/*
* @(#) $Id: AbstractMessageDecoder.java 210062 2005-07-11 03:52:38Z trustin $
*
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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.examples.sumup.codec;
import org.apache.mina.common.ByteBuffer;
import org.apache.mina.examples.sumup.message.AbstractMessage;
import org.apache.mina.protocol.ProtocolDecoderOutput;
import org.apache.mina.protocol.ProtocolSession;
import org.apache.mina.protocol.ProtocolViolationException;
import org.apache.mina.protocol.codec.MessageDecoder;
import org.apache.mina.protocol.codec.MessageDecoderResult;
/**
* A {@link MessageDecoder} that decodes message header and forwards
* the decoding of body to a subclass.
*
* @author The Apache Directory Project
* @version $Rev: 210062 $, $Date: 2005-07-11 12:52:38 +0900 $
*/
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( ProtocolSession 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( ProtocolSession session, ByteBuffer in, ProtocolDecoderOutput out ) throws ProtocolViolationException
{
// 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( ProtocolSession session, ByteBuffer in );
}