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 (Fri, 13 Jul 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 message,
43 ProtocolEncoderOutput out) throws Exception {
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 }