/*
* 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: 448075 $, $Date: 2006-09-20 14:26:53 +0900 (수, 20 9월 2006) $
*/
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 );
}