1 /*
2 * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.reflect;
27
28 import sun.reflect.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.lang.annotation.AnnotationFormatError;
36
37 /**
38 * {@code Constructor} provides information about, and access to, a single
39 * constructor for a class.
40 *
41 * <p>{@code Constructor} permits widening conversions to occur when matching the
42 * actual parameters to newInstance() with the underlying
43 * constructor's formal parameters, but throws an
44 * {@code IllegalArgumentException} if a narrowing conversion would occur.
45 *
46 * @param <T> the class in which the constructor is declared
47 *
48 * @see Member
49 * @see java.lang.Class
50 * @see java.lang.Class#getConstructors()
51 * @see java.lang.Class#getConstructor(Class[])
52 * @see java.lang.Class#getDeclaredConstructors()
53 *
54 * @author Kenneth Russell
55 * @author Nakul Saraiya
56 */
57 public final class Constructor<T> extends Executable {
58 private Class<T> clazz;
59 private int slot;
60 private Class<?>[] parameterTypes;
61 private Class<?>[] exceptionTypes;
62 private int modifiers;
63 // Generics and annotations support
64 private transient String signature;
65 // generic info repository; lazily initialized
66 private transient ConstructorRepository genericInfo;
67 private byte[] annotations;
68 private byte[] parameterAnnotations;
69 // This is set by the vm at Constructor creation
70 private byte[] typeAnnotations;
71
72 // Generics infrastructure
73 // Accessor for factory
74 private GenericsFactory getFactory() {
75 // create scope and factory
76 return CoreReflectionFactory.make(this, ConstructorScope.make(this));
77 }
78
79 // Accessor for generic info repository
80 @Override
81 ConstructorRepository getGenericInfo() {
82 // lazily initialize repository if necessary
83 if (genericInfo == null) {
84 // create and cache generic info repository
85 genericInfo =
86 ConstructorRepository.make(getSignature(),
87 getFactory());
88 }
89 return genericInfo; //return cached repository
90 }
91
92 private volatile ConstructorAccessor constructorAccessor;
93 // For sharing of ConstructorAccessors. This branching structure
94 // is currently only two levels deep (i.e., one root Constructor
95 // and potentially many Constructor objects pointing to it.)
96 private Constructor<T> root;
97
98 /**
99 * Package-private constructor used by ReflectAccess to enable
100 * instantiation of these objects in Java code from the java.lang
101 * package via sun.reflect.LangReflectAccess.
102 */
103 Constructor(Class<T> declaringClass,
104 Class<?>[] parameterTypes,
105 Class<?>[] checkedExceptions,
106 int modifiers,
107 int slot,
108 String signature,
109 byte[] annotations,
110 byte[] parameterAnnotations) {
111 this.clazz = declaringClass;
112 this.parameterTypes = parameterTypes;
113 this.exceptionTypes = checkedExceptions;
114 this.modifiers = modifiers;
115 this.slot = slot;
116 this.signature = signature;
117 this.annotations = annotations;
118 this.parameterAnnotations = parameterAnnotations;
119 }
120
121 /**
122 * Package-private routine (exposed to java.lang.Class via
123 * ReflectAccess) which returns a copy of this Constructor. The copy's
124 * "root" field points to this Constructor.
125 */
126 Constructor<T> copy() {
127 // This routine enables sharing of ConstructorAccessor objects
128 // among Constructor objects which refer to the same underlying
129 // method in the VM. (All of this contortion is only necessary
130 // because of the "accessibility" bit in AccessibleObject,
131 // which implicitly requires that new java.lang.reflect
132 // objects be fabricated for each reflective call on Class
133 // objects.)
