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 jdk.internal.HotSpotIntrinsicCandidate;
29 import sun.reflect.CallerSensitive;
30 import sun.reflect.MethodAccessor;
31 import sun.reflect.Reflection;
32 import sun.reflect.generics.repository.MethodRepository;
33 import sun.reflect.generics.factory.CoreReflectionFactory;
34 import sun.reflect.generics.factory.GenericsFactory;
35 import sun.reflect.generics.scope.MethodScope;
36 import sun.reflect.annotation.AnnotationType;
37 import sun.reflect.annotation.AnnotationParser;
38 import java.lang.annotation.Annotation;
39 import java.lang.annotation.AnnotationFormatError;
40 import java.nio.ByteBuffer;
41
42 /**
43 * A {@code Method} provides information about, and access to, a single method
44 * on a class or interface. The reflected method may be a class method
45 * or an instance method (including an abstract method).
46 *
47 * <p>A {@code Method} permits widening conversions to occur when matching the
48 * actual parameters to invoke with the underlying method's formal
49 * parameters, but it throws an {@code IllegalArgumentException} if a
50 * narrowing conversion would occur.
51 *
52 * @see Member
53 * @see java.lang.Class
54 * @see java.lang.Class#getMethods()
55 * @see java.lang.Class#getMethod(String, Class[])
56 * @see java.lang.Class#getDeclaredMethods()
57 * @see java.lang.Class#getDeclaredMethod(String, Class[])
58 *
59 * @author Kenneth Russell
60 * @author Nakul Saraiya
61 */
62 public final class Method extends Executable {
63 private Class<?> clazz;
64 private int slot;
65 // This is guaranteed to be interned by the VM in the 1.4
66 // reflection implementation
67 private String name;
68 private Class<?> returnType;
69 private Class<?>[] parameterTypes;
70 private Class<?>[] exceptionTypes;
71 private int modifiers;
72 // Generics and annotations support
73 private transient String signature;
74 // generic info repository; lazily initialized
75 private transient MethodRepository genericInfo;
76 private byte[] annotations;
77 private byte[] parameterAnnotations;
78 private byte[] annotationDefault;
79 private volatile MethodAccessor methodAccessor;
80 // For sharing of MethodAccessors. This branching structure is
81 // currently only two levels deep (i.e., one root Method and
82 // potentially many Method objects pointing to it.)
83 //
84 // If this branching structure would ever contain cycles, deadlocks can
85 // occur in annotation code.
86 private Method root;
87
88 // Generics infrastructure
89 private String getGenericSignature() {return signature;}
90
91 // Accessor for factory
92 private GenericsFactory getFactory() {
93 // create scope and factory
94 return CoreReflectionFactory.make(this, MethodScope.make(this));
95 }
96
97 // Accessor for generic info repository
98 @Override
99 MethodRepository getGenericInfo() {
100 // lazily initialize repository if necessary
101 if (genericInfo == null) {
102 // create and cache generic info repository
103 genericInfo = MethodRepository.make(getGenericSignature(),
104 getFactory());
105 }
106 return genericInfo; //return cached repository
107 }
108
109 /**
110 * Package-private constructor used by ReflectAccess to enable
111 * instantiation of these objects in Java code from the java.lang
112 * package via sun.reflect.LangReflectAccess.
113 */
114 Method(Class<?> declaringClass,
115 String name,
116 Class<?>[] parameterTypes,
117 Class<?> returnType,
118 Class<?>[] checkedExceptions,
119 int modifiers,
120 int slot,
121 String signature,
122 byte[] annotations,
123 byte[] parameterAnnotations,
124 byte[] annotationDefault) {
125 this.clazz = declaringClass;
126 this.name = name;
127 this.parameterTypes = parameterTypes;
128 this.returnType = returnType;
129 this.exceptionTypes = checkedExceptions;
130 this.modifiers = modifiers;
131 this.slot = slot;
132 this.signature = signature;
133 this.annotations = annotations;
134 this.parameterAnnotations = parameterAnnotations;
135 this.annotationDefault = annotationDefault;
136 }
137
138 /**
139 * Package-private routine (exposed to java.lang.Class via
140 * ReflectAccess) which returns a copy of this Method. The copy's
141 * "root" field points to this Method.
