abstractmessageencoder.java

MINA自带的一些小例子

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 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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 *  
 *    http://www.apache.org/licenses/LICENSE-2.0
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 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
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package org.apache.mina.example.sumup.codec;

import org.apache.mina.common.ByteBuffer;
import org.apache.mina.common.IoSession;
import org.apache.mina.example.sumup.message.AbstractMessage;
import org.apache.mina.filter.codec.ProtocolEncoderOutput;
import org.apache.mina.filter.codec.demux.MessageEncoder;

/**
 * A {@link MessageEncoder} that encodes message header and forwards
 * the encoding of body to a subclass.
 *
 * @author The Apache Directory Project ([e-mail])
 * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13  7월 2007) $
 */
public abstract class AbstractMessageEncoder implements MessageEncoder {
    private final int type;

    protected AbstractMessageEncoder(int type) {
        this.type = type;
    }

    public void encode(IoSession session, Object message,
            ProtocolEncoderOutput out) throws Exception {
        AbstractMessage m = (AbstractMessage) message;
        ByteBuffer buf = ByteBuffer.allocate(16);
        buf.setAutoExpand(true); // Enable auto-expand for easier encoding

        // Encode a header
        buf.putShort((short) type);
        buf.putInt(m.getSequence());

        // Encode a body
        encodeBody(session, m, buf);
        buf.flip();
        out.write(buf);
    }

    protected abstract void encodeBody(IoSession session,
            AbstractMessage message, ByteBuffer out);
}