/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* 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
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
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.ProtocolDecoderOutput;
import org.apache.mina.filter.codec.demux.MessageDecoder;
import org.apache.mina.filter.codec.demux.MessageDecoderResult;
/**
* A {@link MessageDecoder} that decodes message header and forwards
* the decoding of body to a subclass.
*
* @author The Apache Directory Project (mina-dev@directory.apache.org)
* @version $Rev: 555855 $, $Date: 2007-07-13 05:19:00 +0200 (Fri, 13 Jul 2007) $
*/
public abstract class AbstractMessageDecoder implements MessageDecoder {
private final int type;
private int sequence;
private boolean readHeader;
protected AbstractMessageDecoder(int type) {
this.type = type;
}
public MessageDecoderResult decodable(IoSession session, ByteBuffer in) {
// Return NEED_DATA if the whole header is not read yet.
if (in.remaining() < Constants.HEADER_LEN) {
return MessageDecoderResult.NEED_DATA;
}
// Return OK if type and bodyLength matches.
if (type == in.getShort()) {
return MessageDecoderResult.OK;
}
// Return NOT_OK if not matches.
return MessageDecoderResult.NOT_OK;
}
public MessageDecoderResult decode(IoSession session, ByteBuffer in,
ProtocolDecoderOutput out) throws Exception {
// Try to skip header if not read.
if (!readHeader) {
in.getShort(); // Skip 'type'.
sequence = in.getInt(); // Get 'sequence'.
readHeader = true;
}
// Try to decode body
AbstractMessage m = decodeBody(session, in);
// Return NEED_DATA if the body is not fully read.
if (m == null) {
return MessageDecoderResult.NEED_DATA;
} else {
readHeader = false; // reset readHeader for the next decode
}
m.setSequence(sequence);
out.write(m);
return MessageDecoderResult.OK;
}
/**
* @return <tt>null</tt> if the whole body is not read yet
*/
protected abstract AbstractMessage decodeBody(IoSession session,
ByteBuffer in);
}