134 Constructor<T> res = new Constructor<>(clazz,
135 parameterTypes,
136 exceptionTypes, modifiers, slot,
137 signature,
138 annotations,
139 parameterAnnotations);
140 res.root = this;
141 // Might as well eagerly propagate this if already present
142 res.constructorAccessor = constructorAccessor;
143
144 res.typeAnnotations = typeAnnotations;
145 return res;
146 }
147
148 @Override
149 boolean hasGenericInformation() {
150 return (getSignature() != null);
151 }
152
153 @Override
154 byte[] getAnnotationBytes() {
155 return annotations;
156 }
157
158 /**
159 * {@inheritDoc}
160 */
161 @Override
162 public Class<T> getDeclaringClass() {
163 return clazz;
164 }
165
166 /**
167 * Returns the name of this constructor, as a string. This is
168 * the binary name of the constructor's declaring class.
169 */
170 @Override
171 public String getName() {
172 return getDeclaringClass().getName();
173 }
174
175 /**
176 * {@inheritDoc}
177 */
178 @Override
179 public int getModifiers() {
180 return modifiers;
181 }
182
183 /**
184 * {@inheritDoc}
185 * @throws GenericSignatureFormatError {@inheritDoc}
186 * @since 1.5
187 */
188 @Override
189 @SuppressWarnings({"rawtypes", "unchecked"})
190 public TypeVariable<Constructor<T>>[] getTypeParameters() {
191 if (getSignature() != null) {
192 return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
193 } else
194 return (TypeVariable<Constructor<T>>[])new TypeVariable[0];
195 }
196
197
198 /**
199 * {@inheritDoc}
200 */
201 @Override
202 public Class<?>[] getParameterTypes() {
203 return parameterTypes.clone();
204 }
205
206 /**
207 * {@inheritDoc}
208 */
209 public int getParameterCount() { return parameterTypes.length; }
210
211 /**
212 * {@inheritDoc}
213 * @throws GenericSignatureFormatError {@inheritDoc}
214 * @throws TypeNotPresentException {@inheritDoc}
215 * @throws MalformedParameterizedTypeException {@inheritDoc}
216 * @since 1.5
217 */
218 @Override
219 public Type[] getGenericParameterTypes() {
220 return super.getGenericParameterTypes();
221 }
222
223 /**
224 * {@inheritDoc}
225 */
226 @Override
227 public Class<?>[] getExceptionTypes() {
228 return exceptionTypes.clone();
229 }
230
231
232 /**
233 * {@inheritDoc}
234 * @throws GenericSignatureFormatError {@inheritDoc}
235 * @throws TypeNotPresentException {@inheritDoc}
236 * @throws MalformedParameterizedTypeException {@inheritDoc}
237 * @since 1.5
238 */
239 @Override
240 public Type[] getGenericExceptionTypes() {
241 return super.getGenericExceptionTypes();
242 }
243
244 /**
245 * Compares this {@code Constructor} against the specified object.
246 * Returns true if the objects are the same. Two {@code Constructor} objects are
247 * the same if they were declared by the same class and have the
248 * same formal parameter types.
249 */
250 public boolean equals(Object obj) {
251 if (obj != null && obj instanceof Constructor) {
252 Constructor<?> other = (Constructor<?>)obj;
253 if (getDeclaringClass() == other.getDeclaringClass()) {
254 return equalParamTypes(parameterTypes, other.parameterTypes);
255 }
256 }
257 return false;
258 }
259
260 /**
261 * Returns a hashcode for this {@code Constructor}. The hashcode is
262 * the same as the hashcode for the underlying constructor's
263 * declaring class name.
264 */
265 public int hashCode() {
266 return getDeclaringClass().getName().hashCode();
267 }
268
269 /**
270 * Returns a string describing this {@code Constructor}. The string is
271 * formatted as the constructor access modifiers, if any,
272 * followed by the fully-qualified name of the declaring class,
273 * followed by a parenthesized, comma-separated list of the
274 * constructor's formal parameter types. For example:
275 * <pre>
276 * public java.util.Hashtable(int,float)
277 * </pre>
278 *
279 * <p>The only possible modifiers for constructors are the access
280 * modifiers {@code public}, {@code protected} or
281 * {@code private}. Only one of these may appear, or none if the
282 * constructor has default (package) access.
