1 /*
2 * Copyright (c) 1996, 2010, 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.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 * the binary name of the constructor's declaring class.
170 */
171 public String getName() {
172 return getDeclaringClass().getName();
173 }
174
175 /**
176 * Returns the Java language modifiers for the constructor
177 * represented by this {@code Constructor} object, as an integer. The
178 * {@code Modifier} class should be used to decode the modifiers.
179 *
180 * @see Modifier
181 */
182 public int getModifiers() {
183 return modifiers;
184 }
185
186 /**
187 * Returns an array of {@code TypeVariable} objects that represent the
188 * type variables declared by the generic declaration represented by this
189 * {@code GenericDeclaration} object, in declaration order. Returns an
190 * array of length 0 if the underlying generic declaration declares no type
191 * variables.
192 *
193 * @return an array of {@code TypeVariable} objects that represent
194 * the type variables declared by this generic declaration
195 * @throws GenericSignatureFormatError if the generic
196 * signature of this generic declaration does not conform to
197 * the format specified in the Java Virtual Machine Specification,
198 * 3rd edition
199 * @since 1.5
200 */
201 public TypeVariable<Constructor<T>>[] getTypeParameters() {
202 if (getSignature() != null) {
203 return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
204 } else
205 return (TypeVariable<Constructor<T>>[])new TypeVariable[0];
206 }
207
208
209 /**
210 * Returns an array of {@code Class} objects that represent the formal
211 * parameter types, in declaration order, of the constructor
212 * represented by this {@code Constructor} object. Returns an array of
213 * length 0 if the underlying constructor takes no parameters.
214 *
215 * @return the parameter types for the constructor this object
216 * represents
217 */
218 public Class<?>[] getParameterTypes() {
219 return (Class<?>[]) parameterTypes.clone();
220 }
221
222
223 /**
224 * Returns an array of {@code Type} objects that represent the formal
225 * parameter types, in declaration order, of the method represented by
226 * this {@code Constructor} object. Returns an array of length 0 if the
227 * underlying method takes no parameters.
228 *
229 * <p>If a formal parameter type is a parameterized type,
230 * the {@code Type} object returned for it must accurately reflect
231 * the actual type parameters used in the source code.
232 *
233 * <p>If a formal parameter type is a type variable or a parameterized
234 * type, it is created. Otherwise, it is resolved.
235 *
236 * @return an array of {@code Type}s that represent the formal
237 * parameter types of the underlying method, in declaration order
238 * @throws GenericSignatureFormatError
239 * if the generic method signature does not conform to the format
240 * specified in the Java Virtual Machine Specification, 3rd edition
241 * @throws TypeNotPresentException if any of the parameter
242 * types of the underlying method refers to a non-existent type
243 * declaration
244 * @throws MalformedParameterizedTypeException if any of
245 * the underlying method's parameter types refer to a parameterized
246 * type that cannot be instantiated for any reason
247 * @since 1.5
248 */
249 public Type[] getGenericParameterTypes() {
250 if (getSignature() != null)
251 return getGenericInfo().getParameterTypes();
252 else
253 return getParameterTypes();
254 }
255
256
257 /**
258 * Returns an array of {@code Class} objects that represent the types
259 * of exceptions declared to be thrown by the underlying constructor
260 * represented by this {@code Constructor} object. Returns an array of
261 * length 0 if the constructor declares no exceptions in its {@code throws} clause.
262 *
263 * @return the exception types declared as being thrown by the
264 * constructor this object represents
265 */
266 public Class<?>[] getExceptionTypes() {
267 return (Class<?>[])exceptionTypes.clone();
268 }
269
270
271 /**
272 * Returns an array of {@code Type} objects that represent the
273 * exceptions declared to be thrown by this {@code Constructor} object.
274 * Returns an array of length 0 if the underlying method declares
275 * no exceptions in its {@code throws} clause.
276 *
277 * <p>If an exception type is a type variable or a parameterized
278 * type, it is created. Otherwise, it is resolved.
279 *
280 * @return an array of Types that represent the exception types
281 * thrown by the underlying method
282 * @throws GenericSignatureFormatError
283 * if the generic method signature does not conform to the format
284 * specified in the Java Virtual Machine Specification, 3rd edition
285 * @throws TypeNotPresentException if the underlying method's
286 * {@code throws} clause refers to a non-existent type declaration
287 * @throws MalformedParameterizedTypeException if
288 * the underlying method's {@code throws} clause refers to a
289 * parameterized type that cannot be instantiated for any reason
290 * @since 1.5
291 */
292 public Type[] getGenericExceptionTypes() {
293 Type[] result;
294 if (getSignature() != null &&
295 ( (result = getGenericInfo().getExceptionTypes()).length > 0 ))
296 return result;
297 else
298 return getExceptionTypes();
299 }
300
301 /**
302 * Compares this {@code Constructor} against the specified object.
