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 * @jls 9.4 Method Declarations
360 * @jls 9.6.1 Annotation Type Elements
361 */
362 public String toString() {
363 return sharedToString(Modifier.methodModifiers(),
364 isDefault(),
365 parameterTypes,
366 exceptionTypes);
367 }
368
369 @Override
370 void specificToStringHeader(StringBuilder sb) {
371 sb.append(getReturnType().getTypeName()).append(' ');
372 sb.append(getDeclaringClass().getTypeName()).append('.');
373 sb.append(getName());
374 }
375
376 /**
377 * Returns a string describing this {@code Method}, including
378 * type parameters. The string is formatted as the method access
379 * modifiers, if any, followed by an angle-bracketed
380 * comma-separated list of the method's type parameters, if any,
381 * followed by the method's generic return type, followed by a
382 * space, followed by the class declaring the method, followed by
383 * a period, followed by the method name, followed by a
384 * parenthesized, comma-separated list of the method's generic
385 * formal parameter types.
386 *
387 * If this method was declared to take a variable number of
388 * arguments, instead of denoting the last parameter as
389 * "<tt><i>Type</i>[]</tt>", it is denoted as
390 * "<tt><i>Type</i>...</tt>".
391 *
392 * A space is used to separate access modifiers from one another
393 * and from the type parameters or return type. If there are no
394 * type parameters, the type parameter list is elided; if the type
395 * parameter list is present, a space separates the list from the
396 * class name. If the method is declared to throw exceptions, the
397 * parameter list is followed by a space, followed by the word
398 * throws followed by a comma-separated list of the generic thrown
399 * exception types.
400 *
401 * <p>The access modifiers are placed in canonical order as
402 * specified by "The Java Language Specification". This is
403 * {@code public}, {@code protected} or {@code private} first,
404 * and then other modifiers in the following order:
405 * {@code abstract}, {@code default}, {@code static}, {@code final},
406 * {@code synchronized}, {@code native}, {@code strictfp}.
407 *
408 * @return a string describing this {@code Method},
409 * include type parameters
410 *
411 * @since 1.5
412 *
413 * @jls 8.4.3 Method Modifiers
414 * @jls 9.4 Method Declarations
415 * @jls 9.6.1 Annotation Type Elements
416 */
417 @Override
418 public String toGenericString() {
419 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
420 }
421
422 @Override
423 void specificToGenericStringHeader(StringBuilder sb) {
424 Type genRetType = getGenericReturnType();
425 sb.append(genRetType.getTypeName()).append(' ');
426 sb.append(getDeclaringClass().getTypeName()).append('.');
427 sb.append(getName());
428 }
429
430 /**
431 * Invokes the underlying method represented by this {@code Method}
432 * object, on the specified object with the specified parameters.
433 * Individual parameters are automatically unwrapped to match
434 * primitive formal parameters, and both primitive and reference
435 * parameters are subject to method invocation conversions as
436 * necessary.
437 *
438 * <p>If the underlying method is static, then the specified {@code obj}
439 * argument is ignored. It may be null.
440 *
441 * <p>If the number of formal parameters required by the underlying method is
442 * 0, the supplied {@code args} array may be of length 0 or null.
443 *
444 * <p>If the underlying method is an instance method, it is invoked
445 * using dynamic method lookup as documented in The Java Language
446 * Specification, Second Edition, section 15.12.4.4; in particular,
447 * overriding based on the runtime type of the target object will occur.
448 *
449 * <p>If the underlying method is static, the class that declared
450 * the method is initialized if it has not already been initialized.
451 *
452 * <p>If the method completes normally, the value it returns is
453 * returned to the caller of invoke; if the value has a primitive
454 * type, it is first appropriately wrapped in an object. However,
455 * if the value has the type of an array of a primitive type, the
456 * elements of the array are <i>not</i> wrapped in objects; in
457 * other words, an array of primitive type is returned. If the
458 * underlying method return type is void, the invocation returns
459 * null.
460 *
461 * @param obj the object the underlying method is invoked from
462 * @param args the arguments used for the method call
463 * @return the result of dispatching the method represented by
464 * this object on {@code obj} with parameters
465 * {@code args}
466 *
467 * @exception IllegalAccessException if this {@code Method} object
468 * is enforcing Java language access control and the underlying
469 * method is inaccessible.
470 * @exception IllegalArgumentException if the method is an
471 * instance method and the specified object argument
472 * is not an instance of the class or interface
473 * declaring the underlying method (or of a subclass
474 * or implementor thereof); if the number of actual
475 * and formal parameters differ; if an unwrapping
476 * conversion for primitive arguments fails; or if,
477 * after possible unwrapping, a parameter value
478 * cannot be converted to the corresponding formal
479 * parameter type by a method invocation conversion.
480 * @exception InvocationTargetException if the underlying method
481 * throws an exception.
482 * @exception NullPointerException if the specified object is null
483 * and the method is an instance method.
484 * @exception ExceptionInInitializerError if the initialization
485 * provoked by this method fails.
