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
41 /**
42 * A {@code Method} provides information about, and access to, a single method
43 * on a class or interface. The reflected method may be a class method
44 * or an instance method (including an abstract method).
45 *
46 * <p>A {@code Method} permits widening conversions to occur when matching the
47 * actual parameters to invoke with the underlying method's formal
48 * parameters, but it throws an {@code IllegalArgumentException} if a
49 * narrowing conversion would occur.
50 *
51 * @see Member
52 * @see java.lang.Class
53 * @see java.lang.Class#getMethods()
54 * @see java.lang.Class#getMethod(String, Class[])
55 * @see java.lang.Class#getDeclaredMethods()
56 * @see java.lang.Class#getDeclaredMethod(String, Class[])
57 *
58 * @author Kenneth Russell
59 * @author Nakul Saraiya
60 */
61 public final class Method extends Executable {
62 private Class<?> clazz;
63 private int slot;
64 // This is guaranteed to be interned by the VM in the 1.4
65 // reflection implementation
66 private String name;
67 private Class<?> returnType;
68 private Class<?>[] parameterTypes;
69 private Class<?>[] exceptionTypes;
70 private int modifiers;
71 // Generics and annotations support
72 private transient String signature;
73 // generic info repository; lazily initialized
74 private transient MethodRepository genericInfo;
75 private byte[] annotations;
76 private byte[] parameterAnnotations;
77 private byte[] annotationDefault;
78 private volatile MethodAccessor methodAccessor;
79 // For sharing of MethodAccessors. This branching structure is
80 // currently only two levels deep (i.e., one root Method and
81 // potentially many Method objects pointing to it.)
82 private Method root;
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 @SuppressWarnings({"rawtypes", "unchecked"})
198 public TypeVariable<Method>[] getTypeParameters() {
199 if (getGenericSignature() != null)
200 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
201 else
202 return (TypeVariable<Method>[])new TypeVariable[0];
203 }
204
205 /**
206 * Returns a {@code Class} object that represents the formal return type
207 * of the method represented by this {@code Method} object.
208 *
209 * @return the return type for the method this object represents
210 */
211 public Class<?> getReturnType() {
212 return returnType;
213 }
214
215 /**
216 * Returns a {@code Type} object that represents the formal return
217 * type of the method represented by this {@code Method} object.
218 *
219 * <p>If the return type is a parameterized type,
220 * the {@code Type} object returned must accurately reflect
221 * the actual type parameters used in the source code.
222 *
223 * <p>If the return type is a type variable or a parameterized type, it
224 * is created. Otherwise, it is resolved.
225 *
226 * @return a {@code Type} object that represents the formal return
227 * type of the underlying method
228 * @throws GenericSignatureFormatError
229 * if the generic method signature does not conform to the format
230 * specified in
231 * <cite>The Java™ Virtual Machine Specification</cite>
232 * @throws TypeNotPresentException if the underlying method's
233 * return type refers to a non-existent type declaration
234 * @throws MalformedParameterizedTypeException if the
235 * underlying method's return typed refers to a parameterized
236 * type that cannot be instantiated for any reason
237 * @since 1.5
238 */
239 public Type getGenericReturnType() {
240 if (getGenericSignature() != null) {
241 return getGenericInfo().getReturnType();
242 } else { return getReturnType();}
243 }
244
245 /**
246 * {@inheritDoc}
247 */
248 @Override
249 public Class<?>[] getParameterTypes() {
250 return parameterTypes.clone();
251 }
252
253 /**
254 * {@inheritDoc}
255 * @since 1.8
256 */
257 public int getParameterCount() { return parameterTypes.length; }
258
259
260 /**
261 * {@inheritDoc}
262 * @throws GenericSignatureFormatError {@inheritDoc}
263 * @throws TypeNotPresentException {@inheritDoc}
264 * @throws MalformedParameterizedTypeException {@inheritDoc}
265 * @since 1.5
266 */
267 @Override
268 public Type[] getGenericParameterTypes() {
269 return super.getGenericParameterTypes();
270 }
271
272 /**
273 * {@inheritDoc}
274 */
275 @Override
276 public Class<?>[] getExceptionTypes() {
277 return exceptionTypes.clone();
278 }
279
280 /**
281 * {@inheritDoc}
282 * @throws GenericSignatureFormatError {@inheritDoc}
283 * @throws TypeNotPresentException {@inheritDoc}
284 * @throws MalformedParameterizedTypeException {@inheritDoc}
285 * @since 1.5
286 */
287 @Override
288 public Type[] getGenericExceptionTypes() {
289 return super.getGenericExceptionTypes();
290 }
291
292 /**
293 * Compares this {@code Method} against the specified object. Returns
294 * true if the objects are the same. Two {@code Methods} are the same if
295 * they were declared by the same class and have the same name
296 * and formal parameter types and return type.
