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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.configuration.beanutils;
18  
19  import java.util.Map;
20  
21  /***
22   * <p>
23   * Definition of an interface for declaring a bean in a configuration file.
24   * </p>
25   * <p>
26   * Commons Configurations allows to define beans (i.e. simple Java objects) in
27   * configuration files, which can be created at runtime. This is especially
28   * useful if you program against interfaces and want to define the concrete
29   * implementation class is a configuration file.
30   * </p>
31   * <p>
32   * This interface defines methods for retrieving all information about a bean
33   * that should be created from a configuration file, e.g. the bean's properties
34   * or the factory to use for creating the instance. With different
35   * implementations different &quot;layouts&quot; of bean declarations can be
36   * supported. For instance if an XML configuration file is used, all features of
37   * XML (e.g. attributes, nested elements) can be used to define the bean. In a
38   * properties file the declaration format is more limited. The purpose of this
39   * interface is to abstract from the concrete declaration format.
40   * </p>
41   *
42   * @since 1.3
43   * @author Oliver Heger
44   * @version $Id: BeanDeclaration.java 439648 2006-09-02 20:42:10Z oheger $
45   */
46  public interface BeanDeclaration
47  {
48      /***
49       * Returns the name of the <code>BeanFactory</code> that should be used
50       * for creating the bean instance. This can be <b>null</b>, then a default
51       * factory will be used.
52       *
53       * @return the name of the bean factory
54       */
55      String getBeanFactoryName();
56  
57      /***
58       * Here an arbitrary object can be returned that will be passed to the bean
59       * factory. Its meaning is not further specified. The purpose of this
60       * additional parameter is to support a further configuration of the bean
61       * factory that can be placed directly at the bean declaration.
62       *
63       * @return a parameter for the bean factory
64       */
65      Object getBeanFactoryParameter();
66  
67      /***
68       * Returns the name of the bean class, from which an instance is to be
69       * created. This value must be defined unless a default class is provided
70       * for the bean creation operation.
71       *
72       * @return the name of the bean class
73       */
74      String getBeanClassName();
75  
76      /***
77       * Returns a map with properties that should be initialized on the newly
78       * created bean. The map's keys are the names of the properties; the
79       * corresponding values are the properties' values. The return value can be
80       * <b>null</b> if no properties should be set.
81       *
82       * @return a map with properties to be initialized
83       */
84      Map getBeanProperties();
85  
86      /***
87       * Returns a map with declarations for beans that should be set as
88       * properties of the newly created bean. This allows for complex
89       * initialization szenarios: a bean for a bean that contains complex
90       * properties (e.g. other beans) can have nested declarations for defining
91       * these complex properties. The returned map's key are the names of the
92       * properties to initialze. The values are <code>BeanDeclaration</code>
93       * implementations. They will be treated like this declaration (in a
94       * recursive manner), and the resulting beans are assigned to the
95       * corresponding properties.
96       *
97       * @return a map with nested bean declarations
98       */
99      Map getNestedBeanDeclarations();
100 }