486 */
487 @CallerSensitive
488 public Object invoke(Object obj, Object... args)
489 throws IllegalAccessException, IllegalArgumentException,
490 InvocationTargetException
491 {
492 if (!override) {
493 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
494 Class<?> caller = Reflection.getCallerClass();
495 checkAccess(caller, clazz, obj, modifiers);
496 }
497 }
498 MethodAccessor ma = methodAccessor; // read volatile
499 if (ma == null) {
500 ma = acquireMethodAccessor();
501 }
502 return ma.invoke(obj, args);
503 }
504
505 /**
506 * Returns {@code true} if this method is a bridge
507 * method; returns {@code false} otherwise.
508 *
509 * @return true if and only if this method is a bridge
510 * method as defined by the Java Language Specification.
511 * @since 1.5
512 */
513 public boolean isBridge() {
514 return (getModifiers() & Modifier.BRIDGE) != 0;
515 }
516
517 /**
518 * {@inheritDoc}
519 * @since 1.5
520 */
521 @Override
522 public boolean isVarArgs() {
523 return super.isVarArgs();
524 }
525
526 /**
527 * {@inheritDoc}
528 * @jls 13.1 The Form of a Binary
529 * @since 1.5
530 */
531 @Override
532 public boolean isSynthetic() {
533 return super.isSynthetic();
534 }
535
536 /**
537 * Returns {@code true} if this method is a default
538 * method; returns {@code false} otherwise.
539 *
540 * A default method is a public non-abstract instance method, that
541 * is, a non-static method with a body, declared in an interface
542 * type.
543 *
544 * @return true if and only if this method is a default
545 * method as defined by the Java Language Specification.
546 * @since 1.8
547 */
548 public boolean isDefault() {
549 // Default methods are public non-abstract instance methods
550 // declared in an interface.
551 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
552 Modifier.PUBLIC) && getDeclaringClass().isInterface();
553 }
554
555 // NOTE that there is no synchronization used here. It is correct
556 // (though not efficient) to generate more than one MethodAccessor
557 // for a given Method. However, avoiding synchronization will
558 // probably make the implementation more scalable.
559 private MethodAccessor acquireMethodAccessor() {
560 // First check to see if one has been created yet, and take it
561 // if so
562 MethodAccessor tmp = null;
563 if (root != null) tmp = root.getMethodAccessor();
564 if (tmp != null) {
565 methodAccessor = tmp;
566 } else {
567 // Otherwise fabricate one and propagate it up to the root
568 tmp = reflectionFactory.newMethodAccessor(this);
569 setMethodAccessor(tmp);
570 }
571
572 return tmp;
573 }
574
575 // Returns MethodAccessor for this Method object, not looking up
576 // the chain to the root
577 MethodAccessor getMethodAccessor() {
578 return methodAccessor;
579 }
580
581 // Sets the MethodAccessor for this Method object and
582 // (recursively) its root
583 void setMethodAccessor(MethodAccessor accessor) {
584 methodAccessor = accessor;
585 // Propagate up
586 if (root != null) {
587 root.setMethodAccessor(accessor);
588 }
589 }
590
591 /**
592 * Returns the default value for the annotation member represented by
593 * this {@code Method} instance. If the member is of a primitive type,
594 * an instance of the corresponding wrapper type is returned. Returns
595 * null if no default is associated with the member, or if the method
596 * instance does not represent a declared member of an annotation type.
597 *
598 * @return the default value for the annotation member represented
599 * by this {@code Method} instance.
600 * @throws TypeNotPresentException if the annotation is of type
601 * {@link Class} and no definition can be found for the
602 * default class value.
603 * @since 1.5
604 */
605 public Object getDefaultValue() {
606 if (annotationDefault == null)
607 return null;
608 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
609 getReturnType());
610 Object result = AnnotationParser.parseMemberValue(
611 memberType, ByteBuffer.wrap(annotationDefault),
612 sun.misc.SharedSecrets.getJavaLangAccess().
613 getConstantPool(getDeclaringClass()),
614 getDeclaringClass());
615 if (result instanceof sun.reflect.annotation.ExceptionProxy)
616 throw new AnnotationFormatError("Invalid default: " + this);
617 return result;
618 }
619
620 /**
621 * {@inheritDoc}
622 * @throws NullPointerException {@inheritDoc}
623 * @since 1.5
624 */
625 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
626 return super.getAnnotation(annotationClass);
627 }
628
629 /**
630 * {@inheritDoc}
631 * @since 1.5
632 */
633 public Annotation[] getDeclaredAnnotations() {
634 return super.getDeclaredAnnotations();
635 }
636
637 /**
638 * {@inheritDoc}
639 * @since 1.5
640 */
641 @Override
642 public Annotation[][] getParameterAnnotations() {
643 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
644 }
645
646 /**
647 * {@inheritDoc}
648 * @since 1.8
649 */
650 @Override
651 public AnnotatedType getAnnotatedReturnType() {
652 return getAnnotatedReturnType0(getGenericReturnType());
653 }
654
655 @Override
656 void handleParameterNumberMismatch(int resultLength, int numParameters) {
657 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
658 }
659 }