1 /*
2 * Copyright 1996-2006 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.lang.reflect;
27
28 import sun.reflect.ConstructorAccessor;
29 import sun.reflect.Reflection;
30 import sun.reflect.generics.repository.ConstructorRepository;
31 import sun.reflect.generics.factory.CoreReflectionFactory;
32 import sun.reflect.generics.factory.GenericsFactory;
33 import sun.reflect.generics.scope.ConstructorScope;
34 import java.lang.annotation.Annotation;
35 import java.util.Map;
36 import sun.reflect.annotation.AnnotationParser;
37 import java.lang.annotation.AnnotationFormatError;
38 import java.lang.reflect.Modifier;
39
40 /**
41 * {@code Constructor} provides information about, and access to, a single
42 * constructor for a class.
43 *
44 * <p>{@code Constructor} permits widening conversions to occur when matching the
45 * actual parameters to newInstance() with the underlying
46 * constructor's formal parameters, but throws an
47 * {@code IllegalArgumentException} if a narrowing conversion would occur.
48 *
49 * @param <T> the class in which the constructor is declared
50 *
51 * @see Member
52 * @see java.lang.Class
53 * @see java.lang.Class#getConstructors()
54 * @see java.lang.Class#getConstructor(Class[])
55 * @see java.lang.Class#getDeclaredConstructors()
56 *
57 * @author Kenneth Russell
58 * @author Nakul Saraiya
59 */
60 public final
61 class Constructor<T> extends AccessibleObject implements
62 GenericDeclaration,
63 Member {
64
65 private Class<T> clazz;
66 private int slot;
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 ConstructorRepository genericInfo;
74 private byte[] annotations;
75 private byte[] parameterAnnotations;
76
77 // For non-public members or members in package-private classes,
78 // it is necessary to perform somewhat expensive security checks.
79 // If the security check succeeds for a given class, it will
80 // always succeed (it is not affected by the granting or revoking
81 // of permissions); we speed up the check in the common case by
82 // remembering the last Class for which the check succeeded.
83 private volatile Class securityCheckCache;
84
85 // Modifiers that can be applied to a constructor in source code
86 private static final int LANGUAGE_MODIFIERS =
87 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;
88
89 // Generics infrastructure
90 // Accessor for factory
91 private GenericsFactory getFactory() {
92 // create scope and factory
93 return CoreReflectionFactory.make(this, ConstructorScope.make(this));
94 }
95
96 // Accessor for generic info repository
97 private ConstructorRepository getGenericInfo() {
98 // lazily initialize repository if necessary
99 if (genericInfo == null) {
100 // create and cache generic info repository
101 genericInfo =
102 ConstructorRepository.make(getSignature(),
103 getFactory());
104 }
105 return genericInfo; //return cached repository
106 }
107
108 private volatile ConstructorAccessor constructorAccessor;
109 // For sharing of ConstructorAccessors. This branching structure
110 // is currently only two levels deep (i.e., one root Constructor
111 // and potentially many Constructor objects pointing to it.)
112 private Constructor<T> root;
113
114 /**
115 * Package-private constructor used by ReflectAccess to enable
116 * instantiation of these objects in Java code from the java.lang
117 * package via sun.reflect.LangReflectAccess.
118 */
119 Constructor(Class<T> declaringClass,
120 Class[] parameterTypes,
121 Class[] checkedExceptions,
122 int modifiers,
123 int slot,
124 String signature,
125 byte[] annotations,
126 byte[] parameterAnnotations)
127 {
128 this.clazz = declaringClass;
129 this.parameterTypes = parameterTypes;
130 this.exceptionTypes = checkedExceptions;
131 this.modifiers = modifiers;
132 this.slot = slot;
133 this.signature = signature;
134 this.annotations = annotations;
135 this.parameterAnnotations = parameterAnnotations;
136 }
137
138 /**
139 * Package-private routine (exposed to java.lang.Class via
140 * ReflectAccess) which returns a copy of this Constructor. The copy's
141 * "root" field points to this Constructor.