297 */
298 public boolean equals(Object obj) {
299 if (obj != null && obj instanceof Method) {
300 Method other = (Method)obj;
301 if ((getDeclaringClass() == other.getDeclaringClass())
302 && (getName() == other.getName())) {
303 if (!returnType.equals(other.getReturnType()))
304 return false;
305 return equalParamTypes(parameterTypes, other.parameterTypes);
306 }
307 }
308 return false;
309 }
310
311 /**
312 * Returns a hashcode for this {@code Method}. The hashcode is computed
313 * as the exclusive-or of the hashcodes for the underlying
314 * method's declaring class name and the method's name.
315 */
316 public int hashCode() {
317 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
318 }
319
320 /**
321 * Returns a string describing this {@code Method}. The string is
322 * formatted as the method access modifiers, if any, followed by
323 * the method return type, followed by a space, followed by the
324 * class declaring the method, followed by a period, followed by
325 * the method name, followed by a parenthesized, comma-separated
326 * list of the method's formal parameter types. If the method
327 * throws checked exceptions, the parameter list is followed by a
328 * space, followed by the word throws followed by a
329 * comma-separated list of the thrown exception types.
330 * For example:
331 * <pre>
332 * public boolean java.lang.Object.equals(java.lang.Object)
333 * </pre>
334 *
335 * <p>The access modifiers are placed in canonical order as
336 * specified by "The Java Language Specification". This is
337 * {@code public}, {@code protected} or {@code private} first,
338 * and then other modifiers in the following order:
339 * {@code abstract}, {@code default}, {@code static}, {@code final},
340 * {@code synchronized}, {@code native}, {@code strictfp}.
341 *
342 * @return a string describing this {@code Method}
343 *
344 * @jls 8.4.3 Method Modifiers
345 */
346 public String toString() {
347 return sharedToString(Modifier.methodModifiers(),
348 isDefault(),
349 parameterTypes,
350 exceptionTypes);
351 }
352
353 @Override
354 void specificToStringHeader(StringBuilder sb) {
355 sb.append(getReturnType().getTypeName()).append(' ');
356 sb.append(getDeclaringClass().getTypeName()).append('.');
357 sb.append(getName());
358 }
359
360 /**
361 * Returns a string describing this {@code Method}, including
362 * type parameters. The string is formatted as the method access
363 * modifiers, if any, followed by an angle-bracketed
364 * comma-separated list of the method's type parameters, if any,
365 * followed by the method's generic return type, followed by a
366 * space, followed by the class declaring the method, followed by
367 * a period, followed by the method name, followed by a
368 * parenthesized, comma-separated list of the method's generic
369 * formal parameter types.
370 *
371 * If this method was declared to take a variable number of
372 * arguments, instead of denoting the last parameter as
373 * "<tt><i>Type</i>[]</tt>", it is denoted as
374 * "<tt><i>Type</i>...</tt>".
375 *
376 * A space is used to separate access modifiers from one another
377 * and from the type parameters or return type. If there are no
378 * type parameters, the type parameter list is elided; if the type
379 * parameter list is present, a space separates the list from the
380 * class name. If the method is declared to throw exceptions, the
381 * parameter list is followed by a space, followed by the word
382 * throws followed by a comma-separated list of the generic thrown
383 * exception types.
