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1   /*** 
2    * 
3    * Copyright 2004 Protique Ltd
4    * 
5    * Licensed under the Apache License, Version 2.0 (the "License"); 
6    * you may not use this file except in compliance with the License. 
7    * You may obtain a copy of the License at 
8    * 
9    * http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS, 
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
14   * See the License for the specific language governing permissions and 
15   * limitations under the License. 
16   * 
17   **/
18  
19  package org.codehaus.activemq.util;
20  
21  import EDU.oswego.cs.dl.util.concurrent.Executor;
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  
25  import java.lang.reflect.InvocationHandler;
26  import java.lang.reflect.Method;
27  import java.lang.reflect.Proxy;
28  
29  /***
30   * A proxy to some service which offers an asynchronous way to invoke methods which
31   * are void and don't throw exceptions. Calling the method results in a command object
32   * being added to a queue for later execution.
33   *
34   * @version $Revision: 1.1 $
35   */
36  public class AsyncProxy implements InvocationHandler {
37  
38      private Object realObject;
39      private Executor executor;
40      private Log log;
41  
42      public static Object createProxy(Class interfaceType, Object realObject, Executor executor) {
43          return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
44                  new Class[]{interfaceType},
45                  new AsyncProxy(realObject, executor));
46      }
47  
48      public AsyncProxy(Object realObject, Executor executor) {
49          this(realObject, executor, LogFactory.getLog(AsyncProxy.class));
50      }
51  
52      public AsyncProxy(Object realObject, Executor executor, Log log) {
53          this.realObject = realObject;
54          this.executor = executor;
55          this.log = log;
56      }
57  
58      public AsyncProxy(Executor executor, Log log) {
59          this.executor = executor;
60          this.log = log;
61      }
62  
63      public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
64          if (method.getReturnType() == void.class) {
65              executor.execute(new Runnable() {
66                  public void run() {
67                      doAsyncMethodInvoke(method, args);
68                  }
69              });
70              return null;
71          }
72          else {
73              return method.invoke(realObject, args);
74          }
75      }
76  
77      protected void doAsyncMethodInvoke(Method method, Object[] args) {
78          try {
79              method.invoke(realObject, args);
80          }
81          catch (Throwable e) {
82              log.warn("Caught exception: " + e, e);
83          }
84      }
85  }