142 */
143 Constructor<T> copy() {
144 // This routine enables sharing of ConstructorAccessor objects
145 // among Constructor 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 Constructor<T> res = new Constructor<T>(clazz,
152 parameterTypes,
153 exceptionTypes, modifiers, slot,
154 signature,
155 annotations,
156 parameterAnnotations);
157 res.root = this;
158 // Might as well eagerly propagate this if already present
159 res.constructorAccessor = constructorAccessor;
160 return res;
161 }
162
163 /**
164 * Returns the {@code Class} object representing the class that declares
165 * the constructor represented by this {@code Constructor} object.
166 */
167 public Class<T> getDeclaringClass() {
168 return clazz;
169 }
170
171 /**
172 * Returns the name of this constructor, as a string. This is
173 * always the same as the simple name of the constructor's declaring
174 * class.
175 */
176 public String getName() {
177 return getDeclaringClass().getName();
178 }
179
180 /**
181 * Returns the Java language modifiers for the constructor
182 * represented by this {@code Constructor} object, as an integer. The
183 * {@code Modifier} class should be used to decode the modifiers.
184 *
185 * @see Modifier
186 */
187 public int getModifiers() {
188 return modifiers;
189 }
190
191 /**
192 * Returns an array of {@code TypeVariable} objects that represent the
193 * type variables declared by the generic declaration represented by this
194 * {@code GenericDeclaration} object, in declaration order. Returns an
195 * array of length 0 if the underlying generic declaration declares no type
196 * variables.
197 *
198 * @return an array of {@code TypeVariable} objects that represent
199 * the type variables declared by this generic declaration
200 * @throws GenericSignatureFormatError if the generic
201 * signature of this generic declaration does not conform to
202 * the format specified in the Java Virtual Machine Specification,
203 * 3rd edition
204 * @since 1.5
205 */
206 public TypeVariable<Constructor<T>>[] getTypeParameters() {
207 if (getSignature() != null) {
208 return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
209 } else
210 return (TypeVariable<Constructor<T>>[])new TypeVariable[0];
211 }
212
213
214 /**
215 * Returns an array of {@code Class} objects that represent the formal
216 * parameter types, in declaration order, of the constructor
217 * represented by this {@code Constructor} object. Returns an array of
218 * length 0 if the underlying constructor takes no parameters.
219 *
220 * @return the parameter types for the constructor this object
221 * represents
222 */
223 public Class<?>[] getParameterTypes() {
224 return (Class<?>[]) parameterTypes.clone();
225 }
226
227
228 /**
229 * Returns an array of {@code Type} objects that represent the formal
230 * parameter types, in declaration order, of the method represented by
231 * this {@code Constructor} object. Returns an array of length 0 if the
232 * underlying method takes no parameters.
233 *
234 * <p>If a formal parameter type is a parameterized type,
235 * the {@code Type} object returned for it must accurately reflect
236 * the actual type parameters used in the source code.
237 *
238 * <p>If a formal parameter type is a type variable or a parameterized
239 * type, it is created. Otherwise, it is resolved.
240 *
241 * @return an array of {@code Type}s that represent the formal
242 * parameter types of the underlying method, in declaration order
243 * @throws GenericSignatureFormatError
244 * if the generic method signature does not conform to the format
245 * specified in the Java Virtual Machine Specification, 3rd edition
246 * @throws TypeNotPresentException if any of the parameter
247 * types of the underlying method refers to a non-existent type
248 * declaration
249 * @throws MalformedParameterizedTypeException if any of
250 * the underlying method's parameter types refer to a parameterized
251 * type that cannot be instantiated for any reason
252 * @since 1.5
253 */
254 public Type[] getGenericParameterTypes() {
255 if (getSignature() != null)
256 return getGenericInfo().getParameterTypes();
257 else
258 return getParameterTypes();
259 }
260
261
262 /**
263 * Returns an array of {@code Class} objects that represent the types
264 * of exceptions declared to be thrown by the underlying constructor
265 * represented by this {@code Constructor} object. Returns an array of
266 * length 0 if the constructor declares no exceptions in its {@code throws} clause.
