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 package org.apache.commons.configuration.beanutils; 018 019 /** 020 * <p> 021 * The default implementation of the <code>BeanFactory</code> interface. 022 * </p> 023 * <p> 024 * This class creates beans of arbitrary types using reflection. Each time the 025 * <code>createBean()</code> method is invoked, a new bean instance is 026 * created. A default bean class is not supported. 027 * </p> 028 * <p> 029 * An instance of this factory class will be set as the default bean factory for 030 * the <code>{@link BeanHelper}</code> class. This means that if not bean 031 * factory is specified in a <code>{@link BeanDeclaration}</code>, this 032 * default instance will be used. 033 * </p> 034 * 035 * @since 1.3 036 * @author Oliver Heger 037 * @version $Id: DefaultBeanFactory.java 439648 2006-09-02 20:42:10Z oheger $ 038 */ 039 public class DefaultBeanFactory implements BeanFactory 040 { 041 /** Stores the default instance of this class. */ 042 public static final DefaultBeanFactory INSTANCE = new DefaultBeanFactory(); 043 044 /** 045 * Creates a new bean instance. This implementation delegates to the 046 * protected methods <code>createBeanInstance()</code> and 047 * <code>initBeanInstance()</code> for creating and initializing the bean. 048 * This makes it easier for derived classes that need to change specific 049 * functionality of the base class. 050 * 051 * @param beanClass the class of the bean, from which an instance is to be 052 * created 053 * @param data the bean declaration object 054 * @param parameter an additional parameter (ignored by this implementation) 055 * @return the new bean instance 056 * @throws Exception if an error occurs 057 */ 058 public Object createBean(Class beanClass, BeanDeclaration data, 059 Object parameter) throws Exception 060 { 061 Object result = createBeanInstance(beanClass, data); 062 initBeanInstance(result, data); 063 return result; 064 } 065 066 /** 067 * Returns the default bean class used by this factory. This is always 068 * <b>null</b> for this implementation. 069 * 070 * @return the default bean class 071 */ 072 public Class getDefaultBeanClass() 073 { 074 return null; 075 } 076 077 /** 078 * Creates the bean instance. This method is called by 079 * <code>createBean()</code>. It uses reflection to create a new instance 080 * of the specified class. 081 * 082 * @param beanClass the class of the bean to be created 083 * @param data the bean declaration 084 * @return the new bean instance 085 * @throws Exception if an error occurs 086 */ 087 protected Object createBeanInstance(Class beanClass, BeanDeclaration data) 088 throws Exception 089 { 090 return beanClass.newInstance(); 091 } 092 093 /** 094 * Initializes the newly created bean instance. This method is called by 095 * <code>createBean()</code>. It calls the 096 * <code>{@link BeanHelper#initBean(Object, BeanDeclaration) initBean()}</code> 097 * of <code>{@link BeanHelper}</code> for performing the initialization. 098 * 099 * @param bean the newly created bean instance 100 * @param data the bean declaration object 101 * @throws Exception if an error occurs 102 */ 103 protected void initBeanInstance(Object bean, BeanDeclaration data) 104 throws Exception 105 { 106 BeanHelper.initBean(bean, data); 107 } 108 }