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 import java.util.Map;
020
021 /**
022 * <p>
023 * Definition of an interface for declaring a bean in a configuration file.
024 * </p>
025 * <p>
026 * Commons Configurations allows to define beans (i.e. simple Java objects) in
027 * configuration files, which can be created at runtime. This is especially
028 * 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
033 * that should be created from a configuration file, e.g. the bean's properties
034 * or the factory to use for creating the instance. With different
035 * implementations different "layouts" of bean declarations can be
036 * supported. For instance if an XML configuration file is used, all features of
037 * XML (e.g. attributes, nested elements) can be used to define the bean. In a
038 * properties file the declaration format is more limited. The purpose of this
039 * interface is to abstract from the concrete declaration format.
040 * </p>
041 *
042 * @since 1.3
043 * @author Oliver Heger
044 * @version $Id: BeanDeclaration.java 439648 2006-09-02 20:42:10Z oheger $
045 */
046 public interface BeanDeclaration
047 {
048 /**
049 * Returns the name of the <code>BeanFactory</code> that should be used
050 * for creating the bean instance. This can be <b>null</b>, then a default
051 * factory will be used.
052 *
053 * @return the name of the bean factory
054 */
055 String getBeanFactoryName();
056
057 /**
058 * Here an arbitrary object can be returned that will be passed to the bean
059 * factory. Its meaning is not further specified. The purpose of this
060 * additional parameter is to support a further configuration of the bean
061 * factory that can be placed directly at the bean declaration.
062 *
063 * @return a parameter for the bean factory
064 */
065 Object getBeanFactoryParameter();
066
067 /**
068 * Returns the name of the bean class, from which an instance is to be
069 * created. This value must be defined unless a default class is provided
070 * for the bean creation operation.
071 *
072 * @return the name of the bean class
073 */
074 String getBeanClassName();
075
076 /**
077 * Returns a map with properties that should be initialized on the newly
078 * created bean. The map's keys are the names of the properties; the
079 * corresponding values are the properties' values. The return value can be
080 * <b>null</b> if no properties should be set.
081 *
082 * @return a map with properties to be initialized
083 */
084 Map getBeanProperties();
085
086 /**
087 * Returns a map with declarations for beans that should be set as
088 * properties of the newly created bean. This allows for complex
089 * initialization szenarios: a bean for a bean that contains complex
090 * properties (e.g. other beans) can have nested declarations for defining
091 * these complex properties. The returned map's key are the names of the
092 * properties to initialze. The values are <code>BeanDeclaration</code>
093 * implementations. They will be treated like this declaration (in a
094 * recursive manner), and the resulting beans are assigned to the
095 * corresponding properties.
096 *
097 * @return a map with nested bean declarations
098 */
099 Map getNestedBeanDeclarations();
100 }