267 *
268 * @return the exception types declared as being thrown by the
269 * constructor this object represents
270 */
271 public Class<?>[] getExceptionTypes() {
272 return (Class<?>[])exceptionTypes.clone();
273 }
274
275
276 /**
277 * Returns an array of {@code Type} objects that represent the
278 * exceptions declared to be thrown by this {@code Constructor} object.
279 * Returns an array of length 0 if the underlying method declares
280 * no exceptions in its {@code throws} clause.
281 *
282 * <p>If an exception type is a parameterized type, the {@code Type}
283 * object returned for it must accurately reflect the actual type
284 * parameters used in the source code.
285 *
286 * <p>If an exception type is a type variable or a parameterized
287 * type, it is created. Otherwise, it is resolved.
288 *
289 * @return an array of Types that represent the exception types
290 * thrown by the underlying method
291 * @throws GenericSignatureFormatError
292 * if the generic method signature does not conform to the format
293 * specified in the Java Virtual Machine Specification, 3rd edition
294 * @throws TypeNotPresentException if the underlying method's
295 * {@code throws} clause refers to a non-existent type declaration
296 * @throws MalformedParameterizedTypeException if
297 * the underlying method's {@code throws} clause refers to a
298 * parameterized type that cannot be instantiated for any reason
299 * @since 1.5
300 */
301 public Type[] getGenericExceptionTypes() {
302 Type[] result;
303 if (getSignature() != null &&
304 ( (result = getGenericInfo().getExceptionTypes()).length > 0 ))
305 return result;
306 else
307 return getExceptionTypes();
308 }
309
310 /**
311 * Compares this {@code Constructor} against the specified object.
312 * Returns true if the objects are the same. Two {@code Constructor} objects are
313 * the same if they were declared by the same class and have the
314 * same formal parameter types.
315 */
316 public boolean equals(Object obj) {
317 if (obj != null && obj instanceof Constructor) {
318 Constructor other = (Constructor)obj;
319 if (getDeclaringClass() == other.getDeclaringClass()) {
320 /* Avoid unnecessary cloning */
321 Class[] params1 = parameterTypes;
322 Class[] params2 = other.parameterTypes;
323 if (params1.length == params2.length) {
324 for (int i = 0; i < params1.length; i++) {
325 if (params1[i] != params2[i])
326 return false;
327 }
328 return true;
329 }
330 }
331 }
332 return false;
333 }
334
335 /**
336 * Returns a hashcode for this {@code Constructor}. The hashcode is
337 * the same as the hashcode for the underlying constructor's
338 * declaring class name.
339 */
340 public int hashCode() {
341 return getDeclaringClass().getName().hashCode();
342 }
343
344 /**
345 * Returns a string describing this {@code Constructor}. The string is
346 * formatted as the constructor access modifiers, if any,
347 * followed by the fully-qualified name of the declaring class,
348 * followed by a parenthesized, comma-separated list of the
349 * constructor's formal parameter types. For example:
350 * <pre>
351 * public java.util.Hashtable(int,float)
352 * </pre>
353 *
354 * <p>The only possible modifiers for constructors are the access
355 * modifiers {@code public}, {@code protected} or
356 * {@code private}. Only one of these may appear, or none if the
357 * constructor has default (package) access.
