Runtime


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4   * by the @authors tag. See the copyright.txt in the distribution for a
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8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10  * the License, or (at your option) any later version.
11  *
12  * This software is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this software; if not, write to the Free
19  * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20  * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21  */
22  package org.jboss.proxy.compiler;
23  
24  import java.lang.reflect.Method  ;
25  import java.lang.reflect.Field  ;
26  
27  import java.io.InputStream  ;
28  
29  import java.net.URL  ;
30  import java.security.PrivilegedAction  ;
31  import java.security.AccessController  ;
32  
33  /**
34   * Manages bytecode assembly for dynamic proxy generation.
35   * <p/>
36   * <p>This is the only data needed at runtime.
37   *
38   * @author Unknown
39   * @author <a HREF="mailto:jason@planet57.com">Jason Dillon</a>
40   * @version <tt>$Revision: 37459 $</tt>
41   */
42  public class Runtime
43     extends ClassLoader  
44  {
45     /**
46      * The field name of the runtime target proxies Runtime object.
47      */
48     public final static String   RUNTIME_FN = "runtime";
49  
50     /**
51      * Construct a new <tt>Runtime</tt>
52      *
53      * @param parent The parent classloader to delegate to.
54      */
55     public Runtime(ClassLoader   parent)
56     {
57        super(parent);
58     }
59  
60     // These members are common utilities used by ProxyTarget classes.
61     // They are all public so they can be linked to from generated code.
62     // I.e., they are the runtime support for the code compiled below.
63  
64     Class   targetTypes[];
65     Method   methods[];
66     ProxyCompiler compiler;// temporary!
67  
68     public Class  [] copyTargetTypes()
69     {
70        return (Class  []) targetTypes.clone();
71     }
72  
73     public Object   invoke(InvocationHandler invocationHandler, int methodNum, Object   values[])
74        throws Throwable  
75     {
76        return invocationHandler.invoke(null, methods[methodNum], values);
77     }
78  
79     void makeProxyType(ProxyCompiler compiler)
80        throws Exception  
81     {
82        this.compiler = compiler; // temporary, for use during loading
83        byte code[] = compiler.getCode();
84  
85        compiler.proxyType = super.defineClass(compiler.getProxyClassName(), code, 0, code.length);
86        super.resolveClass(compiler.proxyType);
87  
88        // set the Foo$Impl.info pointer to myself
89        Field   field = compiler.proxyType.getField(RUNTIME_FN);
90        field.set(null, this);
91  
92        compiler = null;
93     }
94  
95     ClassLoader   getTargetClassLoader()
96     {
97        PrivilegedAction   action = new PrivilegedAction  ()
98        {
99           public Object   run()
100          {
101             return getParent();
102          }
103       };
104       return (ClassLoader  ) AccessController.doPrivileged(action);
105    }
106 
107    public synchronized Class   loadClass(String   name, boolean resolve)
108       throws ClassNotFoundException  
109    {
110       // isn't this redundant?
111       if (name.endsWith("$Proxy") && name.equals(compiler.getProxyClassName()))
112       {
113          return compiler.proxyType;
114       }
115 
116       // delegate to the original class loader
117       ClassLoader   cl = getTargetClassLoader();
118       if (cl == null)
119       {
120          return super.findSystemClass(name);
121       }
122 
123       return cl.loadClass(name);
124    }
125 
126    /**
127     * Delegate to the original class loader.
128     */
129    public InputStream   getResourceAsStream(String   name)
130    {
131       ClassLoader   cl = getTargetClassLoader();
132 
133       if (cl == null)
134       {
135          return super.getSystemResourceAsStream(name);
136       }
137 
138       return cl.getResourceAsStream(name);
139    }
140 
141    /**
142     * Delegate to the original class loader.
143     */
144    public URL   getResource(String   name)
145    {
146       ClassLoader   cl = getTargetClassLoader();
147 
148       if (cl == null)
149       {
150          return super.getSystemResource(name);
151       }
152 
153       return cl.getResource(name);
154    }
155 }
156
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