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Java > Open Source Codes > org > openejb > client > proxy > Jdk13InvocationHandler


1 /**
2  * Redistribution and use of this software and associated documentation
3  * ("Software"), with or without modification, are permitted provided
4  * that the following conditions are met:
5  *
6  * 1. Redistributions of source code must retain copyright
7  * statements and notices. Redistributions must also contain a
8  * copy of this document.
9  *
10  * 2. Redistributions in binary form must reproduce the
11  * above copyright notice, this list of conditions and the
12  * following disclaimer in the documentation and/or other
13  * materials provided with the distribution.
14  *
15  * 3. The name "OpenEJB" must not be used to endorse or promote
16  * products derived from this Software without prior written
17  * permission of The OpenEJB Group. For written permission,
18  * please contact dev@openejb.org.
19  *
20  * 4. Products derived from this Software may not be called "OpenEJB"
21  * nor may "OpenEJB" appear in their names without prior written
22  * permission of The OpenEJB Group. OpenEJB is a registered
23  * trademark of The OpenEJB Group.
24  *
25  * 5. Due credit should be given to the OpenEJB Project
26  * (http://www.openejb.org/).
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE OPENEJB GROUP AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32  * THE OPENEJB GROUP OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39  * OF THE POSSIBILITY OF SUCH DAMAGE.
40  *
41  * Copyright 2001 (C) The OpenEJB Group. All Rights Reserved.
42  *
43  * $Id: Jdk13InvocationHandler.java 1921 2005-06-19 22:40:34Z jlaskowski $
44  */
45 package org.openejb.client.proxy;
46
47 import java.io.Serializable JavaDoc;
48 import java.lang.reflect.Method JavaDoc;
49
50 /**
51  * Implementation of JDK 1.3 InvocationHandler for JDK 1.3 Proxies.
52  * This only compiles on JDK 1.3 or better. This is the interface
53  * between the OpenEJB InvocationHandler and the JDK 1.3 proxy. It
54  * allows the OpenEJB InvocationHandler to be null or changed after
55  * proxy instantiation, which is not normally allowed for JDK 1.3
56  * proxies.
57  *
58  * @author Aaron Mulder (ammulder@alumni.princeton.edu)
59  */
60 public class Jdk13InvocationHandler implements java.lang.reflect.InvocationHandler JavaDoc, Serializable JavaDoc {
61     
62     /**
63      * The InvocationHandler that will receive all the calls on the proxy
64      */
65     private InvocationHandler delegate;
66
67     /**
68      * Constructs a new JDK 1.3 compatable InvocationHandler that delegates
69      * all invocations to an OpenEJB invocation handler.
70      */
71     public Jdk13InvocationHandler() {
72     }
73
74     /**
75      *
76      * Constructs a new JDK 1.3 compatable InvocationHandler that delegates
77      * all invocations to an OpenEJB invocation handler.
78      *
79      * @param delegate
80      */
81     public Jdk13InvocationHandler(InvocationHandler delegate) {
82         setInvocationHandler(delegate);
83     }
84
85     /**
86      * Returns the InvocationHandler that will receive all the calls on the proxy
87      *
88      * @return InvocationHandler
89      */
90     public InvocationHandler getInvocationHandler() {
91         return delegate;
92     }
93
94     /**
95      * Sets the InvocationHandler that will receive all the calls on the proxy
96      *
97      * @param handler
98      * @return InvocationHandler
99      */
100     public InvocationHandler setInvocationHandler(InvocationHandler handler) {
101         InvocationHandler old = delegate;
102         delegate = handler;
103         return old;
104     }
105
106     /**
107      * Invoked by the proxy instance when one of its methods have been called.
108      * The invocation is delegated to the OpenEJB invocation handler.
109      *
110      * @param proxy
111      * @param method
112      * @param args
113      * @return Object
114      * @exception Throwable
115      */
116     public Object JavaDoc invoke(Object JavaDoc proxy, Method JavaDoc method, Object JavaDoc[] args) throws Throwable JavaDoc {
117         
118         if ( delegate == null ) throw new NullPointerException JavaDoc("No invocation handler for proxy "+proxy);
119         
120         if(args == null) {
121             args = new Object JavaDoc[0];
122             // A bug in the proxy call?
123 }
124         
125         return delegate.invoke(proxy, method, args);
126     }
127 }
128
129
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