358 */
359 public String toString() {
360 try {
361 StringBuffer sb = new StringBuffer();
362 int mod = getModifiers() & LANGUAGE_MODIFIERS;
363 if (mod != 0) {
364 sb.append(Modifier.toString(mod) + " ");
365 }
366 sb.append(Field.getTypeName(getDeclaringClass()));
367 sb.append("(");
368 Class[] params = parameterTypes; // avoid clone
369 for (int j = 0; j < params.length; j++) {
370 sb.append(Field.getTypeName(params[j]));
371 if (j < (params.length - 1))
372 sb.append(",");
373 }
374 sb.append(")");
375 Class[] exceptions = exceptionTypes; // avoid clone
376 if (exceptions.length > 0) {
377 sb.append(" throws ");
378 for (int k = 0; k < exceptions.length; k++) {
379 sb.append(exceptions[k].getName());
380 if (k < (exceptions.length - 1))
381 sb.append(",");
382 }
383 }
384 return sb.toString();
385 } catch (Exception e) {
386 return "<" + e + ">";
387 }
388 }
389
390 /**
391 * Returns a string describing this {@code Constructor},
392 * including type parameters. The string is formatted as the
393 * constructor access modifiers, if any, followed by an
394 * angle-bracketed comma separated list of the constructor's type
395 * parameters, if any, followed by the fully-qualified name of the
396 * declaring class, followed by a parenthesized, comma-separated
397 * list of the constructor's generic formal parameter types.
398 *
399 * A space is used to separate access modifiers from one another
400 * and from the type parameters or return type. If there are no
401 * type parameters, the type parameter list is elided; if the type
402 * parameter list is present, a space separates the list from the
403 * class name. If the constructor is declared to throw
404 * exceptions, the parameter list is followed by a space, followed
405 * by the word "{@code throws}" followed by a
406 * comma-separated list of the thrown exception types.
407 *
408 * <p>The only possible modifiers for constructors are the access
409 * modifiers {@code public}, {@code protected} or
410 * {@code private}. Only one of these may appear, or none if the
411 * constructor has default (package) access.
412 *
413 * @return a string describing this {@code Constructor},
414 * include type parameters
415 *
416 * @since 1.5
417 */
418 public String toGenericString() {
419 try {
420 StringBuilder sb = new StringBuilder();
421 int mod = getModifiers() & LANGUAGE_MODIFIERS;
422 if (mod != 0) {
423 sb.append(Modifier.toString(mod) + " ");
424 }
425 TypeVariable<?>[] typeparms = getTypeParameters();
426 if (typeparms.length > 0) {
427 boolean first = true;
428 sb.append("<");
429 for(TypeVariable<?> typeparm: typeparms) {
430 if (!first)
431 sb.append(",");
432 // Class objects can't occur here; no need to test
433 // and call Class.getName().
434 sb.append(typeparm.toString());
435 first = false;
436 }
437 sb.append("> ");
438 }
439 sb.append(Field.getTypeName(getDeclaringClass()));
440 sb.append("(");
441 Type[] params = getGenericParameterTypes();
442 for (int j = 0; j < params.length; j++) {
443 String param = (params[j] instanceof Class<?>)?
444 Field.getTypeName((Class<?>)params[j]):
445 (params[j].toString());
446 sb.append(param);
447 if (j < (params.length - 1))
448 sb.append(",");
449 }
450 sb.append(")");
451 Type[] exceptions = getGenericExceptionTypes();
452 if (exceptions.length > 0) {
453 sb.append(" throws ");
454 for (int k = 0; k < exceptions.length; k++) {
455 sb.append((exceptions[k] instanceof Class)?
456 ((Class)exceptions[k]).getName():
457 exceptions[k].toString());
458 if (k < (exceptions.length - 1))
459 sb.append(",");
460 }
461 }
462 return sb.toString();
463 } catch (Exception e) {
464 return "<" + e + ">";
465 }
466 }
467
468 /**
469 * Uses the constructor represented by this {@code Constructor} object to
470 * create and initialize a new instance of the constructor's
471 * declaring class, with the specified initialization parameters.
472 * Individual parameters are automatically unwrapped to match
473 * primitive formal parameters, and both primitive and reference
474 * parameters are subject to method invocation conversions as necessary.
