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 */ 017package org.apache.commons.configuration2.beanutils; 018 019import java.util.Collection; 020import java.util.Map; 021 022/** 023 * <p> 024 * Definition of an interface for declaring a bean in a configuration file. 025 * </p> 026 * <p> 027 * Commons Configurations allows to define beans (i.e. simple Java objects) in 028 * configuration files, which can be created at runtime. This is especially 029 * useful if you program against interfaces and want to define the concrete 030 * implementation class is a configuration file. 031 * </p> 032 * <p> 033 * This interface defines methods for retrieving all information about a bean 034 * that should be created from a configuration file, e.g. the bean's properties 035 * or the factory to use for creating the instance. With different 036 * implementations different "layouts" of bean declarations can be 037 * supported. For instance if an XML configuration file is used, all features of 038 * XML (e.g. attributes, nested elements) can be used to define the bean. In a 039 * properties file the declaration format is more limited. The purpose of this 040 * interface is to abstract from the concrete declaration format. 041 * </p> 042 * 043 * @since 1.3 044 */ 045public interface BeanDeclaration 046{ 047 /** 048 * Returns the name of the {@code BeanFactory} that should be used 049 * for creating the bean instance. This can be <b>null</b>, then a default 050 * factory will be used. 051 * 052 * @return the name of the bean factory 053 */ 054 String getBeanFactoryName(); 055 056 /** 057 * Here an arbitrary object can be returned that will be passed to the bean 058 * factory. Its meaning is not further specified. The purpose of this 059 * additional parameter is to support a further configuration of the bean 060 * factory that can be placed directly at the bean declaration. 061 * 062 * @return a parameter for the bean factory 063 */ 064 Object getBeanFactoryParameter(); 065 066 /** 067 * Returns the name of the bean class, from which an instance is to be 068 * created. This value must be defined unless a default class is provided 069 * for the bean creation operation. 070 * 071 * @return the name of the bean class 072 */ 073 String getBeanClassName(); 074 075 /** 076 * Returns a map with properties that should be initialized on the newly 077 * created bean. The map's keys are the names of the properties; the 078 * corresponding values are the properties' values. The return value can be 079 * <b>null</b> if no properties should be set. 080 * 081 * @return a map with properties to be initialized 082 */ 083 Map<String, Object> getBeanProperties(); 084 085 /** 086 * Returns a map with declarations for beans that should be set as 087 * properties of the newly created bean. This allows for complex 088 * initialization scenarios: a bean for a bean that contains complex 089 * properties (e.g. other beans) can have nested declarations for defining 090 * these complex properties. The returned map's key are the names of the 091 * properties to initialize. The values are either {@code BeanDeclaration} 092 * implementations or collections thereof. They will be treated like this 093 * declaration (in a recursive manner), and the resulting beans are 094 * assigned to the corresponding properties. 095 * 096 * @return a map with nested bean declarations 097 */ 098 Map<String, Object> getNestedBeanDeclarations(); 099 100 /** 101 * Returns a collection with constructor arguments. This data is used to 102 * determine the constructor of the bean class to be invoked. The values of 103 * the arguments are passed to the constructor. An implementation can return 104 * <b>null</b> or an empty collection; then the standard constructor of the 105 * bean class is called. 106 * 107 * @return a collection with the arguments to be passed to the bean class's 108 * constructor 109 */ 110 Collection<ConstructorArg> getConstructorArgs(); 111}