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Java > Open Source Codes > com > go > trove > util > DelegateClassLoader


1 /* ====================================================================
2  * Trove - Copyright (c) 1997-2000 Walt Disney Internet Group
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4  * The Tea Software License, Version 1.1
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52
53 package com.go.trove.util;
54 import java.io.InputStream JavaDoc;
55 import java.net.URL JavaDoc;
56
57 /******************************************************************************
58  * ClassLoader that delegates class loading requests if the parent ClassLoader
59  * (and its ancestors) can't fulfill the request. Class loading requests are
60  * handed off to scouts, which are called upon in sequence to find the class,
61  * until the class is found. If neither the parent or scouts can find a
62  * requested class, a normal ClassNotFoundException is thrown.
63  *
64  * @author Brian S O'Neill
65  * @version
66  * <!--$$Revision:--> 14 <!-- $-->, <!--$$JustDate:--> 7/27/01 <!-- $-->
67  */
68 public class DelegateClassLoader extends ClassLoader JavaDoc {
69     private ClassLoader JavaDoc[] mScouts;
70
71     /**
72      * @param parent ClassLoader that gets first chance to load a class
73      * @param scouts ClassLoaders that get next chances to load a class, if the
74      * parent couldn't find it.
75      */
76     public DelegateClassLoader(ClassLoader JavaDoc parent, ClassLoader JavaDoc[] scouts) {
77         super(parent);
78         mScouts = (ClassLoader JavaDoc[])scouts.clone();
79    }
80
81     /**
82      * @param scouts ClassLoaders that get next chances to load a class, if the
83      * parent couldn't find it.
84      * @deprecated Actual parent ClassLoader must always be provided to prevent
85      * unexpected behavior.
86      */
87     public DelegateClassLoader(ClassLoader JavaDoc[] scouts) {
88         super();
89         mScouts = (ClassLoader JavaDoc[])scouts.clone();
90     }
91
92     protected synchronized Class JavaDoc findClass(String JavaDoc name)
93         throws ClassNotFoundException JavaDoc
94     {
95         for (int i=0; i<mScouts.length; i++) {
96             try {
97                 return mScouts[i].loadClass(name);
98             }
99             catch (ClassNotFoundException JavaDoc e) {
100             }
101         }
102         throw new ClassNotFoundException JavaDoc(name);
103     }
104     
105     protected URL JavaDoc findResource(String JavaDoc name) {
106         URL JavaDoc resource = null;
107
108         try {
109             for (int i=0; i<mScouts.length; i++) {
110                 resource = mScouts[i].getResource(name);
111                 if (resource != null) {
112                     return resource;
113                 }
114             }
115         }
116         catch (Exception JavaDoc e) {
117             e.printStackTrace();
118         }
119         return resource;
120     }
121 }
122
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