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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.handler.chain;
21  
22  import org.apache.mina.core.service.IoHandler;
23  import org.apache.mina.core.service.IoHandlerAdapter;
24  import org.apache.mina.core.session.IoSession;
25  
26  /**
27   * An {@link IoHandler} which executes an {@link IoHandlerChain}
28   * on a <tt>messageReceived</tt> event.
29   *
30   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31   */
32  public class ChainedIoHandler extends IoHandlerAdapter {
33      private final IoHandlerChain chain;
34  
35      /**
36       * Creates a new instance which contains an empty {@link IoHandlerChain}.
37       */
38      public ChainedIoHandler() {
39          chain = new IoHandlerChain();
40      }
41  
42      /**
43       * Creates a new instance which executes the specified
44       * {@link IoHandlerChain} on a <tt>messageReceived</tt> event.
45       *
46       * @param chain an {@link IoHandlerChain} to execute
47       */
48      public ChainedIoHandler(IoHandlerChain chain) {
49          if (chain == null) {
50              throw new IllegalArgumentException("chain");
51          }
52          this.chain = chain;
53      }
54  
55      /**
56       * Returns the {@link IoHandlerCommand} this handler will use to
57       * handle <tt>messageReceived</tt> events.
58       */
59      public IoHandlerChain getChain() {
60          return chain;
61      }
62  
63      /**
64       * Handles the specified <tt>messageReceived</tt> event with the
65       * {@link IoHandlerCommand} or {@link IoHandlerChain} you specified
66       * in the constructor.
67       */
68      @Override
69      public void messageReceived(IoSession session, Object message) throws Exception {
70          chain.execute(null, session, message);
71      }
72  }