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