1 /*
   2  * Copyright (c) 2008, 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 package com.sun.beans.finder;
  26 
  27 import com.sun.beans.WeakCache;
  28 
  29 import java.lang.reflect.Constructor;
  30 import java.lang.reflect.Modifier;
  31 
  32 import static sun.reflect.misc.ReflectUtil.isPackageAccessible;
  33 
  34 /**
  35  * This utility class provides {@code static} methods
  36  * to find a public constructor with specified parameter types
  37  * in specified class.
  38  *
  39  * @since 1.7
  40  *
  41  * @author Sergey A. Malenkov
  42  */
  43 public final class ConstructorFinder extends AbstractFinder<Constructor<?>> {
  44     private static final WeakCache<Signature, Constructor<?>> CACHE = new WeakCache<Signature, Constructor<?>>();
  45 
  46     /**
  47      * Finds public constructor
  48      * that is declared in public class.
  49      *
  50      * @param type  the class that can have constructor
  51      * @param args  parameter types that is used to find constructor
  52      * @return object that represents found constructor
  53      * @throws NoSuchMethodException if constructor could not be found
  54      *                               or some constructors are found
  55      */
  56     public static Constructor<?> findConstructor(Class<?> type, Class<?>...args) throws NoSuchMethodException {
  57         if (type.isPrimitive()) {
  58             throw new NoSuchMethodException("Primitive wrapper does not contain constructors");
  59         }
  60         if (type.isInterface()) {
  61             throw new NoSuchMethodException("Interface does not contain constructors");
  62         }
  63         if (Modifier.isAbstract(type.getModifiers())) {
  64             throw new NoSuchMethodException("Abstract class cannot be instantiated");
  65         }
  66         if (!Modifier.isPublic(type.getModifiers()) || !isPackageAccessible(type)) {
  67             throw new NoSuchMethodException("Class is not accessible");
  68         }
  69         PrimitiveWrapperMap.replacePrimitivesWithWrappers(args);
  70         Signature signature = new Signature(type, args);
  71 
  72         Constructor<?> constructor = CACHE.get(signature);
  73         if (constructor != null) {
  74             return constructor;
  75         }
  76         constructor = new ConstructorFinder(args).find(type.getConstructors());
  77         CACHE.put(signature, constructor);
  78         return constructor;
  79     }
  80 
  81     /**
  82      * Creates constructor finder with specified array of parameter types.
  83      *
  84      * @param args  the array of parameter types
  85      */
  86     private ConstructorFinder(Class<?>[] args) {
  87         super(args);
  88     }
  89 
  90     /**
  91      * Returns an array of {@code Class} objects
  92      * that represent the formal parameter types of the constructor.
  93      * Returns an empty array if the constructor takes no parameters.
  94      *
  95      * @param constructor  the object that represents constructor
  96      * @return the parameter types of the constructor
  97      */
  98     @Override
  99     protected Class<?>[] getParameters(Constructor<?> constructor) {
 100         return constructor.getParameterTypes();
 101     }
 102 
 103     /**
 104      * Returns {@code true} if and only if the constructor
 105      * was declared to take a variable number of arguments.
 106      *
 107      * @param constructor  the object that represents constructor
 108      * @return {@code true} if the constructor was declared
 109      *         to take a variable number of arguments;
 110      *         {@code false} otherwise
 111      */
 112     @Override
 113     protected boolean isVarArgs(Constructor<?> constructor) {
 114         return constructor.isVarArgs();
 115     }
 116 
 117     /**
 118      * Checks validness of the constructor.
 119      * The valid constructor should be public.
 120      *
 121      * @param constructor  the object that represents constructor
 122      * @return {@code true} if the constructor is valid,
 123      *         {@code false} otherwise
 124      */
 125     @Override
 126     protected boolean isValid(Constructor<?> constructor) {
 127         return Modifier.isPublic(constructor.getModifiers());
 128     }
 129 }