384 *
385 * <p>The access modifiers are placed in canonical order as
386 * specified by "The Java Language Specification". This is
387 * {@code public}, {@code protected} or {@code private} first,
388 * and then other modifiers in the following order:
389 * {@code abstract}, {@code default}, {@code static}, {@code final},
390 * {@code synchronized}, {@code native}, {@code strictfp}.
391 *
392 * @return a string describing this {@code Method},
393 * include type parameters
394 *
395 * @since 1.5
396 *
397 * @jls 8.4.3 Method Modifiers
398 */
399 @Override
400 public String toGenericString() {
401 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
402 }
403
404 @Override
405 void specificToGenericStringHeader(StringBuilder sb) {
406 Type genRetType = getGenericReturnType();
407 sb.append(genRetType.getTypeName()).append(' ');
408 sb.append(getDeclaringClass().getTypeName()).append('.');
409 sb.append(getName());
410 }
411
412 /**
413 * Invokes the underlying method represented by this {@code Method}
414 * object, on the specified object with the specified parameters.
415 * Individual parameters are automatically unwrapped to match
416 * primitive formal parameters, and both primitive and reference
417 * parameters are subject to method invocation conversions as
418 * necessary.
419 *
420 * <p>If the underlying method is static, then the specified {@code obj}
421 * argument is ignored. It may be null.
422 *
423 * <p>If the number of formal parameters required by the underlying method is
424 * 0, the supplied {@code args} array may be of length 0 or null.
425 *
426 * <p>If the underlying method is an instance method, it is invoked
427 * using dynamic method lookup as documented in The Java Language
428 * Specification, Second Edition, section 15.12.4.4; in particular,
429 * overriding based on the runtime type of the target object will occur.
430 *
431 * <p>If the underlying method is static, the class that declared
432 * the method is initialized if it has not already been initialized.
433 *
434 * <p>If the method completes normally, the value it returns is
435 * returned to the caller of invoke; if the value has a primitive
436 * type, it is first appropriately wrapped in an object. However,
437 * if the value has the type of an array of a primitive type, the
438 * elements of the array are <i>not</i> wrapped in objects; in
439 * other words, an array of primitive type is returned. If the
440 * underlying method return type is void, the invocation returns
441 * null.
442 *
443 * @param obj the object the underlying method is invoked from
444 * @param args the arguments used for the method call
445 * @return the result of dispatching the method represented by
446 * this object on {@code obj} with parameters
447 * {@code args}
448 *
449 * @exception IllegalAccessException if this {@code Method} object
450 * is enforcing Java language access control and the underlying
451 * method is inaccessible.
452 * @exception IllegalArgumentException if the method is an
453 * instance method and the specified object argument
454 * is not an instance of the class or interface
455 * declaring the underlying method (or of a subclass
456 * or implementor thereof); if the number of actual
457 * and formal parameters differ; if an unwrapping
458 * conversion for primitive arguments fails; or if,
459 * after possible unwrapping, a parameter value
460 * cannot be converted to the corresponding formal
461 * parameter type by a method invocation conversion.
462 * @exception InvocationTargetException if the underlying method
463 * throws an exception.
464 * @exception NullPointerException if the specified object is null
465 * and the method is an instance method.
466 * @exception ExceptionInInitializerError if the initialization
467 * provoked by this method fails.
468 */
469 @CallerSensitive
470 public Object invoke(Object obj, Object... args)
471 throws IllegalAccessException, IllegalArgumentException,
472 InvocationTargetException
473 {
474 if (!override) {
475 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
476 Class<?> caller = Reflection.getCallerClass();
477 checkAccess(caller, clazz, obj, modifiers);
478 }
479 }
480 MethodAccessor ma = methodAccessor; // read volatile
481 if (ma == null) {
482 ma = acquireMethodAccessor();
483 }
484 return ma.invoke(obj, args);
485 }
486
487 /**
488 * Returns {@code true} if this method is a bridge
489 * method; returns {@code false} otherwise.
490 *
491 * @return true if and only if this method is a bridge
492 * method as defined by the Java Language Specification.