303 * Returns true if the objects are the same. Two {@code Constructor} objects are
304 * the same if they were declared by the same class and have the
305 * same formal parameter types.
306 */
307 public boolean equals(Object obj) {
308 if (obj != null && obj instanceof Constructor) {
309 Constructor<?> other = (Constructor<?>)obj;
310 if (getDeclaringClass() == other.getDeclaringClass()) {
311 /* Avoid unnecessary cloning */
312 Class<?>[] params1 = parameterTypes;
313 Class<?>[] params2 = other.parameterTypes;
314 if (params1.length == params2.length) {
315 for (int i = 0; i < params1.length; i++) {
316 if (params1[i] != params2[i])
317 return false;
318 }
319 return true;
320 }
321 }
322 }
323 return false;
324 }
325
326 /**
327 * Returns a hashcode for this {@code Constructor}. The hashcode is
328 * the same as the hashcode for the underlying constructor's
329 * declaring class name.
330 */
331 public int hashCode() {
332 return getDeclaringClass().getName().hashCode();
333 }
334
335 /**
336 * Returns a string describing this {@code Constructor}. The string is
337 * formatted as the constructor access modifiers, if any,
338 * followed by the fully-qualified name of the declaring class,
339 * followed by a parenthesized, comma-separated list of the
340 * constructor's formal parameter types. For example:
341 * <pre>
342 * public java.util.Hashtable(int,float)
343 * </pre>
344 *
345 * <p>The only possible modifiers for constructors are the access
346 * modifiers {@code public}, {@code protected} or
347 * {@code private}. Only one of these may appear, or none if the
348 * constructor has default (package) access.
349 */
350 public String toString() {
351 try {
352 StringBuffer sb = new StringBuffer();
353 int mod = getModifiers() & Modifier.constructorModifiers();
354 if (mod != 0) {
355 sb.append(Modifier.toString(mod) + " ");
356 }
357 sb.append(Field.getTypeName(getDeclaringClass()));
358 sb.append("(");
359 Class<?>[] params = parameterTypes; // avoid clone
360 for (int j = 0; j < params.length; j++) {
361 sb.append(Field.getTypeName(params[j]));
362 if (j < (params.length - 1))
363 sb.append(",");
364 }
365 sb.append(")");
366 Class<?>[] exceptions = exceptionTypes; // avoid clone
367 if (exceptions.length > 0) {
368 sb.append(" throws ");
369 for (int k = 0; k < exceptions.length; k++) {
370 sb.append(exceptions[k].getName());
371 if (k < (exceptions.length - 1))
372 sb.append(",");
373 }
374 }
375 return sb.toString();
376 } catch (Exception e) {
377 return "<" + e + ">";
378 }
379 }
380
381 /**
382 * Returns a string describing this {@code Constructor},
383 * including type parameters. The string is formatted as the
384 * constructor access modifiers, if any, followed by an
385 * angle-bracketed comma separated list of the constructor's type
386 * parameters, if any, followed by the fully-qualified name of the
387 * declaring class, followed by a parenthesized, comma-separated
388 * list of the constructor's generic formal parameter types.
389 *
390 * If this constructor was declared to take a variable number of
391 * arguments, instead of denoting the last parameter as
392 * "<tt><i>Type</i>[]</tt>", it is denoted as
393 * "<tt><i>Type</i>...</tt>".
394 *
395 * A space is used to separate access modifiers from one another
396 * and from the type parameters or return type. If there are no
397 * type parameters, the type parameter list is elided; if the type
398 * parameter list is present, a space separates the list from the
399 * class name. If the constructor is declared to throw
400 * exceptions, the parameter list is followed by a space, followed
401 * by the word "{@code throws}" followed by a
402 * comma-separated list of the thrown exception types.
403 *
404 * <p>The only possible modifiers for constructors are the access
405 * modifiers {@code public}, {@code protected} or
406 * {@code private}. Only one of these may appear, or none if the
407 * constructor has default (package) access.
408 *
409 * @return a string describing this {@code Constructor},
410 * include type parameters
411 *
412 * @since 1.5
413 */
414 public String toGenericString() {
415 try {
416 StringBuilder sb = new StringBuilder();
417 int mod = getModifiers() & Modifier.constructorModifiers();
418 if (mod != 0) {
419 sb.append(Modifier.toString(mod) + " ");
420 }
421 TypeVariable<?>[] typeparms = getTypeParameters();
422 if (typeparms.length > 0) {
423 boolean first = true;
424 sb.append("<");
425 for(TypeVariable<?> typeparm: typeparms) {
426 if (!first)
427 sb.append(",");
428 // Class objects can't occur here; no need to test
429 // and call Class.getName().
