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.core.buffer.IoBuffer;
23 import org.apache.mina.core.session.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 MINA Project (dev@mina.apache.org)
33 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (jeu, 26 jun 2008) $
34 */
35 public abstract class AbstractMessageEncoder<T extends AbstractMessage> implements MessageEncoder<T> {
36 private final int type;
37
38 protected AbstractMessageEncoder(int type) {
39 this.type = type;
40 }
41
42 public void encode(IoSession session, T message, ProtocolEncoderOutput out) throws Exception {
43 IoBuffer buf = IoBuffer.allocate(16);
44 buf.setAutoExpand(true); // Enable auto-expand for easier encoding
45
46 // Encode a header
47 buf.putShort((short) type);
48 buf.putInt(message.getSequence());
49
50 // Encode a body
51 encodeBody(session, message, buf);
52 buf.flip();
53 out.write(buf);
54 }
55
56 protected abstract void encodeBody(IoSession session, T message, IoBuffer out);
57 }