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 //
83 // If this branching structure would ever contain cycles, deadlocks can
84 // occur in annotation code.
85 private Method root;
86
87 // Generics infrastructure
88 private String getGenericSignature() {return signature;}
89
90 // Accessor for factory
91 private GenericsFactory getFactory() {
92 // create scope and factory
93 return CoreReflectionFactory.make(this, MethodScope.make(this));
94 }
95
96 // Accessor for generic info repository
97 @Override
98 MethodRepository getGenericInfo() {
99 // lazily initialize repository if necessary
100 if (genericInfo == null) {
101 // create and cache generic info repository
102 genericInfo = MethodRepository.make(getGenericSignature(),
103 getFactory());
104 }
105 return genericInfo; //return cached repository
106 }
107
108 /**
109 * Package-private constructor used by ReflectAccess to enable
110 * instantiation of these objects in Java code from the java.lang
111 * package via sun.reflect.LangReflectAccess.
112 */
113 Method(Class<?> declaringClass,
114 String name,
115 Class<?>[] parameterTypes,
116 Class<?> returnType,
117 Class<?>[] checkedExceptions,
118 int modifiers,
119 int slot,
120 String signature,
121 byte[] annotations,
122 byte[] parameterAnnotations,
123 byte[] annotationDefault) {
124 this.clazz = declaringClass;
125 this.name = name;
126 this.parameterTypes = parameterTypes;
127 this.returnType = returnType;
128 this.exceptionTypes = checkedExceptions;
129 this.modifiers = modifiers;
130 this.slot = slot;
131 this.signature = signature;
132 this.annotations = annotations;
133 this.parameterAnnotations = parameterAnnotations;
134 this.annotationDefault = annotationDefault;
135 }
136
137 /**
138 * Package-private routine (exposed to java.lang.Class via
139 * ReflectAccess) which returns a copy of this Method. The copy's
140 * "root" field points to this Method.
141 */
142 Method copy() {
143 // This routine enables sharing of MethodAccessor objects
144 // among Method objects which refer to the same underlying
145 // method in the VM. (All of this contortion is only necessary
146 // because of the "accessibility" bit in AccessibleObject,
147 // which implicitly requires that new java.lang.reflect
148 // objects be fabricated for each reflective call on Class
149 // objects.)
150 if (this.root != null)
151 throw new IllegalArgumentException("Can not copy a non-root Method");
152
153 Method res = new Method(clazz, name, parameterTypes, returnType,
154 exceptionTypes, modifiers, slot, signature,
155 annotations, parameterAnnotations, annotationDefault);
156 res.root = this;
157 // Might as well eagerly propagate this if already present
158 res.methodAccessor = methodAccessor;
159 return res;
160 }
161
162 /**
163 * Used by Excecutable for annotation sharing.
164 */
165 @Override
166 Executable getRoot() {
167 return root;
168 }
169
170 @Override
171 boolean hasGenericInformation() {
172 return (getGenericSignature() != null);
173 }
174
175 @Override
176 byte[] getAnnotationBytes() {
177 return annotations;
178 }
179
180 /**
181 * {@inheritDoc}
182 */
183 @Override
184 public Class<?> getDeclaringClass() {
185 return clazz;
186 }
187
188 /**
189 * Returns the name of the method represented by this {@code Method}
190 * object, as a {@code String}.
191 */
192 @Override
193 public String getName() {
194 return name;
195 }
196
197 /**
198 * {@inheritDoc}
199 */
200 @Override
201 public int getModifiers() {
202 return modifiers;
203 }
204
205 /**
206 * {@inheritDoc}
207 * @throws GenericSignatureFormatError {@inheritDoc}
208 * @since 1.5
209 */
210 @Override
211 @SuppressWarnings({"rawtypes", "unchecked"})
212 public TypeVariable<Method>[] getTypeParameters() {
213 if (getGenericSignature() != null)
214 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
215 else
216 return (TypeVariable<Method>[])new TypeVariable[0];
217 }
218
219 /**
220 * Returns a {@code Class} object that represents the formal return type
221 * of the method represented by this {@code Method} object.
222 *
223 * @return the return type for the method this object represents
224 */
225 public Class<?> getReturnType() {
226 return returnType;
227 }
228
229 /**
230 * Returns a {@code Type} object that represents the formal return
231 * type of the method represented by this {@code Method} object.
232 *
233 * <p>If the return type is a parameterized type,
234 * the {@code Type} object returned must accurately reflect
235 * the actual type parameters used in the source code.
236 *
237 * <p>If the return type is a type variable or a parameterized type, it
238 * is created. Otherwise, it is resolved.
