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.Invocation;
22 import org.apache.commons.proxy.Interceptor;
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 *
32 * <p>
33 * <b>Dependencies</b>:
34 * <ul>
35 * <li>Concurrent API version 1.3.4 or greater</li>
36 * </ul>
37 * </p>
38 * @author James Carman
39 * @since 1.0
40 */
41 public class ExecutorInterceptor implements Interceptor
42 {
43 private final Executor executor;
44
45 public ExecutorInterceptor( Executor executor )
46 {
47 this.executor = executor;
48 }
49
50 public Object intercept( final Invocation invocation ) throws Throwable
51 {
52 if( Void.TYPE.equals( invocation.getMethod().getReturnType() ) )
53 {
54 // Special case for finalize() method (should not be run in a different thread)...
55 if( !( invocation.getMethod().getName().equals( "finalize" ) &&
56 invocation.getMethod().getParameterTypes().length == 0 ) )
57 {
58 executor.execute( new Runnable()
59 {
60 public void run()
61 {
62 try
63 {
64 invocation.proceed();
65 }
66 catch( Throwable t )
67 {
68 // What to do here? I can't convey the failure back to the caller.
69 }
70 }
71 } );
72 return null;
73 }
74 else
75 {
76 return invocation.proceed();
77 }
78 }
79 else
80 {
81 throw new IllegalArgumentException( "Only void methods can be executed in a different thread." );
82 }
83 }
84 }