View Javadoc

1   /*
2    *   @(#) $Id: AbstractMessageEncoder.java 355016 2005-12-08 07:00:30Z trustin $
3    *
4    *   Copyright 2004 The Apache Software Foundation
5    *
6    *   Licensed under the Apache License, Version 2.0 (the "License");
7    *   you may not use this file except in compliance with the License.
8    *   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, software
13   *   distributed under the License is distributed on an "AS IS" BASIS,
14   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   *   See the License for the specific language governing permissions and
16   *   limitations under the License.
17   *
18   */
19  package org.apache.mina.examples.sumup.codec;
20  
21  import org.apache.mina.common.ByteBuffer;
22  import org.apache.mina.common.IoSession;
23  import org.apache.mina.examples.sumup.message.AbstractMessage;
24  import org.apache.mina.filter.codec.ProtocolEncoderOutput;
25  import org.apache.mina.filter.codec.demux.MessageEncoder;
26  
27  /***
28   * A {@link MessageEncoder} that encodes message header and forwards
29   * the encoding of body to a subclass.
30   *
31   * @author The Apache Directory Project
32   * @version $Rev: 355016 $, $Date: 2005-12-08 16:00:30 +0900 (Thu, 08 Dec 2005) $
33   */
34  public abstract class AbstractMessageEncoder implements MessageEncoder
35  {
36      private final int type;
37  
38      protected AbstractMessageEncoder( int type )
39      {
40          this.type = type;
41      }
42  
43      public void encode( IoSession session, Object message, ProtocolEncoderOutput out ) throws Exception
44      {
45          AbstractMessage m = ( AbstractMessage ) message ;
46          ByteBuffer buf = ByteBuffer.allocate( 16 );
47          buf.setAutoExpand( true ); // Enable auto-expand for easier encoding
48          
49          // Encode a header
50          buf.putShort( ( short ) type );
51          buf.putInt( m.getSequence() );
52          
53          // Encode a body
54          encodeBody( session, m, buf );
55          buf.flip();
56          out.write( buf );
57      }
58      
59      protected abstract void encodeBody( IoSession session, AbstractMessage message, ByteBuffer out );
60  }