239 *
240 * @return a {@code Type} object that represents the formal return
241 * type of the underlying method
242 * @throws GenericSignatureFormatError
243 * if the generic method signature does not conform to the format
244 * specified in
245 * <cite>The Java™ Virtual Machine Specification</cite>
246 * @throws TypeNotPresentException if the underlying method's
247 * return type refers to a non-existent type declaration
248 * @throws MalformedParameterizedTypeException if the
249 * underlying method's return typed refers to a parameterized
250 * type that cannot be instantiated for any reason
251 * @since 1.5
252 */
253 public Type getGenericReturnType() {
254 if (getGenericSignature() != null) {
255 return getGenericInfo().getReturnType();
256 } else { return getReturnType();}
257 }
258
259 /**
260 * {@inheritDoc}
261 */
262 @Override
263 public Class<?>[] getParameterTypes() {
264 return parameterTypes.clone();
265 }
266
267 /**
268 * {@inheritDoc}
269 * @since 1.8
270 */
271 public int getParameterCount() { return parameterTypes.length; }
272
273
274 /**
275 * {@inheritDoc}
276 * @throws GenericSignatureFormatError {@inheritDoc}
277 * @throws TypeNotPresentException {@inheritDoc}
278 * @throws MalformedParameterizedTypeException {@inheritDoc}
279 * @since 1.5
280 */
281 @Override
282 public Type[] getGenericParameterTypes() {
283 return super.getGenericParameterTypes();
284 }
285
286 /**
287 * {@inheritDoc}
288 */
289 @Override
290 public Class<?>[] getExceptionTypes() {
291 return exceptionTypes.clone();
292 }
293
294 /**
295 * {@inheritDoc}
296 * @throws GenericSignatureFormatError {@inheritDoc}
297 * @throws TypeNotPresentException {@inheritDoc}
298 * @throws MalformedParameterizedTypeException {@inheritDoc}
299 * @since 1.5
300 */
301 @Override
302 public Type[] getGenericExceptionTypes() {
303 return super.getGenericExceptionTypes();
304 }
305
306 /**
307 * Compares this {@code Method} against the specified object. Returns
308 * true if the objects are the same. Two {@code Methods} are the same if
309 * they were declared by the same class and have the same name
310 * and formal parameter types and return type.
311 */
312 public boolean equals(Object obj) {
313 if (obj != null && obj instanceof Method) {
314 Method other = (Method)obj;
315 if ((getDeclaringClass() == other.getDeclaringClass())
316 && (getName() == other.getName())) {
317 if (!returnType.equals(other.getReturnType()))
318 return false;
319 return equalParamTypes(parameterTypes, other.parameterTypes);
320 }
321 }
322 return false;
323 }
324
325 /**
326 * Returns a hashcode for this {@code Method}. The hashcode is computed
327 * as the exclusive-or of the hashcodes for the underlying
328 * method's declaring class name and the method's name.
329 */
330 public int hashCode() {
331 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
332 }
333
334 /**
335 * Returns a string describing this {@code Method}. The string is
336 * formatted as the method access modifiers, if any, followed by
337 * the method return type, followed by a space, followed by the
338 * class declaring the method, followed by a period, followed by
339 * the method name, followed by a parenthesized, comma-separated
340 * list of the method's formal parameter types. If the method
341 * throws checked exceptions, the parameter list is followed by a
342 * space, followed by the word throws followed by a
343 * comma-separated list of the thrown exception types.
344 * For example:
345 * <pre>
346 * public boolean java.lang.Object.equals(java.lang.Object)
347 * </pre>
348 *
349 * <p>The access modifiers are placed in canonical order as
350 * specified by "The Java Language Specification". This is
351 * {@code public}, {@code protected} or {@code private} first,
352 * and then other modifiers in the following order:
353 * {@code abstract}, {@code default}, {@code static}, {@code final},
354 * {@code synchronized}, {@code native}, {@code strictfp}.
355 *
356 * @return a string describing this {@code Method}
357 *
358 * @jls 8.4.3 Method Modifiers
359 */
360 public String toString() {
361 return sharedToString(Modifier.methodModifiers(),
362 isDefault(),
363 parameterTypes,
364 exceptionTypes);
365 }
366
367 @Override
368 void specificToStringHeader(StringBuilder sb) {
369 sb.append(getReturnType().getTypeName()).append(' ');
370 sb.append(getDeclaringClass().getTypeName()).append('.');
371 sb.append(getName());
372 }
373
374 /**
375 * Returns a string describing this {@code Method}, including
376 * type parameters. The string is formatted as the method access
377 * modifiers, if any, followed by an angle-bracketed
378 * comma-separated list of the method's type parameters, if any,
379 * followed by the method's generic return type, followed by a
380 * space, followed by the class declaring the method, followed by
381 * a period, followed by the method name, followed by a
382 * parenthesized, comma-separated list of the method's generic
383 * formal parameter types.
