return (getGenericSignature() != null);
162 }
163
164 @Override
165 byte[] getAnnotationBytes() {
166 return annotations;
167 }
168
169 /**
170 * {@inheritDoc}
171 */
172 @Override
173 public Class<?> getDeclaringClass() {
174 return clazz;
175 }
176
177 /**
178 * Returns the name of the method represented by this {@code Method}
179 * object, as a {@code String}.
180 */
181 @Override
182 public String getName() {
183 return name;
184 }
185
186 /**
187 * {@inheritDoc}
188 */
189 @Override
190 public int getModifiers() {
191 return modifiers;
192 }
193
194 /**
195 * {@inheritDoc}
196 * @throws GenericSignatureFormatError {@inheritDoc}
197 * @since 1.5
198 */
199 @Override
200 @SuppressWarnings({"rawtypes", "unchecked"})
201 public TypeVariable<Method>[] getTypeParameters() {
202 if (getGenericSignature() != null)
203 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
204 else
205 return (TypeVariable<Method>[])new TypeVariable[0];
206 }
207
208 /**
209 * Returns a {@code Class} object that represents the formal return type
210 * of the method represented by this {@code Method} object.
211 *
212 * @return the return type for the method this object represents
213 */
214 public Class<?> getReturnType() {
215 return returnType;
216 }
217
218 /**
219 * Returns a {@code Type} object that represents the formal return
220 * type of the method represented by this {@code Method} object.
221 *
222 * <p>If the return type is a parameterized type,
223 * the {@code Type} object returned must accurately reflect
224 * the actual type parameters used in the source code.
225 *
226 * <p>If the return type is a type variable or a parameterized type, it
227 * is created. Otherwise, it is resolved.
228 *
229 * @return a {@code Type} object that represents the formal return
230 * type of the underlying method
231 * @throws GenericSignatureFormatError
232 * if the generic method signature does not conform to the format
233 * specified in
234 * <cite>The Java™ Virtual Machine Specification</cite>
235 * @throws TypeNotPresentException if the underlying method's
236 * return type refers to a non-existent type declaration
237 * @throws MalformedParameterizedTypeException if the
238 * underlying method's return typed refers to a parameterized
239 * type that cannot be instantiated for any reason
240 * @since 1.5
241 */
242 public Type getGenericReturnType() {
243 if (getGenericSignature() != null) {
244 return getGenericInfo().getReturnType();
245 } else { return getReturnType();}
246 }
247
248 /**
249 * {@inheritDoc}
250 */
251 @Override
252 public Class<?>[] getParameterTypes() {
253 return parameterTypes.clone();
254 }
255
256 /**
257 * {@inheritDoc}
258 */
259 public int getParameterCount() { return parameterTypes.length; }
260
261
262 /**
263 * {@inheritDoc}
264 * @throws GenericSignatureFormatError {@inheritDoc}
265 * @throws TypeNotPresentException {@inheritDoc}
266 * @throws MalformedParameterizedTypeException {@inheritDoc}
267 * @since 1.5
268 */
269 @Override
270 public Type[] getGenericParameterTypes() {
271 return super.getGenericParameterTypes();
272 }
273
274 /**
275 * {@inheritDoc}
276 */
277 @Override
278 public Class<?>[] getExceptionTypes() {
279 return exceptionTypes.clone();
280 }
281
282 /**
283 * {@inheritDoc}
284 * @throws GenericSignatureFormatError {@inheritDoc}
285 * @throws TypeNotPresentException {@inheritDoc}
286 * @throws MalformedParameterizedTypeException {@inheritDoc}
287 * @since 1.5
288 */
289 @Override
290 public Type[] getGenericExceptionTypes() {
291 return super.getGenericExceptionTypes();
292 }
293
294 /**
295 * Compares this {@code Method} against the specified object. Returns
296 * true if the objects are the same. Two {@code Methods} are the same if
297 * they were declared by the same class and have the same name
298 * and formal parameter types and return type.
299 */
300 public boolean equals(Object obj) {
301 if (obj != null && obj instanceof Method) {
302 Method other = (Method)obj;
303 if ((getDeclaringClass() == other.getDeclaringClass())
304 && (getName() == other.getName())) {
305 if (!returnType.equals(other.getReturnType()))
306 return false;
307 return equalParamTypes(parameterTypes, other.parameterTypes);
308 }
309 }
310 return false;
311 }
312
313 /**
314 * Returns a hashcode for this {@code Method}. The hashcode is computed
315 * as the exclusive-or of the hashcodes for the underlying
316 * method's declaring class name and the method's name.
317 */
318 public int hashCode() {
319 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
320 }
321
322 /**
323 * Returns a string describing this {@code Method}. The string is
324 * formatted as the method access modifiers, if any, followed by
325 * the method return type, followed by a space, followed by the
326 * class declaring the method, followed by a period, followed by
327 * the method name, followed by a parenthesized, comma-separated
328 * list of the method's formal parameter types. If the method
329 * throws checked exceptions, the parameter list is followed by a
330 * space, followed by the word throws followed by a
331 * comma-separated list of the thrown exception types.