430 sb.append(typeparm.toString());
431 first = false;
432 }
433 sb.append("> ");
434 }
435 sb.append(Field.getTypeName(getDeclaringClass()));
436 sb.append("(");
437 Type[] params = getGenericParameterTypes();
438 for (int j = 0; j < params.length; j++) {
439 String param = (params[j] instanceof Class<?>)?
440 Field.getTypeName((Class<?>)params[j]):
441 (params[j].toString());
442 if (isVarArgs() && (j == params.length - 1)) // replace T[] with T...
443 param = param.replaceFirst("\\[\\]$", "...");
444 sb.append(param);
445 if (j < (params.length - 1))
446 sb.append(",");
447 }
448 sb.append(")");
449 Type[] exceptions = getGenericExceptionTypes();
450 if (exceptions.length > 0) {
451 sb.append(" throws ");
452 for (int k = 0; k < exceptions.length; k++) {
453 sb.append((exceptions[k] instanceof Class)?
454 ((Class<?>)exceptions[k]).getName():
455 exceptions[k].toString());
456 if (k < (exceptions.length - 1))
457 sb.append(",");
458 }
459 }
460 return sb.toString();
461 } catch (Exception e) {
462 return "<" + e + ">";
463 }
464 }
465
466 /**
467 * Uses the constructor represented by this {@code Constructor} object to
468 * create and initialize a new instance of the constructor's
469 * declaring class, with the specified initialization parameters.
470 * Individual parameters are automatically unwrapped to match
471 * primitive formal parameters, and both primitive and reference
472 * parameters are subject to method invocation conversions as necessary.
473 *
474 * <p>If the number of formal parameters required by the underlying constructor
475 * is 0, the supplied {@code initargs} array may be of length 0 or null.
476 *
477 * <p>If the constructor's declaring class is an inner class in a
478 * non-static context, the first argument to the constructor needs
479 * to be the enclosing instance; see <i>The Java Language
480 * Specification</i>, section 15.9.3.
481 *
482 * <p>If the required access and argument checks succeed and the
483 * instantiation will proceed, the constructor's declaring class
484 * is initialized if it has not already been initialized.
485 *
486 * <p>If the constructor completes normally, returns the newly
487 * created and initialized instance.
488 *
489 * @param initargs array of objects to be passed as arguments to
490 * the constructor call; values of primitive types are wrapped in
491 * a wrapper object of the appropriate type (e.g. a {@code float}
492 * in a {@link java.lang.Float Float})
493 *
494 * @return a new object created by calling the constructor
495 * this object represents
496 *
497 * @exception IllegalAccessException if this {@code Constructor} object
498 * enforces Java language access control and the underlying
499 * constructor is inaccessible.
500 * @exception IllegalArgumentException if the number of actual
501 * and formal parameters differ; if an unwrapping
502 * conversion for primitive arguments fails; or if,
503 * after possible unwrapping, a parameter value
504 * cannot be converted to the corresponding formal
505 * parameter type by a method invocation conversion; if
506 * this constructor pertains to an enum type.
507 * @exception InstantiationException if the class that declares the
508 * underlying constructor represents an abstract class.
509 * @exception InvocationTargetException if the underlying constructor
510 * throws an exception.
511 * @exception ExceptionInInitializerError if the initialization provoked
512 * by this method fails.
513 */
514 public T newInstance(Object ... initargs)
515 throws InstantiationException, IllegalAccessException,
516 IllegalArgumentException, InvocationTargetException
517 {
518 if (!override) {
519 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
520 Class<?> caller = Reflection.getCallerClass(2);
521 if (securityCheckCache != caller) {
522 Reflection.ensureMemberAccess(caller, clazz, null, modifiers);
523 securityCheckCache = caller;
524 }
525 }
526 }
527 if ((clazz.getModifiers() & Modifier.ENUM) != 0)
528 throw new IllegalArgumentException("Cannot reflectively create enum objects");
529 if (constructorAccessor == null) acquireConstructorAccessor();
530 return (T) constructorAccessor.newInstance(initargs);
531 }
532
533 /**
534 * Returns {@code true} if this constructor was declared to take
535 * a variable number of arguments; returns {@code false}
536 * otherwise.
537 *
538 * @return {@code true} if an only if this constructor was declared to
539 * take a variable number of arguments.
540 * @since 1.5
541 */
542 public boolean isVarArgs() {
543 return (getModifiers() & Modifier.VARARGS) != 0;
544 }
545
546 /**
547 * Returns {@code true} if this constructor is a synthetic
548 * constructor; returns {@code false} otherwise.
