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.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 @Override
169 byte[] getTypeAnnotationBytes() {
170 return typeAnnotations;
171 }
172
173 /**
174 * {@inheritDoc}
175 */
176 @Override
177 public Class<?> getDeclaringClass() {
178 return clazz;
179 }
180
181 /**
182 * Returns the name of the method represented by this {@code Method}
183 * object, as a {@code String}.
184 */
185 @Override
186 public String getName() {
187 return name;
188 }
189
190 /**
191 * {@inheritDoc}
192 */
193 @Override
194 public int getModifiers() {
195 return modifiers;
196 }
197
198 /**
199 * {@inheritDoc}
200 * @throws GenericSignatureFormatError {@inheritDoc}
201 * @since 1.5
202 */
203 @Override
204 @SuppressWarnings({"rawtypes", "unchecked"})
205 public TypeVariable<Method>[] getTypeParameters() {
206 if (getGenericSignature() != null)
207 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
208 else
209 return (TypeVariable<Method>[])new TypeVariable[0];
210 }
211
212 /**
213 * Returns a {@code Class} object that represents the formal return type
214 * of the method represented by this {@code Method} object.
215 *
216 * @return the return type for the method this object represents
217 */
218 public Class<?> getReturnType() {
219 return returnType;
220 }
221
222 /**
223 * Returns a {@code Type} object that represents the formal return
224 * type of the method represented by this {@code Method} object.
225 *
226 * <p>If the return type is a parameterized type,
227 * the {@code Type} object returned must accurately reflect
228 * the actual type parameters used in the source code.
229 *
230 * <p>If the return type is a type variable or a parameterized type, it
231 * is created. Otherwise, it is resolved.
232 *
233 * @return a {@code Type} object that represents the formal return
234 * type of the underlying method
235 * @throws GenericSignatureFormatError
236 * if the generic method signature does not conform to the format
237 * specified in
238 * <cite>The Java™ Virtual Machine Specification</cite>
239 * @throws TypeNotPresentException if the underlying method's
240 * return type refers to a non-existent type declaration
241 * @throws MalformedParameterizedTypeException if the
242 * underlying method's return typed refers to a parameterized
243 * type that cannot be instantiated for any reason
244 * @since 1.5
245 */
246 public Type getGenericReturnType() {
247 if (getGenericSignature() != null) {
248 return getGenericInfo().getReturnType();
249 } else { return getReturnType();}
250 }
251
252 /**
253 * {@inheritDoc}
254 */
255 @Override
256 public Class<?>[] getParameterTypes() {
257 return parameterTypes.clone();
258 }
259
260 /**
261 * {@inheritDoc}
262 */
263 public int getParameterCount() { return parameterTypes.length; }
264
265
266 /**
267 * {@inheritDoc}
268 * @throws GenericSignatureFormatError {@inheritDoc}
269 * @throws TypeNotPresentException {@inheritDoc}
270 * @throws MalformedParameterizedTypeException {@inheritDoc}
271 * @since 1.5
272 */
273 @Override
274 public Type[] getGenericParameterTypes() {
275 return super.getGenericParameterTypes();
276 }
277
278 /**
279 * {@inheritDoc}
280 */
281 @Override
282 public Class<?>[] getExceptionTypes() {
283 return exceptionTypes.clone();
284 }
285
286 /**
287 * {@inheritDoc}
288 * @throws GenericSignatureFormatError {@inheritDoc}
289 * @throws TypeNotPresentException {@inheritDoc}
290 * @throws MalformedParameterizedTypeException {@inheritDoc}
291 * @since 1.5
292 */
293 @Override
294 public Type[] getGenericExceptionTypes() {
295 return super.getGenericExceptionTypes();
296 }
297
298 /**
299 * Compares this {@code Method} against the specified object. Returns
300 * true if the objects are the same. Two {@code Methods} are the same if
301 * they were declared by the same class and have the same name
302 * and formal parameter types and return type.
