1 /*
2 * Copyright (c) 1996, 2011, 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
70 // Generics infrastructure
71 // Accessor for factory
72 private GenericsFactory getFactory() {
73 // create scope and factory
74 return CoreReflectionFactory.make(this, ConstructorScope.make(this));
75 }
76
77 // Accessor for generic info repository
78 @Override
79 ConstructorRepository getGenericInfo() {
80 // lazily initialize repository if necessary
81 if (genericInfo == null) {
82 // create and cache generic info repository
83 genericInfo =
84 ConstructorRepository.make(getSignature(),
85 getFactory());
86 }
87 return genericInfo; //return cached repository
88 }
89
90 private volatile ConstructorAccessor constructorAccessor;
91 // For sharing of ConstructorAccessors. This branching structure
92 // is currently only two levels deep (i.e., one root Constructor
93 // and potentially many Constructor objects pointing to it.)
94 private Constructor<T> root;
95
96 /**
97 * Package-private constructor used by ReflectAccess to enable
98 * instantiation of these objects in Java code from the java.lang
99 * package via sun.reflect.LangReflectAccess.
100 */
101 Constructor(Class<T> declaringClass,
102 Class<?>[] parameterTypes,
103 Class<?>[] checkedExceptions,
104 int modifiers,
105 int slot,
106 String signature,
107 byte[] annotations,
108 byte[] parameterAnnotations) {
109 this.clazz = declaringClass;
110 this.parameterTypes = parameterTypes;
111 this.exceptionTypes = checkedExceptions;
112 this.modifiers = modifiers;
113 this.slot = slot;
114 this.signature = signature;
115 this.annotations = annotations;
116 this.parameterAnnotations = parameterAnnotations;
117 }
118
119 /**
120 * Package-private routine (exposed to java.lang.Class via
121 * ReflectAccess) which returns a copy of this Constructor. The copy's
122 * "root" field points to this Constructor.
123 */
124 Constructor<T> copy() {
125 // This routine enables sharing of ConstructorAccessor objects
126 // among Constructor objects which refer to the same underlying
127 // method in the VM. (All of this contortion is only necessary
128 // because of the "accessibility" bit in AccessibleObject,
129 // which implicitly requires that new java.lang.reflect
130 // objects be fabricated for each reflective call on Class
131 // objects.)
132 Constructor<T> res = new Constructor<>(clazz,
133 parameterTypes,
134 exceptionTypes, modifiers, slot,
135 signature,
136 annotations,
137 parameterAnnotations);
138 res.root = this;
139 // Might as well eagerly propagate this if already present
140 res.constructorAccessor = constructorAccessor;
141 return res;
142 }
143
144 @Override
145 boolean hasGenericInformation() {
146 return (getSignature() != null);
147 }
148
149 @Override
150 byte[] getAnnotationBytes() {
151 return annotations;
152 }
153
154 /**
155 * {@inheritDoc}
156 */
157 @Override
158 public Class<T> getDeclaringClass() {
159 return clazz;
160 }
161
162 /**
163 * Returns the name of this constructor, as a string. This is
164 * the binary name of the constructor's declaring class.
165 */
166 @Override
167 public String getName() {
168 return getDeclaringClass().getName();
169 }
170
171 /**
172 * {@inheritDoc}
173 */
174 @Override
175 public int getModifiers() {
176 return modifiers;
177 }
178
179 /**
180 * {@inheritDoc}
181 * @throws GenericSignatureFormatError {@inheritDoc}
182 * @since 1.5
183 */
184 @Override
185 @SuppressWarnings({"rawtypes", "unchecked"})
186 public TypeVariable<Constructor<T>>[] getTypeParameters() {
187 if (getSignature() != null) {
188 return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
189 } else
190 return (TypeVariable<Constructor<T>>[])new TypeVariable[0];
191 }
192
193
194 /**
195 * {@inheritDoc}
196 */
197 @Override
198 public Class<?>[] getParameterTypes() {
199 return parameterTypes.clone();
200 }
201
202 /**
203 * {@inheritDoc}
204 * @throws GenericSignatureFormatError {@inheritDoc}
205 * @throws TypeNotPresentException {@inheritDoc}
206 * @throws MalformedParameterizedTypeException {@inheritDoc}
207 * @since 1.5
208 */
209 @Override
210 public Type[] getGenericParameterTypes() {
211 return super.getGenericParameterTypes();
212 }
213
214 /**
215 * {@inheritDoc}
216 */
217 @Override
218 public Class<?>[] getExceptionTypes() {
219 return exceptionTypes.clone();
220 }
221
222
223 /**
224 * {@inheritDoc}
225 * @throws GenericSignatureFormatError {@inheritDoc}
226 * @throws TypeNotPresentException {@inheritDoc}
227 * @throws MalformedParameterizedTypeException {@inheritDoc}
228 * @since 1.5
229 */
230 @Override
231 public Type[] getGenericExceptionTypes() {
232 return super.getGenericExceptionTypes();
233 }
234
235 /**
236 * Compares this {@code Constructor} against the specified object.
