01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one
03: * or more contributor license agreements. See the NOTICE file
04: * distributed with this work for additional information
05: * regarding copyright ownership. The ASF licenses this file
06: * to you under the Apache License, Version 2.0 (the
07: * "License"); you may not use this file except in compliance
08: * with the License. You may obtain a copy of the License at
09: *
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.IoBuffer;
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 MINA Project (dev@mina.apache.org)
33: * @version $Rev: 590006 $, $Date: 2007-10-30 03:44:02 -0600 (Tue, 30 Oct 2007) $
34: */
35: public abstract class AbstractMessageEncoder<T extends AbstractMessage>
36: implements MessageEncoder<T> {
37: private final int type;
38:
39: protected AbstractMessageEncoder(int type) {
40: this .type = type;
41: }
42:
43: public void encode(IoSession session, T message,
44: ProtocolEncoderOutput out) throws Exception {
45: IoBuffer buf = IoBuffer.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(message.getSequence());
51:
52: // Encode a body
53: encodeBody(session, message, buf);
54: buf.flip();
55: out.write(buf);
56: }
57:
58: protected abstract void encodeBody(IoSession session, T message,
59: IoBuffer out);
60: }
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