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