549 *
550 * @return true if and only if this constructor is a synthetic
551 * constructor as defined by the Java Language Specification.
552 * @since 1.5
553 */
554 public boolean isSynthetic() {
555 return Modifier.isSynthetic(getModifiers());
556 }
557
558 // NOTE that there is no synchronization used here. It is correct
559 // (though not efficient) to generate more than one
560 // ConstructorAccessor for a given Constructor. However, avoiding
561 // synchronization will probably make the implementation more
562 // scalable.
563 private void acquireConstructorAccessor() {
564 // First check to see if one has been created yet, and take it
565 // if so.
566 ConstructorAccessor tmp = null;
567 if (root != null) tmp = root.getConstructorAccessor();
568 if (tmp != null) {
569 constructorAccessor = tmp;
570 return;
571 }
572 // Otherwise fabricate one and propagate it up to the root
573 tmp = reflectionFactory.newConstructorAccessor(this);
574 setConstructorAccessor(tmp);
575 }
576
577 // Returns ConstructorAccessor for this Constructor object, not
578 // looking up the chain to the root
579 ConstructorAccessor getConstructorAccessor() {
580 return constructorAccessor;
581 }
582
583 // Sets the ConstructorAccessor for this Constructor object and
584 // (recursively) its root
585 void setConstructorAccessor(ConstructorAccessor accessor) {
586 constructorAccessor = accessor;
587 // Propagate up
588 if (root != null) {
589 root.setConstructorAccessor(accessor);
590 }
591 }
592
593 int getSlot() {
594 return slot;
595 }
596
597 String getSignature() {
598 return signature;
599 }
600
601 byte[] getRawAnnotations() {
602 return annotations;
603 }
604
605 byte[] getRawParameterAnnotations() {
606 return parameterAnnotations;
607 }
608
609 /**
610 * @throws NullPointerException {@inheritDoc}
611 * @since 1.5
612 */
613 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
614 if (annotationClass == null)
615 throw new NullPointerException();
616
617 return (T) declaredAnnotations().get(annotationClass);
618 }
619
620 /**
621 * @since 1.5
622 */
623 public Annotation[] getDeclaredAnnotations() {
624 return AnnotationParser.toArray(declaredAnnotations());
625 }
626
627 private transient Map<Class<? extends Annotation>, Annotation> declaredAnnotations;
628
629 private synchronized Map<Class<? extends Annotation>, Annotation> declaredAnnotations() {
630 if (declaredAnnotations == null) {
631 declaredAnnotations = AnnotationParser.parseAnnotations(
632 annotations, sun.misc.SharedSecrets.getJavaLangAccess().
633 getConstantPool(getDeclaringClass()),
634 getDeclaringClass());
635 }
636 return declaredAnnotations;
637 }
638
639 /**
640 * Returns an array of arrays that represent the annotations on the formal
641 * parameters, in declaration order, of the method represented by
642 * this {@code Constructor} object. (Returns an array of length zero if the
643 * underlying method is parameterless. If the method has one or more
644 * parameters, a nested array of length zero is returned for each parameter
645 * with no annotations.) The annotation objects contained in the returned
646 * arrays are serializable. The caller of this method is free to modify
647 * the returned arrays; it will have no effect on the arrays returned to
648 * other callers.
649 *
650 * @return an array of arrays that represent the annotations on the formal
651 * parameters, in declaration order, of the method represented by this
652 * Constructor object
653 * @since 1.5
654 */
655 public Annotation[][] getParameterAnnotations() {
656 int numParameters = parameterTypes.length;
657 if (parameterAnnotations == null)
658 return new Annotation[numParameters][0];
659
660 Annotation[][] result = AnnotationParser.parseParameterAnnotations(
661 parameterAnnotations,
662 sun.misc.SharedSecrets.getJavaLangAccess().
663 getConstantPool(getDeclaringClass()),
664 getDeclaringClass());
665 if (result.length != numParameters) {
666 Class<?> declaringClass = getDeclaringClass();
667 if (declaringClass.isEnum() ||
668 declaringClass.isAnonymousClass() ||
669 declaringClass.isLocalClass() )
670 ; // Can't do reliable parameter counting
671 else {
672 if (!declaringClass.isMemberClass() || // top-level
673 // Check for the enclosing instance parameter for
674 // non-static member classes
675 (declaringClass.isMemberClass() &&
676 ((declaringClass.getModifiers() & Modifier.STATIC) == 0) &&
677 result.length + 1 != numParameters) ) {
678 throw new AnnotationFormatError(
679 "Parameter annotations don't match number of parameters");
680 }
681 }
682 }
683 return result;
684 }
685 }