384 *
385 * If this method was declared to take a variable number of
386 * arguments, instead of denoting the last parameter as
387 * "<tt><i>Type</i>[]</tt>", it is denoted as
388 * "<tt><i>Type</i>...</tt>".
389 *
390 * A space is used to separate access modifiers from one another
391 * and from the type parameters or return type. If there are no
392 * type parameters, the type parameter list is elided; if the type
393 * parameter list is present, a space separates the list from the
394 * class name. If the method is declared to throw exceptions, the
395 * parameter list is followed by a space, followed by the word
396 * throws followed by a comma-separated list of the generic thrown
397 * exception types.
398 *
399 * <p>The access modifiers are placed in canonical order as
400 * specified by "The Java Language Specification". This is
401 * {@code public}, {@code protected} or {@code private} first,
402 * and then other modifiers in the following order:
403 * {@code abstract}, {@code default}, {@code static}, {@code final},
404 * {@code synchronized}, {@code native}, {@code strictfp}.
405 *
406 * @return a string describing this {@code Method},
407 * include type parameters
408 *
409 * @since 1.5
410 *
411 * @jls 8.4.3 Method Modifiers
412 */
413 @Override
414 public String toGenericString() {
415 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
416 }
417
418 @Override
419 void specificToGenericStringHeader(StringBuilder sb) {
420 Type genRetType = getGenericReturnType();
421 sb.append(genRetType.getTypeName()).append(' ');
422 sb.append(getDeclaringClass().getTypeName()).append('.');
423 sb.append(getName());
424 }
425
426 /**
427 * Invokes the underlying method represented by this {@code Method}
428 * object, on the specified object with the specified parameters.
429 * Individual parameters are automatically unwrapped to match
430 * primitive formal parameters, and both primitive and reference
431 * parameters are subject to method invocation conversions as
432 * necessary.
433 *
434 * <p>If the underlying method is static, then the specified {@code obj}
435 * argument is ignored. It may be null.
436 *
437 * <p>If the number of formal parameters required by the underlying method is
438 * 0, the supplied {@code args} array may be of length 0 or null.
439 *
440 * <p>If the underlying method is an instance method, it is invoked
441 * using dynamic method lookup as documented in The Java Language
442 * Specification, Second Edition, section 15.12.4.4; in particular,
443 * overriding based on the runtime type of the target object will occur.
444 *
445 * <p>If the underlying method is static, the class that declared
446 * the method is initialized if it has not already been initialized.
447 *
448 * <p>If the method completes normally, the value it returns is
449 * returned to the caller of invoke; if the value has a primitive
450 * type, it is first appropriately wrapped in an object. However,
451 * if the value has the type of an array of a primitive type, the
452 * elements of the array are <i>not</i> wrapped in objects; in
453 * other words, an array of primitive type is returned. If the
454 * underlying method return type is void, the invocation returns
455 * null.
456 *
457 * @param obj the object the underlying method is invoked from
458 * @param args the arguments used for the method call
459 * @return the result of dispatching the method represented by
460 * this object on {@code obj} with parameters
461 * {@code args}
462 *
463 * @exception IllegalAccessException if this {@code Method} object
464 * is enforcing Java language access control and the underlying
465 * method is inaccessible.
466 * @exception IllegalArgumentException if the method is an
467 * instance method and the specified object argument
468 * is not an instance of the class or interface
469 * declaring the underlying method (or of a subclass
470 * or implementor thereof); if the number of actual
471 * and formal parameters differ; if an unwrapping
472 * conversion for primitive arguments fails; or if,
473 * after possible unwrapping, a parameter value
474 * cannot be converted to the corresponding formal
475 * parameter type by a method invocation conversion.
476 * @exception InvocationTargetException if the underlying method
477 * throws an exception.
478 * @exception NullPointerException if the specified object is null
479 * and the method is an instance method.
480 * @exception ExceptionInInitializerError if the initialization
481 * provoked by this method fails.
482 */
483 @CallerSensitive
484 public Object invoke(Object obj, Object... args)
485 throws IllegalAccessException, IllegalArgumentException,
486 InvocationTargetException
487 {
488 if (!override) {
489 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
490 Class<?> caller = Reflection.getCallerClass();
491 checkAccess(caller, clazz, obj, modifiers);
492 }
493 }
494 MethodAccessor ma = methodAccessor; // read volatile
495 if (ma == null) {
496 ma = acquireMethodAccessor();
497 }
498 return ma.invoke(obj, args);
499 }
500
501 /**
502 * Returns {@code true} if this method is a bridge
503 * method; returns {@code false} otherwise.