283 */
284 public String toString() {
285 return sharedToString(Modifier.constructorModifiers(),
286 parameterTypes,
287 exceptionTypes);
288 }
289
290 @Override
291 void specificToStringHeader(StringBuilder sb) {
292 sb.append(Field.getTypeName(getDeclaringClass()));
293 }
294
295 /**
296 * Returns a string describing this {@code Constructor},
297 * including type parameters. The string is formatted as the
298 * constructor access modifiers, if any, followed by an
299 * angle-bracketed comma separated list of the constructor's type
300 * parameters, if any, followed by the fully-qualified name of the
301 * declaring class, followed by a parenthesized, comma-separated
302 * list of the constructor's generic formal parameter types.
303 *
304 * If this constructor was declared to take a variable number of
305 * arguments, instead of denoting the last parameter as
306 * "<tt><i>Type</i>[]</tt>", it is denoted as
307 * "<tt><i>Type</i>...</tt>".
308 *
309 * A space is used to separate access modifiers from one another
310 * and from the type parameters or return type. If there are no
311 * type parameters, the type parameter list is elided; if the type
312 * parameter list is present, a space separates the list from the
313 * class name. If the constructor is declared to throw
314 * exceptions, the parameter list is followed by a space, followed
315 * by the word "{@code throws}" followed by a
316 * comma-separated list of the thrown exception types.
317 *
318 * <p>The only possible modifiers for constructors are the access
319 * modifiers {@code public}, {@code protected} or
320 * {@code private}. Only one of these may appear, or none if the
321 * constructor has default (package) access.
322 *
323 * @return a string describing this {@code Constructor},
324 * include type parameters
325 *
326 * @since 1.5
327 */
328 @Override
329 public String toGenericString() {
330 return sharedToGenericString(Modifier.constructorModifiers());
331 }
332
333 @Override
334 void specificToGenericStringHeader(StringBuilder sb) {
335 specificToStringHeader(sb);
336 }
337
338 /**
339 * Uses the constructor represented by this {@code Constructor} object to
340 * create and initialize a new instance of the constructor's
341 * declaring class, with the specified initialization parameters.
342 * Individual parameters are automatically unwrapped to match
343 * primitive formal parameters, and both primitive and reference
344 * parameters are subject to method invocation conversions as necessary.
345 *
346 * <p>If the number of formal parameters required by the underlying constructor
347 * is 0, the supplied {@code initargs} array may be of length 0 or null.
348 *
349 * <p>If the constructor's declaring class is an inner class in a
350 * non-static context, the first argument to the constructor needs
351 * to be the enclosing instance; see section 15.9.3 of
352 * <cite>The Java™ Language Specification</cite>.
353 *
354 * <p>If the required access and argument checks succeed and the
355 * instantiation will proceed, the constructor's declaring class
356 * is initialized if it has not already been initialized.
357 *
358 * <p>If the constructor completes normally, returns the newly
359 * created and initialized instance.
360 *
361 * @param initargs array of objects to be passed as arguments to
362 * the constructor call; values of primitive types are wrapped in
363 * a wrapper object of the appropriate type (e.g. a {@code float}
364 * in a {@link java.lang.Float Float})
365 *
366 * @return a new object created by calling the constructor
367 * this object represents
368 *
369 * @exception IllegalAccessException if this {@code Constructor} object
370 * is enforcing Java language access control and the underlying
371 * constructor is inaccessible.
372 * @exception IllegalArgumentException if the number of actual
373 * and formal parameters differ; if an unwrapping
374 * conversion for primitive arguments fails; or if,
375 * after possible unwrapping, a parameter value
376 * cannot be converted to the corresponding formal
377 * parameter type by a method invocation conversion; if
378 * this constructor pertains to an enum type.
379 * @exception InstantiationException if the class that declares the
380 * underlying constructor represents an abstract class.
381 * @exception InvocationTargetException if the underlying constructor
382 * throws an exception.
383 * @exception ExceptionInInitializerError if the initialization provoked
384 * by this method fails.