142 */
143 Method copy() {
144 // This routine enables sharing of MethodAccessor objects
145 // among Method objects which refer to the same underlying
146 // method in the VM. (All of this contortion is only necessary
147 // because of the "accessibility" bit in AccessibleObject,
148 // which implicitly requires that new java.lang.reflect
149 // objects be fabricated for each reflective call on Class
150 // objects.)
151 if (this.root != null)
152 throw new IllegalArgumentException("Can not copy a non-root Method");
153
154 Method res = new Method(clazz, name, parameterTypes, returnType,
155 exceptionTypes, modifiers, slot, signature,
156 annotations, parameterAnnotations, annotationDefault);
157 res.root = this;
158 // Might as well eagerly propagate this if already present
159 res.methodAccessor = methodAccessor;
160 return res;
161 }
162
163 /**
164 * Used by Excecutable for annotation sharing.
165 */
166 @Override
167 Executable getRoot() {
168 return root;
169 }
170
171 @Override
172 boolean hasGenericInformation() {
173 return (getGenericSignature() != null);
174 }
175
176 @Override
177 byte[] getAnnotationBytes() {
178 return annotations;
179 }
180
181 /**
182 * {@inheritDoc}
183 */
184 @Override
185 public Class<?> getDeclaringClass() {
186 return clazz;
187 }
188
189 /**
190 * Returns the name of the method represented by this {@code Method}
191 * object, as a {@code String}.
192 */
193 @Override
194 public String getName() {
195 return name;
196 }
197
198 /**
199 * {@inheritDoc}
200 */
201 @Override
202 public int getModifiers() {
203 return modifiers;
204 }
205
206 /**
207 * {@inheritDoc}
208 * @throws GenericSignatureFormatError {@inheritDoc}
209 * @since 1.5
210 */
211 @Override
212 @SuppressWarnings({"rawtypes", "unchecked"})
213 public TypeVariable<Method>[] getTypeParameters() {
214 if (getGenericSignature() != null)
215 return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
216 else
217 return (TypeVariable<Method>[])new TypeVariable[0];
218 }
219
220 /**
221 * Returns a {@code Class} object that represents the formal return type
222 * of the method represented by this {@code Method} object.
223 *
224 * @return the return type for the method this object represents
225 */
226 public Class<?> getReturnType() {
227 return returnType;
228 }
229
230 /**
231 * Returns a {@code Type} object that represents the formal return
232 * type of the method represented by this {@code Method} object.
233 *
234 * <p>If the return type is a parameterized type,
235 * the {@code Type} object returned must accurately reflect
236 * the actual type parameters used in the source code.
237 *
238 * <p>If the return type is a type variable or a parameterized type, it
239 * is created. Otherwise, it is resolved.
240 *
241 * @return a {@code Type} object that represents the formal return
242 * type of the underlying method
243 * @throws GenericSignatureFormatError
244 * if the generic method signature does not conform to the format
245 * specified in
246 * <cite>The Java™ Virtual Machine Specification</cite>
247 * @throws TypeNotPresentException if the underlying method's
248 * return type refers to a non-existent type declaration
249 * @throws MalformedParameterizedTypeException if the
250 * underlying method's return typed refers to a parameterized
251 * type that cannot be instantiated for any reason
252 * @since 1.5
253 */
254 public Type getGenericReturnType() {
255 if (getGenericSignature() != null) {
256 return getGenericInfo().getReturnType();
257 } else { return getReturnType();}
258 }
259
260 /**
261 * {@inheritDoc}
262 */
263 @Override
264 public Class<?>[] getParameterTypes() {
265 return parameterTypes.clone();
266 }
267
268 /**
269 * {@inheritDoc}
270 * @since 1.8
271 */
272 public int getParameterCount() { return parameterTypes.length; }
273
274
275 /**
276 * {@inheritDoc}
277 * @throws GenericSignatureFormatError {@inheritDoc}
278 * @throws TypeNotPresentException {@inheritDoc}
279 * @throws MalformedParameterizedTypeException {@inheritDoc}
280 * @since 1.5
281 */
282 @Override
283 public Type[] getGenericParameterTypes() {
284 return super.getGenericParameterTypes();
285 }
286
287 /**
288 * {@inheritDoc}
289 */
290 @Override
291 public Class<?>[] getExceptionTypes() {
292 return exceptionTypes.clone();
293 }
294
295 /**
296 * {@inheritDoc}
297 * @throws GenericSignatureFormatError {@inheritDoc}
298 * @throws TypeNotPresentException {@inheritDoc}
299 * @throws MalformedParameterizedTypeException {@inheritDoc}
300 * @since 1.5
301 */
302 @Override
303 public Type[] getGenericExceptionTypes() {
304 return super.getGenericExceptionTypes();
305 }
306
307 /**
308 * Compares this {@code Method} against the specified object. Returns
309 * true if the objects are the same. Two {@code Methods} are the same if
310 * they were declared by the same class and have the same name
311 * and formal parameter types and return type.