493 * @since 1.5
494 */
495 public boolean isBridge() {
496 return (getModifiers() & Modifier.BRIDGE) != 0;
497 }
498
499 /**
500 * {@inheritDoc}
501 * @since 1.5
502 */
503 @Override
504 public boolean isVarArgs() {
505 return super.isVarArgs();
506 }
507
508 /**
509 * {@inheritDoc}
510 * @jls 13.1 The Form of a Binary
511 * @since 1.5
512 */
513 @Override
514 public boolean isSynthetic() {
515 return super.isSynthetic();
516 }
517
518 /**
519 * Returns {@code true} if this method is a default
520 * method; returns {@code false} otherwise.
521 *
522 * A default method is a public non-abstract instance method, that
523 * is, a non-static method with a body, declared in an interface
524 * type.
525 *
526 * @return true if and only if this method is a default
527 * method as defined by the Java Language Specification.
528 * @since 1.8
529 */
530 public boolean isDefault() {
531 // Default methods are public non-abstract instance methods
532 // declared in an interface.
533 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
534 Modifier.PUBLIC) && getDeclaringClass().isInterface();
535 }
536
537 // NOTE that there is no synchronization used here. It is correct
538 // (though not efficient) to generate more than one MethodAccessor
539 // for a given Method. However, avoiding synchronization will
540 // probably make the implementation more scalable.
541 private MethodAccessor acquireMethodAccessor() {
542 // First check to see if one has been created yet, and take it
543 // if so
544 MethodAccessor tmp = null;
545 if (root != null) tmp = root.getMethodAccessor();
546 if (tmp != null) {
547 methodAccessor = tmp;
548 } else {
549 // Otherwise fabricate one and propagate it up to the root
550 tmp = reflectionFactory.newMethodAccessor(this);
551 setMethodAccessor(tmp);
552 }
553
554 return tmp;
555 }
556
557 // Returns MethodAccessor for this Method object, not looking up
558 // the chain to the root
559 MethodAccessor getMethodAccessor() {
560 return methodAccessor;
561 }
562
563 // Sets the MethodAccessor for this Method object and
564 // (recursively) its root
565 void setMethodAccessor(MethodAccessor accessor) {
566 methodAccessor = accessor;
567 // Propagate up
568 if (root != null) {
569 root.setMethodAccessor(accessor);
570 }
571 }
572
573 /**
574 * Returns the default value for the annotation member represented by
575 * this {@code Method} instance. If the member is of a primitive type,
576 * an instance of the corresponding wrapper type is returned. Returns
577 * null if no default is associated with the member, or if the method
578 * instance does not represent a declared member of an annotation type.
579 *
580 * @return the default value for the annotation member represented
581 * by this {@code Method} instance.
582 * @throws TypeNotPresentException if the annotation is of type
583 * {@link Class} and no definition can be found for the
584 * default class value.
585 * @since 1.5
586 */
587 public Object getDefaultValue() {
588 if (annotationDefault == null)
589 return null;
590 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
591 getReturnType());
592 Object result = AnnotationParser.parseMemberValue(
593 memberType, ByteBuffer.wrap(annotationDefault),
594 sun.misc.SharedSecrets.getJavaLangAccess().
595 getConstantPool(getDeclaringClass()),
596 getDeclaringClass());
597 if (result instanceof sun.reflect.annotation.ExceptionProxy)
598 throw new AnnotationFormatError("Invalid default: " + this);
599 return result;
600 }
601
602 /**
603 * {@inheritDoc}
604 * @throws NullPointerException {@inheritDoc}
605 * @since 1.5
606 */
607 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
608 return super.getAnnotation(annotationClass);
609 }
610
611 /**
612 * {@inheritDoc}
613 * @since 1.5
614 */
615 public Annotation[] getDeclaredAnnotations() {
616 return super.getDeclaredAnnotations();
617 }
618
619 /**
620 * {@inheritDoc}
621 * @since 1.5
622 */
623 @Override
624 public Annotation[][] getParameterAnnotations() {
625 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
626 }
627
628 /**
629 * {@inheritDoc}
630 * @since 1.8
631 */
632 @Override
633 public AnnotatedType getAnnotatedReturnType() {
634 return getAnnotatedReturnType0(getGenericReturnType());
635 }
636
637 @Override
638 void handleParameterNumberMismatch(int resultLength, int numParameters) {
639 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
640 }
641 }