001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.jocl;
019
020 import java.lang.reflect.Constructor;
021 import java.lang.reflect.InvocationTargetException;
022
023 /**
024 * Miscellaneous {@link Constructor} related utility functions.
025 *
026 * @author Rodney Waldhoff
027 * @version $Revision: 479137 $ $Date: 2006-11-25 10:51:48 -0500 (Sat, 25 Nov 2006) $
028 */
029 public class ConstructorUtil {
030 /**
031 * Returns a {@link Constructor} for the given method signature, or <tt>null</tt>
032 * if no such <tt>Constructor</tt> can be found.
033 *
034 * @param type the (non-<tt>null</tt>) type of {@link Object} the returned {@link Constructor} should create
035 * @param argTypes a non-<tt>null</tt> array of types describing the parameters to the {@link Constructor}.
036 * @return a {@link Constructor} for the given method signature, or <tt>null</tt>
037 * if no such <tt>Constructor</tt> can be found.
038 * @see #invokeConstructor
039 */
040 public static Constructor getConstructor(Class type, Class[] argTypes) {
041 if(null == type || null == argTypes) {
042 throw new NullPointerException();
043 }
044 Constructor ctor = null;
045 try {
046 ctor = type.getConstructor(argTypes);
047 } catch(Exception e) {
048 ctor = null;
049 }
050 if(null == ctor) {
051 // no directly declared matching constructor,
052 // look for something that will work
053 // XXX this should really be more careful to
054 // adhere to the jls mechanism for late binding
055 Constructor[] ctors = type.getConstructors();
056 for(int i=0;i<ctors.length;i++) {
057 Class[] paramtypes = ctors[i].getParameterTypes();
058 if(paramtypes.length == argTypes.length) {
059 boolean canuse = true;
060 for(int j=0;j<paramtypes.length;j++) {
061 if(paramtypes[j].isAssignableFrom(argTypes[j])) {
062 continue;
063 } else {
064 canuse = false;
065 break;
066 }
067 }
068 if(canuse == true) {
069 ctor = ctors[i];
070 break;
071 }
072 }
073 }
074 }
075 return ctor;
076 }
077
078 /**
079 * Creates a new instance of the specified <tt><i>type</i></tt>
080 * using a {@link Constructor} described by the given parameter types
081 * and values.
082 *
083 * @param type the type of {@link Object} to be created
084 * @param argTypes a non-<tt>null</tt> array of types describing the parameters to the {@link Constructor}.
085 * @param argValues a non-<tt>null</tt> array containing the values of the parameters to the {@link Constructor}.
086 * @return a new instance of the specified <tt><i>type</i></tt>
087 * using a {@link Constructor} described by the given parameter types
088 * and values.
089 * @exception InstantiationException
090 * @exception IllegalAccessException
091 * @exception InvocationTargetException
092 */
093 public static Object invokeConstructor(Class type, Class[] argTypes, Object[] argValues) throws InstantiationException, IllegalAccessException, InvocationTargetException {
094 return ConstructorUtil.getConstructor(type,argTypes).newInstance(argValues);
095 }
096 }
097
098