303 */
304 public boolean equals(Object obj) {
305 if (obj != null && obj instanceof Method) {
306 Method other = (Method)obj;
307 if ((getDeclaringClass() == other.getDeclaringClass())
308 && (getName() == other.getName())) {
309 if (!returnType.equals(other.getReturnType()))
310 return false;
311 return equalParamTypes(parameterTypes, other.parameterTypes);
312 }
313 }
314 return false;
315 }
316
317 /**
318 * Returns a hashcode for this {@code Method}. The hashcode is computed
319 * as the exclusive-or of the hashcodes for the underlying
320 * method's declaring class name and the method's name.
321 */
322 public int hashCode() {
323 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
324 }
325
326 /**
327 * Returns a string describing this {@code Method}. The string is
328 * formatted as the method access modifiers, if any, followed by
329 * the method return type, followed by a space, followed by the
330 * class declaring the method, followed by a period, followed by
331 * the method name, followed by a parenthesized, comma-separated
332 * list of the method's formal parameter types. If the method
333 * throws checked exceptions, the parameter list is followed by a
334 * space, followed by the word throws followed by a
335 * comma-separated list of the thrown exception types.
336 * For example:
337 * <pre>
338 * public boolean java.lang.Object.equals(java.lang.Object)
339 * </pre>
340 *
341 * <p>The access modifiers are placed in canonical order as
342 * specified by "The Java Language Specification". This is
343 * {@code public}, {@code protected} or {@code private} first,
344 * and then other modifiers in the following order:
345 * {@code abstract}, {@code static}, {@code final},
346 * {@code synchronized}, {@code native}, {@code strictfp},
347 * {@code default}.
348 *
349 * @return a string describing this {@code Method}
350 *
351 * @jls 8.4.3 Method Modifiers
352 */
353 public String toString() {
354 return sharedToString(Modifier.methodModifiers(),
355 isDefault(),
356 parameterTypes,
357 exceptionTypes);
358 }
359
360 @Override
361 void specificToStringHeader(StringBuilder sb) {
362 sb.append(Field.getTypeName(getReturnType())).append(' ');
363 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
364 sb.append(getName());
365 }
366
367 /**
368 * Returns a string describing this {@code Method}, including
369 * type parameters. The string is formatted as the method access
370 * modifiers, if any, followed by an angle-bracketed
371 * comma-separated list of the method's type parameters, if any,
372 * followed by the method's generic return type, followed by a
373 * space, followed by the class declaring the method, followed by
374 * a period, followed by the method name, followed by a
375 * parenthesized, comma-separated list of the method's generic
376 * formal parameter types.
377 *
378 * If this method was declared to take a variable number of
379 * arguments, instead of denoting the last parameter as
380 * "<tt><i>Type</i>[]</tt>", it is denoted as
381 * "<tt><i>Type</i>...</tt>".
382 *
383 * A space is used to separate access modifiers from one another
384 * and from the type parameters or return type. If there are no
385 * type parameters, the type parameter list is elided; if the type
386 * parameter list is present, a space separates the list from the
387 * class name. If the method is declared to throw exceptions, the
388 * parameter list is followed by a space, followed by the word
389 * throws followed by a comma-separated list of the generic thrown
390 * exception types. If there are no type parameters, the type
391 * parameter list is elided.
392 *
393 * <p>The access modifiers are placed in canonical order as
394 * specified by "The Java Language Specification". This is
395 * {@code public}, {@code protected} or {@code private} first,
396 * and then other modifiers in the following order:
397 * {@code abstract}, {@code static}, {@code final},
398 * {@code synchronized}, {@code native}, {@code strictfp},
399 * {@code default}.
400 *
401 * @return a string describing this {@code Method},
402 * include type parameters
403 *
404 * @since 1.5
405 *
406 * @jls 8.4.3 Method Modifiers
407 */
408 @Override
409 public String toGenericString() {
410 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
411 }
412
413 @Override
414 void specificToGenericStringHeader(StringBuilder sb) {
415 Type genRetType = getGenericReturnType();
416 sb.append( ((genRetType instanceof Class<?>)?