504 *
505 * @return true if and only if this method is a bridge
506 * method as defined by the Java Language Specification.
507 * @since 1.5
508 */
509 public boolean isBridge() {
510 return (getModifiers() & Modifier.BRIDGE) != 0;
511 }
512
513 /**
514 * {@inheritDoc}
515 * @since 1.5
516 */
517 @Override
518 public boolean isVarArgs() {
519 return super.isVarArgs();
520 }
521
522 /**
523 * {@inheritDoc}
524 * @jls 13.1 The Form of a Binary
525 * @since 1.5
526 */
527 @Override
528 public boolean isSynthetic() {
529 return super.isSynthetic();
530 }
531
532 /**
533 * Returns {@code true} if this method is a default
534 * method; returns {@code false} otherwise.
535 *
536 * A default method is a public non-abstract instance method, that
537 * is, a non-static method with a body, declared in an interface
538 * type.
539 *
540 * @return true if and only if this method is a default
541 * method as defined by the Java Language Specification.
542 * @since 1.8
543 */
544 public boolean isDefault() {
545 // Default methods are public non-abstract instance methods
546 // declared in an interface.
547 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
548 Modifier.PUBLIC) && getDeclaringClass().isInterface();
549 }
550
551 // NOTE that there is no synchronization used here. It is correct
552 // (though not efficient) to generate more than one MethodAccessor
553 // for a given Method. However, avoiding synchronization will
554 // probably make the implementation more scalable.
555 private MethodAccessor acquireMethodAccessor() {
556 // First check to see if one has been created yet, and take it
557 // if so
558 MethodAccessor tmp = null;
559 if (root != null) tmp = root.getMethodAccessor();
560 if (tmp != null) {
561 methodAccessor = tmp;
562 } else {
563 // Otherwise fabricate one and propagate it up to the root
564 tmp = reflectionFactory.newMethodAccessor(this);
565 setMethodAccessor(tmp);
566 }
567
568 return tmp;
569 }
570
571 // Returns MethodAccessor for this Method object, not looking up
572 // the chain to the root
573 MethodAccessor getMethodAccessor() {
574 return methodAccessor;
575 }
576
577 // Sets the MethodAccessor for this Method object and
578 // (recursively) its root
579 void setMethodAccessor(MethodAccessor accessor) {
580 methodAccessor = accessor;
581 // Propagate up
582 if (root != null) {
583 root.setMethodAccessor(accessor);
584 }
585 }
586
587 /**
588 * Returns the default value for the annotation member represented by
589 * this {@code Method} instance. If the member is of a primitive type,
590 * an instance of the corresponding wrapper type is returned. Returns
591 * null if no default is associated with the member, or if the method
592 * instance does not represent a declared member of an annotation type.
593 *
594 * @return the default value for the annotation member represented
595 * by this {@code Method} instance.
596 * @throws TypeNotPresentException if the annotation is of type
597 * {@link Class} and no definition can be found for the
598 * default class value.
599 * @since 1.5
600 */
601 public Object getDefaultValue() {
602 if (annotationDefault == null)
603 return null;
604 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
605 getReturnType());
606 Object result = AnnotationParser.parseMemberValue(
607 memberType, ByteBuffer.wrap(annotationDefault),
608 sun.misc.SharedSecrets.getJavaLangAccess().
609 getConstantPool(getDeclaringClass()),
610 getDeclaringClass());
611 if (result instanceof sun.reflect.annotation.ExceptionProxy)
612 throw new AnnotationFormatError("Invalid default: " + this);
613 return result;
614 }
615
616 /**
617 * {@inheritDoc}
618 * @throws NullPointerException {@inheritDoc}
619 * @since 1.5
620 */
621 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
622 return super.getAnnotation(annotationClass);
623 }
624
625 /**
626 * {@inheritDoc}
627 * @since 1.5
628 */
629 public Annotation[] getDeclaredAnnotations() {
630 return super.getDeclaredAnnotations();
631 }
632
633 /**
634 * {@inheritDoc}
635 * @since 1.5
636 */
637 @Override
638 public Annotation[][] getParameterAnnotations() {
639 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
640 }
641
642 /**
643 * {@inheritDoc}
644 * @since 1.8
645 */
646 @Override
647 public AnnotatedType getAnnotatedReturnType() {
648 return getAnnotatedReturnType0(getGenericReturnType());
649 }
650
651 @Override
652 void handleParameterNumberMismatch(int resultLength, int numParameters) {
653 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
654 }
655 }