237 * Returns true if the objects are the same. Two {@code Constructor} objects are
238 * the same if they were declared by the same class and have the
239 * same formal parameter types.
240 */
241 public boolean equals(Object obj) {
242 if (obj != null && obj instanceof Constructor) {
243 Constructor<?> other = (Constructor<?>)obj;
244 if (getDeclaringClass() == other.getDeclaringClass()) {
245 return equalParamTypes(parameterTypes, other.parameterTypes);
246 }
247 }
248 return false;
249 }
250
251 /**
252 * Returns a hashcode for this {@code Constructor}. The hashcode is
253 * the same as the hashcode for the underlying constructor's
254 * declaring class name.
255 */
256 public int hashCode() {
257 return getDeclaringClass().getName().hashCode();
258 }
259
260 /**
261 * Returns a string describing this {@code Constructor}. The string is
262 * formatted as the constructor access modifiers, if any,
263 * followed by the fully-qualified name of the declaring class,
264 * followed by a parenthesized, comma-separated list of the
265 * constructor's formal parameter types. For example:
266 * <pre>
267 * public java.util.Hashtable(int,float)
268 * </pre>
269 *
270 * <p>The only possible modifiers for constructors are the access
271 * modifiers {@code public}, {@code protected} or
272 * {@code private}. Only one of these may appear, or none if the
273 * constructor has default (package) access.
274 */
275 public String toString() {
276 return sharedToString(Modifier.constructorModifiers(),
277 parameterTypes,
278 exceptionTypes);
279 }
280
281 @Override
282 void specificToStringHeader(StringBuilder sb) {
283 sb.append(Field.getTypeName(getDeclaringClass()));
284 }
285
286 /**
287 * Returns a string describing this {@code Constructor},
288 * including type parameters. The string is formatted as the
289 * constructor access modifiers, if any, followed by an
290 * angle-bracketed comma separated list of the constructor's type
291 * parameters, if any, followed by the fully-qualified name of the
292 * declaring class, followed by a parenthesized, comma-separated
293 * list of the constructor's generic formal parameter types.
294 *
295 * If this constructor was declared to take a variable number of
296 * arguments, instead of denoting the last parameter as
297 * "<tt><i>Type</i>[]</tt>", it is denoted as
298 * "<tt><i>Type</i>...</tt>".
299 *
300 * A space is used to separate access modifiers from one another
301 * and from the type parameters or return type. If there are no
302 * type parameters, the type parameter list is elided; if the type
303 * parameter list is present, a space separates the list from the
304 * class name. If the constructor is declared to throw
305 * exceptions, the parameter list is followed by a space, followed
306 * by the word "{@code throws}" followed by a
307 * comma-separated list of the thrown exception types.
308 *
309 * <p>The only possible modifiers for constructors are the access
310 * modifiers {@code public}, {@code protected} or
311 * {@code private}. Only one of these may appear, or none if the
312 * constructor has default (package) access.
313 *
314 * @return a string describing this {@code Constructor},
315 * include type parameters
316 *
317 * @since 1.5
318 */
319 @Override
320 public String toGenericString() {
321 return sharedToGenericString(Modifier.constructorModifiers());
322 }
323
324 @Override
325 void specificToGenericStringHeader(StringBuilder sb) {
326 specificToStringHeader(sb);
327 }
328
329 /**
330 * Uses the constructor represented by this {@code Constructor} object to
331 * create and initialize a new instance of the constructor's
332 * declaring class, with the specified initialization parameters.
333 * Individual parameters are automatically unwrapped to match
334 * primitive formal parameters, and both primitive and reference
335 * parameters are subject to method invocation conversions as necessary.
336 *
337 * <p>If the number of formal parameters required by the underlying constructor
338 * is 0, the supplied {@code initargs} array may be of length 0 or null.
339 *
340 * <p>If the constructor's declaring class is an inner class in a
341 * non-static context, the first argument to the constructor needs
342 * to be the enclosing instance; see section 15.9.3 of
343 * <cite>The Java™ Language Specification</cite>.
344 *
345 * <p>If the required access and argument checks succeed and the
346 * instantiation will proceed, the constructor's declaring class
347 * is initialized if it has not already been initialized.
348 *
349 * <p>If the constructor completes normally, returns the newly
350 * created and initialized instance.
351 *
352 * @param initargs array of objects to be passed as arguments to
353 * the constructor call; values of primitive types are wrapped in
354 * a wrapper object of the appropriate type (e.g. a {@code float}
355 * in a {@link java.lang.Float Float})
356 *
357 * @return a new object created by calling the constructor
358 * this object represents
359 *
360 * @exception IllegalAccessException if this {@code Constructor} object
361 * is enforcing Java language access control and the underlying
362 * constructor is inaccessible.