417 Field.getTypeName((Class<?>)genRetType):genRetType.toString()))
418 .append(' ');
419
420 sb.append(Field.getTypeName(getDeclaringClass())).append('.');
421 sb.append(getName());
422 }
423
424 /**
425 * Invokes the underlying method represented by this {@code Method}
426 * object, on the specified object with the specified parameters.
427 * Individual parameters are automatically unwrapped to match
428 * primitive formal parameters, and both primitive and reference
429 * parameters are subject to method invocation conversions as
430 * necessary.
431 *
432 * <p>If the underlying method is static, then the specified {@code obj}
433 * argument is ignored. It may be null.
434 *
435 * <p>If the number of formal parameters required by the underlying method is
436 * 0, the supplied {@code args} array may be of length 0 or null.
437 *
438 * <p>If the underlying method is an instance method, it is invoked
439 * using dynamic method lookup as documented in The Java Language
440 * Specification, Second Edition, section 15.12.4.4; in particular,
441 * overriding based on the runtime type of the target object will occur.
442 *
443 * <p>If the underlying method is static, the class that declared
444 * the method is initialized if it has not already been initialized.
445 *
446 * <p>If the method completes normally, the value it returns is
447 * returned to the caller of invoke; if the value has a primitive
448 * type, it is first appropriately wrapped in an object. However,
449 * if the value has the type of an array of a primitive type, the
450 * elements of the array are <i>not</i> wrapped in objects; in
451 * other words, an array of primitive type is returned. If the
452 * underlying method return type is void, the invocation returns
453 * null.
454 *
455 * @param obj the object the underlying method is invoked from
456 * @param args the arguments used for the method call
457 * @return the result of dispatching the method represented by
458 * this object on {@code obj} with parameters
459 * {@code args}
460 *
461 * @exception IllegalAccessException if this {@code Method} object
462 * is enforcing Java language access control and the underlying
463 * method is inaccessible.
464 * @exception IllegalArgumentException if the method is an
465 * instance method and the specified object argument
466 * is not an instance of the class or interface
467 * declaring the underlying method (or of a subclass
468 * or implementor thereof); if the number of actual
469 * and formal parameters differ; if an unwrapping
470 * conversion for primitive arguments fails; or if,
471 * after possible unwrapping, a parameter value
472 * cannot be converted to the corresponding formal
473 * parameter type by a method invocation conversion.
474 * @exception InvocationTargetException if the underlying method
475 * throws an exception.
476 * @exception NullPointerException if the specified object is null
477 * and the method is an instance method.
478 * @exception ExceptionInInitializerError if the initialization
479 * provoked by this method fails.
480 */
481 public Object invoke(Object obj, Object... args)
482 throws IllegalAccessException, IllegalArgumentException,
483 InvocationTargetException
484 {
485 if (!override) {
486 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
487 Class<?> caller = Reflection.getCallerClass(1);
488
489 checkAccess(caller, clazz, obj, modifiers);
490 }
491 }
492 MethodAccessor ma = methodAccessor; // read volatile
493 if (ma == null) {
494 ma = acquireMethodAccessor();
495 }
496 return ma.invoke(obj, args);
497 }
498
499 /**
500 * Returns {@code true} if this method is a bridge
501 * method; returns {@code false} otherwise.
502 *
503 * @return true if and only if this method is a bridge
504 * method as defined by the Java Language Specification.
505 * @since 1.5
506 */
507 public boolean isBridge() {
508 return (getModifiers() & Modifier.BRIDGE) != 0;
509 }
510
511 /**
512 * {@inheritDoc}
513 * @since 1.5
514 */
515 @Override
516 public boolean isVarArgs() {
517 return super.isVarArgs();
518 }
519
520 /**
521 * {@inheritDoc}
522 * @jls 13.1 The Form of a Binary
523 * @since 1.5
524 */
525 @Override
526 public boolean isSynthetic() {
527 return super.isSynthetic();
528 }
529
530 /**
531 * Returns {@code true} if this method is a default
532 * method; returns {@code false} otherwise.
