ContainerSuppliedMixinFactory


1   /*****************************************************************************
2    * Copyright (c) PicoContainer Organization. All rights reserved.            *
3    * ------------------------------------------------------------------------- *
4    * The software in this package is published under the terms of the BSD      *
5    * style license a copy of which has been included with this distribution in *
6    * the LICENSE.txt file.                                                     *
7    *                                                                           *
8    * Idea by Rachel Davies, Original code by various                           *
9    *****************************************************************************/
10  package org.nanocontainer.aop.dynaop;
11  
12  import dynaop.MixinFactory;
13  import dynaop.Proxy;
14  import org.picocontainer.ComponentAdapter;
15  import org.picocontainer.PicoContainer;
16  import org.picocontainer.defaults.ConstructorInjectionComponentAdapter;
17  
18  import java.util.Properties  ;
19  
20  /**
21   * Manufactures mixins from a <code>PicoContainer</code>. Useful when a mixin
22   * has dependencies on other components in the <code>PicoContainer</code>.
23   *
24   * @author Stephen Molitor
25   * @version $Revision: 3144 $
26   */
27  class ContainerSuppliedMixinFactory implements MixinFactory {
28  
29      private final PicoContainer pico;
30      private final Class   mixinClass;
31  
32      /**
33       * Creates a new <code>ContainerSuppliedMixinFactory</code> that will
34       * manufacture mixins by retrieving them from the <code>PicoContainer</code>
35       * using a given component key.
36       *
37       * @param pico              the <code>PicoContainer</code> to retrieve the mixin from.
38       * @param mixinComponentKey the component key that will be used to retrieve
39       *                          the mixin object from the pico container.
40       */
41      ContainerSuppliedMixinFactory(PicoContainer pico, Class   mixinClass) {
42          this.pico = pico;
43          this.mixinClass = mixinClass;
44      }
45  
46      /**
47       * Manufactures a <code>Mixin</code> by retrieving it from the
48       * <code>PicoContainer</code>.
49       *
50       * @param proxy the proxy that the interceptor will wrap.
51       * @return the <code>Mixin</code> object.
52       * @throws NullPointerException if the mixin can not be found in the pico
53       *                              container.
54       */
55      public Object   create(Proxy proxy) throws NullPointerException   {
56          Object   mixin = pico.getComponentInstanceOfType(mixinClass);
57          if (mixin == null) {
58              ComponentAdapter adapter = new ConstructorInjectionComponentAdapter(mixinClass, mixinClass);
59              mixin = adapter.getComponentInstance(pico);
60          }
61          return mixin;
62      }
63  
64      /**
65       * Gets properties. Useful for debugging.
66       *
67       * @return an empty <code>Properties</code> object.
68       */
69      public Properties   getProperties() {
70          Properties   properties = new Properties  ();
71          properties.setProperty("advice", "mixin");
72          return properties;
73      }
74  
75  }
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