312 */
313 public boolean equals(Object obj) {
314 if (obj != null && obj instanceof Method) {
315 Method other = (Method)obj;
316 if ((getDeclaringClass() == other.getDeclaringClass())
317 && (getName() == other.getName())) {
318 if (!returnType.equals(other.getReturnType()))
319 return false;
320 return equalParamTypes(parameterTypes, other.parameterTypes);
321 }
322 }
323 return false;
324 }
325
326 /**
327 * Returns a hashcode for this {@code Method}. The hashcode is computed
328 * as the exclusive-or of the hashcodes for the underlying
329 * method's declaring class name and the method's name.
330 */
331 public int hashCode() {
332 return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
333 }
334
335 /**
336 * Returns a string describing this {@code Method}. The string is
337 * formatted as the method access modifiers, if any, followed by
338 * the method return type, followed by a space, followed by the
339 * class declaring the method, followed by a period, followed by
340 * the method name, followed by a parenthesized, comma-separated
341 * list of the method's formal parameter types. If the method
342 * throws checked exceptions, the parameter list is followed by a
343 * space, followed by the word throws followed by a
344 * comma-separated list of the thrown exception types.
345 * For example:
346 * <pre>
347 * public boolean java.lang.Object.equals(java.lang.Object)
348 * </pre>
349 *
350 * <p>The access modifiers are placed in canonical order as
351 * specified by "The Java Language Specification". This is
352 * {@code public}, {@code protected} or {@code private} first,
353 * and then other modifiers in the following order:
354 * {@code abstract}, {@code default}, {@code static}, {@code final},
355 * {@code synchronized}, {@code native}, {@code strictfp}.
356 *
357 * @return a string describing this {@code Method}
358 *
359 * @jls 8.4.3 Method Modifiers
360 * @jls 9.4 Method Declarations
361 * @jls 9.6.1 Annotation Type Elements
362 */
363 public String toString() {
364 return sharedToString(Modifier.methodModifiers(),
365 isDefault(),
366 parameterTypes,
367 exceptionTypes);
368 }
369
370 @Override
371 void specificToStringHeader(StringBuilder sb) {
372 sb.append(getReturnType().getTypeName()).append(' ');
373 sb.append(getDeclaringClass().getTypeName()).append('.');
374 sb.append(getName());
375 }
376
377 /**
378 * Returns a string describing this {@code Method}, including
379 * type parameters. The string is formatted as the method access
380 * modifiers, if any, followed by an angle-bracketed
381 * comma-separated list of the method's type parameters, if any,
382 * followed by the method's generic return type, followed by a
383 * space, followed by the class declaring the method, followed by
384 * a period, followed by the method name, followed by a
385 * parenthesized, comma-separated list of the method's generic
386 * formal parameter types.
387 *
388 * If this method was declared to take a variable number of
389 * arguments, instead of denoting the last parameter as
390 * "<tt><i>Type</i>[]</tt>", it is denoted as
391 * "<tt><i>Type</i>...</tt>".
392 *
393 * A space is used to separate access modifiers from one another
394 * and from the type parameters or return type. If there are no
395 * type parameters, the type parameter list is elided; if the type
396 * parameter list is present, a space separates the list from the
397 * class name. If the method is declared to throw exceptions, the
398 * parameter list is followed by a space, followed by the word
399 * throws followed by a comma-separated list of the generic thrown
400 * exception types.
401 *
402 * <p>The access modifiers are placed in canonical order as
403 * specified by "The Java Language Specification". This is
404 * {@code public}, {@code protected} or {@code private} first,
405 * and then other modifiers in the following order:
406 * {@code abstract}, {@code default}, {@code static}, {@code final},
407 * {@code synchronized}, {@code native}, {@code strictfp}.