332 * For example:
333 * <pre>
334 * public boolean java.lang.Object.equals(java.lang.Object)
335 * </pre>
336 *
337 * <p>The access modifiers are placed in canonical order as
338 * specified by "The Java Language Specification". This is
339 * {@code public}, {@code protected} or {@code private} first,
340 * and then other modifiers in the following order:
341 * {@code abstract}, {@code static}, {@code final},
342 * {@code synchronized}, {@code native}, {@code strictfp}.
343 */
344 public String toString() {
345 return sharedToString(Modifier.methodModifiers(),
346 parameterTypes,
347 exceptionTypes);
348 }
349
350 @Override
351 void specificToStringHeader(StringBuilder sb) {
352 sb.append(Field.getTypeName(getReturnType())).append(' ');
353 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
354 sb.append(getName());
355 }
356
357 /**
358 * Returns a string describing this {@code Method}, including
359 * type parameters. The string is formatted as the method access
360 * modifiers, if any, followed by an angle-bracketed
361 * comma-separated list of the method's type parameters, if any,
362 * followed by the method's generic return type, followed by a
363 * space, followed by the class declaring the method, followed by
364 * a period, followed by the method name, followed by a
365 * parenthesized, comma-separated list of the method's generic
366 * formal parameter types.
367 *
368 * If this method was declared to take a variable number of
369 * arguments, instead of denoting the last parameter as
370 * "<tt><i>Type</i>[]</tt>", it is denoted as
371 * "<tt><i>Type</i>...</tt>".
372 *
373 * A space is used to separate access modifiers from one another
374 * and from the type parameters or return type. If there are no
375 * type parameters, the type parameter list is elided; if the type
376 * parameter list is present, a space separates the list from the
377 * class name. If the method is declared to throw exceptions, the
378 * parameter list is followed by a space, followed by the word
379 * throws followed by a comma-separated list of the generic thrown
380 * exception types. If there are no type parameters, the type
381 * parameter list is elided.
382 *
383 * <p>The access modifiers are placed in canonical order as
384 * specified by "The Java Language Specification". This is
385 * {@code public}, {@code protected} or {@code private} first,
386 * and then other modifiers in the following order:
387 * {@code abstract}, {@code static}, {@code final},
388 * {@code synchronized}, {@code native}, {@code strictfp}.
389 *
390 * @return a string describing this {@code Method},
391 * include type parameters
392 *
393 * @since 1.5
394 */
395 @Override
396 public String toGenericString() {
397 return sharedToGenericString(Modifier.methodModifiers());
398 }
399
400 @Override
401 void specificToGenericStringHeader(StringBuilder sb) {
402 Type genRetType = getGenericReturnType();
403 sb.append( ((genRetType instanceof Class<?>)?
404 Field.getTypeName((Class<?>)genRetType):genRetType.toString()))
405 .append(' ');
406
407 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
408 sb.append(getName());
409 }
410
411 /**
412 * Invokes the underlying method represented by this {@code Method}
413 * object, on the specified object with the specified parameters.
414 * Individual parameters are automatically unwrapped to match
415 * primitive formal parameters, and both primitive and reference
416 * parameters are subject to method invocation conversions as
417 * necessary.
418 *
419 * <p>If the underlying method is static, then the specified {@code obj}
420 * argument is ignored. It may be null.
421 *
422 * <p>If the number of formal parameters required by the underlying method is
423 * 0, the supplied {@code args} array may be of length 0 or null.
424 *
425 * <p>If the underlying method is an instance method, it is invoked
426 * using dynamic method lookup as documented in The Java Language
427 * Specification, Second Edition, section 15.12.4.4; in particular,
428 * overriding based on the runtime type of the target object will occur.
429 *
430 * <p>If the underlying method is static, the class that declared
431 * the method is initialized if it has not already been initialized.
432 *
433 * <p>If the method completes normally, the value it returns is
434 * returned to the caller of invoke; if the value has a primitive
435 * type, it is first appropriately wrapped in an object. However,
436 * if the value has the type of an array of a primitive type, the
437 * elements of the array are <i>not</i> wrapped in objects; in
438 * other words, an array of primitive type is returned. If the
439 * underlying method return type is void, the invocation returns
440 * null.
441 *
442 * @param obj the object the underlying method is invoked from
443 * @param args the arguments used for the method call
444 * @return the result of dispatching the method represented by
445 * this object on {@code obj} with parameters
446 * {@code args}
447 *
448 * @exception IllegalAccessException if this {@code Method} object
449 * is enforcing Java language access control and the underlying
450 * method is inaccessible.
451 * @exception IllegalArgumentException if the method is an
452 * instance method and the specified object argument
453 * is not an instance of the class or interface
454 * declaring the underlying method (or of a subclass
455 * or implementor thereof); if the number of actual
456 * and formal parameters differ; if an unwrapping
457 * conversion for primitive arguments fails; or if,
458 * after possible unwrapping, a parameter value
459 * cannot be converted to the corresponding formal
460 * parameter type by a method invocation conversion.