475 *
476 * <p>If the number of formal parameters required by the underlying constructor
477 * is 0, the supplied {@code initargs} array may be of length 0 or null.
478 *
479 * <p>If the constructor's declaring class is an inner class in a
480 * non-static context, the first argument to the constructor needs
481 * to be the enclosing instance; see <i>The Java Language
482 * Specification</i>, section 15.9.3.
483 *
484 * <p>If the required access and argument checks succeed and the
485 * instantiation will proceed, the constructor's declaring class
486 * is initialized if it has not already been initialized.
487 *
488 * <p>If the constructor completes normally, returns the newly
489 * created and initialized instance.
490 *
491 * @param initargs array of objects to be passed as arguments to
492 * the constructor call; values of primitive types are wrapped in
493 * a wrapper object of the appropriate type (e.g. a {@code float}
494 * in a {@link java.lang.Float Float})
495 *
496 * @return a new object created by calling the constructor
497 * this object represents
498 *
499 * @exception IllegalAccessException if this {@code Constructor} object
500 * enforces Java language access control and the underlying
501 * constructor is inaccessible.
502 * @exception IllegalArgumentException if the number of actual
503 * and formal parameters differ; if an unwrapping
504 * conversion for primitive arguments fails; or if,
505 * after possible unwrapping, a parameter value
506 * cannot be converted to the corresponding formal
507 * parameter type by a method invocation conversion; if
508 * this constructor pertains to an enum type.
509 * @exception InstantiationException if the class that declares the
510 * underlying constructor represents an abstract class.
511 * @exception InvocationTargetException if the underlying constructor
512 * throws an exception.
513 * @exception ExceptionInInitializerError if the initialization provoked
514 * by this method fails.
515 */
516 public T newInstance(Object ... initargs)
517 throws InstantiationException, IllegalAccessException,
518 IllegalArgumentException, InvocationTargetException
519 {
520 if (!override) {
521 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
522 Class caller = Reflection.getCallerClass(2);
523 if (securityCheckCache != caller) {
524 Reflection.ensureMemberAccess(caller, clazz, null, modifiers);
525 securityCheckCache = caller;
526 }
527 }
528 }
529 if ((clazz.getModifiers() & Modifier.ENUM) != 0)
530 throw new IllegalArgumentException("Cannot reflectively create enum objects");
531 if (constructorAccessor == null) acquireConstructorAccessor();
532 return (T) constructorAccessor.newInstance(initargs);
533 }
534
535 /**
536 * Returns {@code true} if this constructor was declared to take
537 * a variable number of arguments; returns {@code false}
538 * otherwise.
539 *
540 * @return {@code true} if an only if this constructor was declared to
541 * take a variable number of arguments.
542 * @since 1.5
543 */
544 public boolean isVarArgs() {
545 return (getModifiers() & Modifier.VARARGS) != 0;
546 }
547
548 /**
549 * Returns {@code true} if this constructor is a synthetic
550 * constructor; returns {@code false} otherwise.
551 *
552 * @return true if and only if this constructor is a synthetic
553 * constructor as defined by the Java Language Specification.
554 * @since 1.5
555 */
556 public boolean isSynthetic() {
557 return Modifier.isSynthetic(getModifiers());
558 }
559
560 // NOTE that there is no synchronization used here. It is correct
561 // (though not efficient) to generate more than one
562 // ConstructorAccessor for a given Constructor. However, avoiding
563 // synchronization will probably make the implementation more
564 // scalable.
565 private void acquireConstructorAccessor() {
566 // First check to see if one has been created yet, and take it
567 // if so.