385 */
386 public T newInstance(Object ... initargs)
387 throws InstantiationException, IllegalAccessException,
388 IllegalArgumentException, InvocationTargetException
389 {
390 if (!override) {
391 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
392 Class<?> caller = Reflection.getCallerClass(2);
393
394 checkAccess(caller, clazz, null, modifiers);
395 }
396 }
397 if ((clazz.getModifiers() & Modifier.ENUM) != 0)
398 throw new IllegalArgumentException("Cannot reflectively create enum objects");
399 ConstructorAccessor ca = constructorAccessor; // read volatile
400 if (ca == null) {
401 ca = acquireConstructorAccessor();
402 }
403 @SuppressWarnings("unchecked")
404 T inst = (T) ca.newInstance(initargs);
405 return inst;
406 }
407
408 /**
409 * {@inheritDoc}
410 * @since 1.5
411 */
412 @Override
413 public boolean isVarArgs() {
414 return super.isVarArgs();
415 }
416
417 /**
418 * {@inheritDoc}
419 * @jls 13.1 The Form of a Binary
420 * @since 1.5
421 */
422 @Override
423 public boolean isSynthetic() {
424 return super.isSynthetic();
425 }
426
427 // NOTE that there is no synchronization used here. It is correct
428 // (though not efficient) to generate more than one
429 // ConstructorAccessor for a given Constructor. However, avoiding
430 // synchronization will probably make the implementation more
431 // scalable.
432 private ConstructorAccessor acquireConstructorAccessor() {
433 // First check to see if one has been created yet, and take it
434 // if so.
435 ConstructorAccessor tmp = null;
436 if (root != null) tmp = root.getConstructorAccessor();
437 if (tmp != null) {
438 constructorAccessor = tmp;
439 } else {
440 // Otherwise fabricate one and propagate it up to the root
441 tmp = reflectionFactory.newConstructorAccessor(this);
442 setConstructorAccessor(tmp);
443 }
444
445 return tmp;
446 }
447
448 // Returns ConstructorAccessor for this Constructor object, not
449 // looking up the chain to the root
450 ConstructorAccessor getConstructorAccessor() {
451 return constructorAccessor;
452 }
453
454 // Sets the ConstructorAccessor for this Constructor object and
455 // (recursively) its root
456 void setConstructorAccessor(ConstructorAccessor accessor) {
457 constructorAccessor = accessor;
458 // Propagate up
459 if (root != null) {
460 root.setConstructorAccessor(accessor);
461 }
462 }
463
464 int getSlot() {
465 return slot;
466 }
467
468 String getSignature() {
469 return signature;
470 }
471
472 byte[] getRawAnnotations() {
473 return annotations;
474 }
475
476 byte[] getRawParameterAnnotations() {
477 return parameterAnnotations;
478 }
479
480
481 /**
482 * {@inheritDoc}
483 * @throws NullPointerException {@inheritDoc}
484 * @since 1.5
485 */
486 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
487 return super.getAnnotation(annotationClass);
488 }
489
490 /**
491 * {@inheritDoc}
492 * @since 1.5
493 */
494 public Annotation[] getDeclaredAnnotations() {
495 return super.getDeclaredAnnotations();
496 }
497
498 /**
499 * {@inheritDoc}
500 * @since 1.5
501 */
502 @Override
503 public Annotation[][] getParameterAnnotations() {
504 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
505 }
506
507 @Override
508 void handleParameterNumberMismatch(int resultLength, int numParameters) {
509 Class<?> declaringClass = getDeclaringClass();
510 if (declaringClass.isEnum() ||
511 declaringClass.isAnonymousClass() ||
512 declaringClass.isLocalClass() )
513 return ; // Can't do reliable parameter counting
514 else {
515 if (!declaringClass.isMemberClass() || // top-level
516 // Check for the enclosing instance parameter for
517 // non-static member classes
518 (declaringClass.isMemberClass() &&
519 ((declaringClass.getModifiers() & Modifier.STATIC) == 0) &&
520 resultLength + 1 != numParameters) ) {
521 throw new AnnotationFormatError(
522 "Parameter annotations don't match number of parameters");
523 }
524 }
525 }
526 }