461 * @exception InvocationTargetException if the underlying method
462 * throws an exception.
463 * @exception NullPointerException if the specified object is null
464 * and the method is an instance method.
465 * @exception ExceptionInInitializerError if the initialization
466 * provoked by this method fails.
467 */
468 public Object invoke(Object obj, Object... args)
469 throws IllegalAccessException, IllegalArgumentException,
470 InvocationTargetException
471 {
472 if (!override) {
473 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
474 Class<?> caller = Reflection.getCallerClass(1);
475
476 checkAccess(caller, clazz, obj, modifiers);
477 }
478 }
479 MethodAccessor ma = methodAccessor; // read volatile
480 if (ma == null) {
481 ma = acquireMethodAccessor();
482 }
483 return ma.invoke(obj, args);
484 }
485
486 /**
487 * Returns {@code true} if this method is a bridge
488 * method; returns {@code false} otherwise.
489 *
490 * @return true if and only if this method is a bridge
491 * method as defined by the Java Language Specification.
492 * @since 1.5
493 */
494 public boolean isBridge() {
495 return (getModifiers() & Modifier.BRIDGE) != 0;
496 }
497
498 /**
499 * {@inheritDoc}
500 * @since 1.5
501 */
502 @Override
503 public boolean isVarArgs() {
504 return super.isVarArgs();
505 }
506
507 /**
508 * {@inheritDoc}
509 * @jls 13.1 The Form of a Binary
510 * @since 1.5
511 */
512 @Override
513 public boolean isSynthetic() {
514 return super.isSynthetic();
515 }
516
517 /**
518 * Returns {@code true} if this method is a default
519 * method; returns {@code false} otherwise.
520 *
521 * A default method is a non-abstract method, that is, a method
522 * with a body, declared in an interface type.
523 *
524 * @return true if and only if this method is a default
525 * method as defined by the Java Language Specification.
526 * @since 1.8
527 */
528 public boolean isDefault() {
529 return (getModifiers() & Modifier.ABSTRACT) == 0 &&
530 getDeclaringClass().isInterface();
531 }
532
533 // NOTE that there is no synchronization used here. It is correct
534 // (though not efficient) to generate more than one MethodAccessor
535 // for a given Method. However, avoiding synchronization will
536 // probably make the implementation more scalable.
537 private MethodAccessor acquireMethodAccessor() {
538 // First check to see if one has been created yet, and take it
539 // if so
540 MethodAccessor tmp = null;
541 if (root != null) tmp = root.getMethodAccessor();
542 if (tmp != null) {
543 methodAccessor = tmp;
544 } else {
545 // Otherwise fabricate one and propagate it up to the root
546 tmp = reflectionFactory.newMethodAccessor(this);
547 setMethodAccessor(tmp);
548 }
549
550 return tmp;
551 }
552
553 // Returns MethodAccessor for this Method object, not looking up
554 // the chain to the root
555 MethodAccessor getMethodAccessor() {
556 return methodAccessor;
557 }
558
559 // Sets the MethodAccessor for this Method object and
560 // (recursively) its root
561 void setMethodAccessor(MethodAccessor accessor) {
562 methodAccessor = accessor;
563 // Propagate up
564 if (root != null) {
565 root.setMethodAccessor(accessor);
566 }
567 }
568
569 /**
570 * Returns the default value for the annotation member represented by
571 * this {@code Method} instance. If the member is of a primitive type,
572 * an instance of the corresponding wrapper type is returned. Returns
573 * null if no default is associated with the member, or if the method
574 * instance does not represent a declared member of an annotation type.
575 *
576 * @return the default value for the annotation member represented
577 * by this {@code Method} instance.
578 * @throws TypeNotPresentException if the annotation is of type
579 * {@link Class} and no definition can be found for the
580 * default class value.
581 * @since 1.5
582 */
583 public Object getDefaultValue() {
584 if (annotationDefault == null)
585 return null;
586 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
587 getReturnType());
588 Object result = AnnotationParser.parseMemberValue(
589 memberType, ByteBuffer.wrap(annotationDefault),
590 sun.misc.SharedSecrets.getJavaLangAccess().
591 getConstantPool(getDeclaringClass()),
592 getDeclaringClass());
593 if (result instanceof sun.reflect.annotation.ExceptionProxy)
594 throw new AnnotationFormatError("Invalid default: " + this);
595 return result;
596 }
597
598 /**
599 * {@inheritDoc}
600 * @throws NullPointerException {@inheritDoc}
601 * @since 1.5
602 */
603 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
604 return super.getAnnotation(annotationClass);
605 }
606
607 /**
608 * {@inheritDoc}
609 * @since 1.5
610 */
611 public Annotation[] getDeclaredAnnotations() {
612 return super.getDeclaredAnnotations();
613 }
614
615 /**
616 * {@inheritDoc}
617 * @since 1.5
618 */
619 @Override
620 public Annotation[][] getParameterAnnotations() {
621 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
622 }
623
624 @Override
625 void handleParameterNumberMismatch(int resultLength, int numParameters) {
626 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
627 }
628 }