568 ConstructorAccessor tmp = null;
569 if (root != null) tmp = root.getConstructorAccessor();
570 if (tmp != null) {
571 constructorAccessor = tmp;
572 return;
573 }
574 // Otherwise fabricate one and propagate it up to the root
575 tmp = reflectionFactory.newConstructorAccessor(this);
576 setConstructorAccessor(tmp);
577 }
578
579 // Returns ConstructorAccessor for this Constructor object, not
580 // looking up the chain to the root
581 ConstructorAccessor getConstructorAccessor() {
582 return constructorAccessor;
583 }
584
585 // Sets the ConstructorAccessor for this Constructor object and
586 // (recursively) its root
587 void setConstructorAccessor(ConstructorAccessor accessor) {
588 constructorAccessor = accessor;
589 // Propagate up
590 if (root != null) {
591 root.setConstructorAccessor(accessor);
592 }
593 }
594
595 int getSlot() {
596 return slot;
597 }
598
599 String getSignature() {
600 return signature;
601 }
602
603 byte[] getRawAnnotations() {
604 return annotations;
605 }
606
607 byte[] getRawParameterAnnotations() {
608 return parameterAnnotations;
609 }
610
611 /**
612 * @throws NullPointerException {@inheritDoc}
613 * @since 1.5
614 */
615 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
616 if (annotationClass == null)
617 throw new NullPointerException();
618
619 return (T) declaredAnnotations().get(annotationClass);
620 }
621
622 private static final Annotation[] EMPTY_ANNOTATION_ARRAY=new Annotation[0];
623
624 /**
625 * @since 1.5
626 */
627 public Annotation[] getDeclaredAnnotations() {
628 return declaredAnnotations().values().toArray(EMPTY_ANNOTATION_ARRAY);
629 }
630
631 private transient Map<Class, Annotation> declaredAnnotations;
632
633 private synchronized Map<Class, Annotation> declaredAnnotations() {
634 if (declaredAnnotations == null) {
635 declaredAnnotations = AnnotationParser.parseAnnotations(
636 annotations, sun.misc.SharedSecrets.getJavaLangAccess().
637 getConstantPool(getDeclaringClass()),
638 getDeclaringClass());
639 }
640 return declaredAnnotations;
641 }
642
643 /**
644 * Returns an array of arrays that represent the annotations on the formal
645 * parameters, in declaration order, of the method represented by
646 * this {@code Constructor} object. (Returns an array of length zero if the
647 * underlying method is parameterless. If the method has one or more
648 * parameters, a nested array of length zero is returned for each parameter
649 * with no annotations.) The annotation objects contained in the returned
650 * arrays are serializable. The caller of this method is free to modify
651 * the returned arrays; it will have no effect on the arrays returned to
652 * other callers.
653 *
654 * @return an array of arrays that represent the annotations on the formal
655 * parameters, in declaration order, of the method represented by this
656 * Constructor object
657 * @since 1.5
658 */
659 public Annotation[][] getParameterAnnotations() {
660 int numParameters = parameterTypes.length;
661 if (parameterAnnotations == null)
662 return new Annotation[numParameters][0];
663
664 Annotation[][] result = AnnotationParser.parseParameterAnnotations(
665 parameterAnnotations,
666 sun.misc.SharedSecrets.getJavaLangAccess().
667 getConstantPool(getDeclaringClass()),
668 getDeclaringClass());
669 if (result.length != numParameters) {
670 Class<?> declaringClass = getDeclaringClass();
671 if (declaringClass.isEnum() ||
672 declaringClass.isAnonymousClass() ||
673 declaringClass.isLocalClass() )
674 ; // Can't do reliable parameter counting
675 else {
676 if (!declaringClass.isMemberClass() || // top-level
677 // Check for the enclosing instance parameter for
678 // non-static member classes
679 (declaringClass.isMemberClass() &&
680 ((declaringClass.getModifiers() & Modifier.STATIC) == 0) &&
681 result.length + 1 != numParameters) ) {
682 throw new AnnotationFormatError(
683 "Parameter annotations don't match number of parameters");
684 }
685 }
686 }
687 return result;
688 }
689 }
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