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17 package org.apache.commons.configuration.beanutils;
18
19 /***
20 * <p>
21 * The default implementation of the <code>BeanFactory</code> interface.
22 * </p>
23 * <p>
24 * This class creates beans of arbitrary types using reflection. Each time the
25 * <code>createBean()</code> method is invoked, a new bean instance is
26 * created. A default bean class is not supported.
27 * </p>
28 * <p>
29 * An instance of this factory class will be set as the default bean factory for
30 * the <code>{@link BeanHelper}</code> class. This means that if not bean
31 * factory is specified in a <code>{@link BeanDeclaration}</code>, this
32 * default instance will be used.
33 * </p>
34 *
35 * @since 1.3
36 * @author Oliver Heger
37 * @version $Id: DefaultBeanFactory.java 439648 2006-09-02 20:42:10Z oheger $
38 */
39 public class DefaultBeanFactory implements BeanFactory
40 {
41 /*** Stores the default instance of this class. */
42 public static final DefaultBeanFactory INSTANCE = new DefaultBeanFactory();
43
44 /***
45 * Creates a new bean instance. This implementation delegates to the
46 * protected methods <code>createBeanInstance()</code> and
47 * <code>initBeanInstance()</code> for creating and initializing the bean.
48 * This makes it easier for derived classes that need to change specific
49 * functionality of the base class.
50 *
51 * @param beanClass the class of the bean, from which an instance is to be
52 * created
53 * @param data the bean declaration object
54 * @param parameter an additional parameter (ignored by this implementation)
55 * @return the new bean instance
56 * @throws Exception if an error occurs
57 */
58 public Object createBean(Class beanClass, BeanDeclaration data,
59 Object parameter) throws Exception
60 {
61 Object result = createBeanInstance(beanClass, data);
62 initBeanInstance(result, data);
63 return result;
64 }
65
66 /***
67 * Returns the default bean class used by this factory. This is always
68 * <b>null</b> for this implementation.
69 *
70 * @return the default bean class
71 */
72 public Class getDefaultBeanClass()
73 {
74 return null;
75 }
76
77 /***
78 * Creates the bean instance. This method is called by
79 * <code>createBean()</code>. It uses reflection to create a new instance
80 * of the specified class.
81 *
82 * @param beanClass the class of the bean to be created
83 * @param data the bean declaration
84 * @return the new bean instance
85 * @throws Exception if an error occurs
86 */
87 protected Object createBeanInstance(Class beanClass, BeanDeclaration data)
88 throws Exception
89 {
90 return beanClass.newInstance();
91 }
92
93 /***
94 * Initializes the newly created bean instance. This method is called by
95 * <code>createBean()</code>. It calls the
96 * <code>{@link BeanHelper#initBean(Object, BeanDeclaration) initBean()}</code>
97 * of <code>{@link BeanHelper}</code> for performing the initialization.
98 *
99 * @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 }