363 * @exception IllegalArgumentException if the number of actual
364 * and formal parameters differ; if an unwrapping
365 * conversion for primitive arguments fails; or if,
366 * after possible unwrapping, a parameter value
367 * cannot be converted to the corresponding formal
368 * parameter type by a method invocation conversion; if
369 * this constructor pertains to an enum type.
370 * @exception InstantiationException if the class that declares the
371 * underlying constructor represents an abstract class.
372 * @exception InvocationTargetException if the underlying constructor
373 * throws an exception.
374 * @exception ExceptionInInitializerError if the initialization provoked
375 * by this method fails.
376 */
377 public T newInstance(Object ... initargs)
378 throws InstantiationException, IllegalAccessException,
379 IllegalArgumentException, InvocationTargetException
380 {
381 if (!override) {
382 if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
383 Class<?> caller = Reflection.getCallerClass(2);
384
385 checkAccess(caller, clazz, null, modifiers);
386 }
387 }
388 if ((clazz.getModifiers() & Modifier.ENUM) != 0)
389 throw new IllegalArgumentException("Cannot reflectively create enum objects");
390 ConstructorAccessor ca = constructorAccessor; // read volatile
391 if (ca == null) {
392 ca = acquireConstructorAccessor();
393 }
394 @SuppressWarnings("unchecked")
395 T inst = (T) ca.newInstance(initargs);
396 return inst;
397 }
398
399 /**
400 * {@inheritDoc}
401 * @since 1.5
402 */
403 @Override
404 public boolean isVarArgs() {
405 return super.isVarArgs();
406 }
407
408 /**
409 * {@inheritDoc}
410 * @since 1.5
411 */
412 @Override
413 public boolean isSynthetic() {
414 return super.isSynthetic();
415 }
416
417 // NOTE that there is no synchronization used here. It is correct
418 // (though not efficient) to generate more than one
419 // ConstructorAccessor for a given Constructor. However, avoiding
420 // synchronization will probably make the implementation more
421 // scalable.
422 private ConstructorAccessor acquireConstructorAccessor() {
423 // First check to see if one has been created yet, and take it
424 // if so.
425 ConstructorAccessor tmp = null;
426 if (root != null) tmp = root.getConstructorAccessor();
427 if (tmp != null) {
428 constructorAccessor = tmp;
429 } else {
430 // Otherwise fabricate one and propagate it up to the root
431 tmp = reflectionFactory.newConstructorAccessor(this);
432 setConstructorAccessor(tmp);
433 }
434
435 return tmp;
436 }
437
438 // Returns ConstructorAccessor for this Constructor object, not
439 // looking up the chain to the root
440 ConstructorAccessor getConstructorAccessor() {
441 return constructorAccessor;
442 }
443
444 // Sets the ConstructorAccessor for this Constructor object and
445 // (recursively) its root
446 void setConstructorAccessor(ConstructorAccessor accessor) {
447 constructorAccessor = accessor;
448 // Propagate up
449 if (root != null) {
450 root.setConstructorAccessor(accessor);
451 }
452 }
453
454 int getSlot() {
455 return slot;
456 }
457
458 String getSignature() {
459 return signature;
460 }
461
462 byte[] getRawAnnotations() {
463 return annotations;
464 }
465
466 byte[] getRawParameterAnnotations() {
467 return parameterAnnotations;
468 }
469
470
471 /**
472 * {@inheritDoc}
473 * @throws NullPointerException {@inheritDoc}
474 * @since 1.5
475 */
476 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
477 return super.getAnnotation(annotationClass);
478 }
479
480 /**
481 * {@inheritDoc}
482 * @since 1.5
483 */
484 public Annotation[] getDeclaredAnnotations() {
485 return super.getDeclaredAnnotations();
486 }
487
488 /**
489 * {@inheritDoc}
490 * @since 1.5
491 */
492 @Override
493 public Annotation[][] getParameterAnnotations() {
494 return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
495 }
496
497 @Override
498 void handleParameterNumberMismatch(int resultLength, int numParameters) {
499 Class<?> declaringClass = getDeclaringClass();
500 if (declaringClass.isEnum() ||
501 declaringClass.isAnonymousClass() ||
502 declaringClass.isLocalClass() )
503 return ; // Can't do reliable parameter counting
504 else {
505 if (!declaringClass.isMemberClass() || // top-level
506 // Check for the enclosing instance parameter for
507 // non-static member classes
508 (declaringClass.isMemberClass() &&
509 ((declaringClass.getModifiers() & Modifier.STATIC) == 0) &&
510 resultLength + 1 != numParameters) ) {
511 throw new AnnotationFormatError(
512 "Parameter annotations don't match number of parameters");
513 }
514 }
515 }
516 }