408 *
409 * @return a string describing this {@code Method},
410 * include type parameters
411 *
412 * @since 1.5
413 *
414 * @jls 8.4.3 Method Modifiers
415 * @jls 9.4 Method Declarations
416 * @jls 9.6.1 Annotation Type Elements
417 */
418 @Override
419 public String toGenericString() {
420 return sharedToGenericString(Modifier.methodModifiers(), isDefault());
421 }
422
423 @Override
424 void specificToGenericStringHeader(StringBuilder sb) {
425 Type genRetType = getGenericReturnType();
426 sb.append(genRetType.getTypeName()).append(' ');
427 sb.append(getDeclaringClass().getTypeName()).append('.');
428 sb.append(getName());
429 }
430
431 /**
432 * Invokes the underlying method represented by this {@code Method}
433 * object, on the specified object with the specified parameters.
434 * Individual parameters are automatically unwrapped to match
435 * primitive formal parameters, and both primitive and reference
436 * parameters are subject to method invocation conversions as
437 * necessary.
438 *
439 * <p>If the underlying method is static, then the specified {@code obj}
440 * argument is ignored. It may be null.
441 *
442 * <p>If the number of formal parameters required by the underlying method is
443 * 0, the supplied {@code args} array may be of length 0 or null.
444 *
445 * <p>If the underlying method is an instance method, it is invoked
446 * using dynamic method lookup as documented in The Java Language
447 * Specification, Second Edition, section 15.12.4.4; in particular,
448 * overriding based on the runtime type of the target object will occur.
449 *
450 * <p>If the underlying method is static, the class that declared
451 * the method is initialized if it has not already been initialized.
452 *
453 * <p>If the method completes normally, the value it returns is
454 * returned to the caller of invoke; if the value has a primitive
455 * type, it is first appropriately wrapped in an object. However,
456 * if the value has the type of an array of a primitive type, the
457 * elements of the array are <i>not</i> wrapped in objects; in
458 * other words, an array of primitive type is returned. If the
459 * underlying method return type is void, the invocation returns
460 * null.
461 *
462 * @param obj the object the underlying method is invoked from
463 * @param args the arguments used for the method call
464 * @return the result of dispatching the method represented by
465 * this object on {@code obj} with parameters
466 * {@code args}
467 *
468 * @exception IllegalAccessException if this {@code Method} object
469 * is enforcing Java language access control and the underlying
470 * method is inaccessible.
471 * @exception IllegalArgumentException if the method is an
472 * instance method and the specified object argument
473 * is not an instance of the class or interface
474 * declaring the underlying method (or of a subclass
475 * or implementor thereof); if the number of actual
476 * and formal parameters differ; if an unwrapping
477 * conversion for primitive arguments fails; or if,
478 * after possible unwrapping, a parameter value
479 * cannot be converted to the corresponding formal
480 * parameter type by a method invocation conversion.
481 * @exception InvocationTargetException if the underlying method
482 * throws an exception.
483 * @exception NullPointerException if the specified object is null
484 * and the method is an instance method.
485 * @exception ExceptionInInitializerError if the initialization
486 * provoked by this method fails.
487 */
488 @CallerSensitive
489 @HotSpotIntrinsicCandidate
490 public Object invoke(Object obj, Object... args)
491 throws IllegalAccessException, IllegalArgumentException,
492 InvocationTargetException
493 {
494 if (!override) {
495 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
496 Class<?> caller = Reflection.getCallerClass();
497 checkAccess(caller, clazz, obj, modifiers);
498 }
499 }
500 MethodAccessor ma = methodAccessor; // read volatile
501 if (ma == null) {
502 ma = acquireMethodAccessor();
503 }
504 return ma.invoke(obj, args);
505 }
506
507 /**
508 * Returns {@code true} if this method is a bridge
509 * method; returns {@code false} otherwise.
510 *
511 * @return true if and only if this method is a bridge
512 * method as defined by the Java Language Specification.
