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Java > Open Source Codes > org > apache > mina > example > sumup > codec > AbstractMessageEncoder


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.example.sumup.codec;
21
22 import org.apache.mina.common.ByteBuffer;
23 import org.apache.mina.common.IoSession;
24 import org.apache.mina.example.sumup.message.AbstractMessage;
25 import org.apache.mina.filter.codec.ProtocolEncoderOutput;
26 import org.apache.mina.filter.codec.demux.MessageEncoder;
27
28 /**
29  * A {@link MessageEncoder} that encodes message header and forwards
30  * the encoding of body to a subclass.
31  *
32  * @author The Apache Directory Project (mina-dev@directory.apache.org)
33  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $
34  */
35 public abstract class AbstractMessageEncoder implements MessageEncoder {
36     private final int type;
37
38     protected AbstractMessageEncoder(int type) {
39         this.type = type;
40     }
41
42     public void encode(IoSession session, Object JavaDoc message,
43             ProtocolEncoderOutput out) throws Exception JavaDoc {
44         AbstractMessage m = (AbstractMessage) message;
45         ByteBuffer buf = ByteBuffer.allocate(16);
46         buf.setAutoExpand(true); // Enable auto-expand for easier encoding
47
48         // Encode a header
49 buf.putShort((short) type);
50         buf.putInt(m.getSequence());
51
52         // Encode a body
53 encodeBody(session, m, buf);
54         buf.flip();
55         out.write(buf);
56     }
57
58     protected abstract void encodeBody(IoSession session,
59             AbstractMessage message, ByteBuffer out);
60 }
61
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