ContainerSuppliedInterceptorFactory


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.Interceptor;
13  import dynaop.InterceptorFactory;
14  import dynaop.Proxy;
15  import org.aopalliance.intercept.MethodInterceptor;
16  import org.picocontainer.PicoContainer;
17  
18  import java.util.Properties  ;
19  
20  /**
21   * Manufactures interceptors from a <code>PicoContainer</code>. Useful when
22   * an interceptor has dependencies on other components in the
23   * <code>PicoContainer</code>.
24   *
25   * @author Stephen Molitor
26   * @version $Revision: 3144 $
27   */
28  class ContainerSuppliedInterceptorFactory implements InterceptorFactory {
29  
30      private final PicoContainer pico;
31      private final Object   interceptorComponentKey;
32  
33      /**
34       * Creates a new <code>ContainerSuppliedInterceptorFactory</code> that
35       * will manufacture interceptors by retrieving them from the
36       * <code>PicoContainer</code> using a given component key.
37       *
38       * @param pico                    the <code>PicoContainer</code> to retrieve the interceptor
39       *                                from.
40       * @param interceptorComponentKey the component key that will be used to
41       *                                retrieve the interceptor from the pico container.
42       */
43      ContainerSuppliedInterceptorFactory(PicoContainer pico, Object   interceptorComponentKey) {
44          this.pico = pico;
45          this.interceptorComponentKey = interceptorComponentKey;
46      }
47  
48      /**
49       * Manufactures an <code>Interceptor</code> by retrieving it from the
50       * <code>PicoContainer</code>.
51       *
52       * @param proxy not used.
53       * @return the <code>Interceptor</code> object.
54       * @throws NullPointerException if the interceptor can not be found in the
55       *                              pico container.
56       */
57      public Interceptor create(Proxy proxy) throws NullPointerException   {
58          MethodInterceptor methodInterceptor = (MethodInterceptor) pico.getComponentInstance(interceptorComponentKey);
59          if (methodInterceptor == null) {
60              throw new NullPointerException  ("Interceptor with component key " + interceptorComponentKey
61                      + " + not found in PicoContainer");
62          }
63          return new MethodInterceptorAdapter(methodInterceptor);
64      }
65  
66      /**
67       * Gets properties. Useful for debugging.
68       *
69       * @return a <code>Properties</code> object.
70       */
71      public Properties   getProperties() {
72          Properties   properties = new Properties  ();
73          properties.setProperty("advice", "method interceptor");
74          properties.setProperty("scope", "per-instance");
75          return properties;
76      }
77  
78  }
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