1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. 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 package org.apache.commons.proxy.interceptor;
19
20 import EDU.oswego.cs.dl.util.concurrent.Executor;
21 import org.apache.commons.proxy.Interceptor;
22 import org.apache.commons.proxy.Invocation;
23
24 /**
25 * A method interceptor that uses an {@link Executor} to execute the method invocation.
26 * <p/>
27 * <b>Note</b>: Only <em>void</em> methods can be intercepted using this class! Any attempts to intercept non-void
28 * methods will result in an {@link IllegalArgumentException}. If the proxy interfaces include non-void methods, try
29 * using a {@link FilteredInterceptor} along with a
30 * {@link org.apache.commons.proxy.interceptor.filter.ReturnTypeFilter} to wrap an instance of this class.
31 * <p/>
32 * <p>
33 * <b>Dependencies</b>:
34 * <ul>
35 * <li>Concurrent API version 1.3.4 or greater</li>
36 * </ul>
37 * </p>
38 *
39 * @author James Carman
40 * @since 1.0
41 */
42 public class ExecutorInterceptor implements Interceptor
43 {
44 //**********************************************************************************************************************
45 // Fields
46 //**********************************************************************************************************************
47
48 private final Executor executor;
49
50 //**********************************************************************************************************************
51 // Constructors
52 //**********************************************************************************************************************
53
54 public ExecutorInterceptor( Executor executor )
55 {
56 this.executor = executor;
57 }
58
59 //**********************************************************************************************************************
60 // Interceptor Implementation
61 //**********************************************************************************************************************
62
63
64 public Object intercept( final Invocation invocation ) throws Throwable
65 {
66 if( Void.TYPE.equals(invocation.getMethod().getReturnType()) )
67 {
68 // Special case for finalize() method (should not be run in a different thread)...
69 if( !( invocation.getMethod().getName().equals("finalize") &&
70 invocation.getMethod().getParameterTypes().length == 0 ) )
71 {
72 executor.execute(new Runnable()
73 {
74 public void run()
75 {
76 try
77 {
78 invocation.proceed();
79 }
80 catch( Throwable t )
81 {
82 // What to do here? I can't convey the failure back to the caller.
83 }
84 }
85 });
86 return null;
87 }
88 else
89 {
90 return invocation.proceed();
91 }
92 }
93 else
94 {
95 throw new IllegalArgumentException("Only void methods can be executed in a different thread.");
96 }
97 }
98 }