533 *
534 * A default method is a public non-abstract instance method, that
535 * is, a non-static method with a body, declared in an interface
536 * type.
537 *
538 * @return true if and only if this method is a default
539 * method as defined by the Java Language Specification.
540 * @since 1.8
541 */
542 public boolean isDefault() {
543 // Default methods are public non-abstract instance methods
544 // declared in an interface.
545 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
546 Modifier.PUBLIC) && getDeclaringClass().isInterface();
547 }
548
549 // NOTE that there is no synchronization used here. It is correct
550 // (though not efficient) to generate more than one MethodAccessor
551 // for a given Method. However, avoiding synchronization will
552 // probably make the implementation more scalable.
553 private MethodAccessor acquireMethodAccessor() {
554 // First check to see if one has been created yet, and take it
555 // if so
556 MethodAccessor tmp = null;
557 if (root != null) tmp = root.getMethodAccessor();
558 if (tmp != null) {
559 methodAccessor = tmp;
560 } else {
561 // Otherwise fabricate one and propagate it up to the root
562 tmp = reflectionFactory.newMethodAccessor(this);
563 setMethodAccessor(tmp);
564 }
565
566 return tmp;
567 }
568
569 // Returns MethodAccessor for this Method object, not looking up
570 // the chain to the root
571 MethodAccessor getMethodAccessor() {
572 return methodAccessor;
573 }
574
575 // Sets the MethodAccessor for this Method object and
576 // (recursively) its root
577 void setMethodAccessor(MethodAccessor accessor) {
578 methodAccessor = accessor;
579 // Propagate up
580 if (root != null) {
581 root.setMethodAccessor(accessor);
582 }
583 }
584
585 /**
586 * Returns the default value for the annotation member represented by
587 * this {@code Method} instance. If the member is of a primitive type,
588 * an instance of the corresponding wrapper type is returned. Returns
589 * null if no default is associated with the member, or if the method
590 * instance does not represent a declared member of an annotation type.
591 *
592 * @return the default value for the annotation member represented
593 * by this {@code Method} instance.
594 * @throws TypeNotPresentException if the annotation is of type
595 * {@link Class} and no definition can be found for the
596 * default class value.
597 * @since 1.5
598 */
599 public Object getDefaultValue() {
600 if (annotationDefault == null)
601 return null;
602 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
603 getReturnType());
604 Object result = AnnotationParser.parseMemberValue(
605 memberType, ByteBuffer.wrap(annotationDefault),
606 sun.misc.SharedSecrets.getJavaLangAccess().
607 getConstantPool(getDeclaringClass()),
608 getDeclaringClass());
609 if (result instanceof sun.reflect.annotation.ExceptionProxy)
610 throw new AnnotationFormatError("Invalid default: " + this);
611 return result;
612 }
613
614 /**
615 * {@inheritDoc}
616 * @throws NullPointerException {@inheritDoc}
617 * @since 1.5
618 */
619 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
620 return super.getAnnotation(annotationClass);
621 }
622
623 /**
624 * {@inheritDoc}
625 * @since 1.5
626 */
627 public Annotation[] getDeclaredAnnotations() {
628 return super.getDeclaredAnnotations();
629 }
630
631 /**
632 * {@inheritDoc}
633 * @since 1.5
634 */
635 @Override
636 public Annotation[][] getParameterAnnotations() {
637 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
638 }
639
640 /**
641 * {@inheritDoc}
642 * @since 1.8
643 */
644 @Override
645 public AnnotatedType getAnnotatedReturnType() {
646 return getAnnotatedReturnType0(getGenericReturnType());
647 }
648
649 @Override
650 void handleParameterNumberMismatch(int resultLength, int numParameters) {
651 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
652 }
653 }