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