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 }