513 * @since 1.5
514 */
515 public boolean isBridge() {
516 return (getModifiers() & Modifier.BRIDGE) != 0;
517 }
518
519 /**
520 * {@inheritDoc}
521 * @since 1.5
522 */
523 @Override
524 public boolean isVarArgs() {
525 return super.isVarArgs();
526 }
527
528 /**
529 * {@inheritDoc}
530 * @jls 13.1 The Form of a Binary
531 * @since 1.5
532 */
533 @Override
534 public boolean isSynthetic() {
535 return super.isSynthetic();
536 }
537
538 /**
539 * Returns {@code true} if this method is a default
540 * method; returns {@code false} otherwise.
541 *
542 * A default method is a public non-abstract instance method, that
543 * is, a non-static method with a body, declared in an interface
544 * type.
545 *
546 * @return true if and only if this method is a default
547 * method as defined by the Java Language Specification.
548 * @since 1.8
549 */
550 public boolean isDefault() {
551 // Default methods are public non-abstract instance methods
552 // declared in an interface.
553 return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
554 Modifier.PUBLIC) && getDeclaringClass().isInterface();
555 }
556
557 // NOTE that there is no synchronization used here. It is correct
558 // (though not efficient) to generate more than one MethodAccessor
559 // for a given Method. However, avoiding synchronization will
560 // probably make the implementation more scalable.
561 private MethodAccessor acquireMethodAccessor() {
562 // First check to see if one has been created yet, and take it
563 // if so
564 MethodAccessor tmp = null;
565 if (root != null) tmp = root.getMethodAccessor();
566 if (tmp != null) {
567 methodAccessor = tmp;
568 } else {
569 // Otherwise fabricate one and propagate it up to the root
570 tmp = reflectionFactory.newMethodAccessor(this);
571 setMethodAccessor(tmp);
572 }
573
574 return tmp;
575 }
576
577 // Returns MethodAccessor for this Method object, not looking up
578 // the chain to the root
579 MethodAccessor getMethodAccessor() {
580 return methodAccessor;
581 }
582
583 // Sets the MethodAccessor for this Method object and
584 // (recursively) its root
585 void setMethodAccessor(MethodAccessor accessor) {
586 methodAccessor = accessor;
587 // Propagate up
588 if (root != null) {
589 root.setMethodAccessor(accessor);
590 }
591 }
592
593 /**
594 * Returns the default value for the annotation member represented by
595 * this {@code Method} instance. If the member is of a primitive type,
596 * an instance of the corresponding wrapper type is returned. Returns
597 * null if no default is associated with the member, or if the method
598 * instance does not represent a declared member of an annotation type.
599 *
600 * @return the default value for the annotation member represented
601 * by this {@code Method} instance.
602 * @throws TypeNotPresentException if the annotation is of type
603 * {@link Class} and no definition can be found for the
604 * default class value.
605 * @since 1.5
606 */
607 public Object getDefaultValue() {
608 if (annotationDefault == null)
609 return null;
610 Class<?> memberType = AnnotationType.invocationHandlerReturnType(
611 getReturnType());
612 Object result = AnnotationParser.parseMemberValue(
613 memberType, ByteBuffer.wrap(annotationDefault),
614 sun.misc.SharedSecrets.getJavaLangAccess().
615 getConstantPool(getDeclaringClass()),
616 getDeclaringClass());
617 if (result instanceof sun.reflect.annotation.ExceptionProxy)
618 throw new AnnotationFormatError("Invalid default: " + this);
619 return result;
620 }
621
622 /**
623 * {@inheritDoc}
624 * @throws NullPointerException {@inheritDoc}
625 * @since 1.5
626 */
627 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
628 return super.getAnnotation(annotationClass);
629 }
630
631 /**
632 * {@inheritDoc}
633 * @since 1.5
634 */
635 public Annotation[] getDeclaredAnnotations() {
636 return super.getDeclaredAnnotations();
637 }
638
639 /**
640 * {@inheritDoc}
641 * @since 1.5
642 */
643 @Override
644 public Annotation[][] getParameterAnnotations() {
645 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
646 }
647
648 /**
649 * {@inheritDoc}
650 * @since 1.8
651 */
652 @Override
653 public AnnotatedType getAnnotatedReturnType() {
654 return getAnnotatedReturnType0(getGenericReturnType());
655 }
656
657 @Override
658 void handleParameterNumberMismatch(int resultLength, int numParameters) {
659 throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
660 }
661 }