packetdecoderchain.java

银行项目为后台ｓｏｃｋｅｔ通信写的程序

/****************************************************************************
 * Package		: com.ecSolutions.ecAppServer.server.decoder
 * File			: PacketDecoderChain.java
 * Create Date  : 2007-7-20
 * Author		: Steven Chen
 * 
 * Copyright(C) 2006 ecSolutions(shanghai) Co.,Limited.All Rights Reserved.
 *			
 ***************************************************************************/

package com.ecSolutions.ecAppServer.server.decoder;

import java.util.Collection;
import java.util.Iterator;

import com.ecSolutions.ecAppServer.server.Buffer;
import com.ecSolutions.ecAppServer.server.Packet;
import com.ecSolutions.ecAppServer.server.PacketDecoder;
import com.ecSolutions.ecAppServer.server.Session;
import edu.emory.mathcs.backport.java.util.concurrent.CopyOnWriteArrayList;

/**
 * <code>PacketDecoder</code> chain.
 * 
 * @author Steven Chen
 * @version $Id: PacketDecoderChain.java,v 1.3 2007/07/26 03:15:54 stevenchen Exp $
 */
public class PacketDecoderChain implements PacketDecoder {

    private final Collection chain = new CopyOnWriteArrayList();

    public PacketDecoderChain addPacketDecoder(PacketDecoder decoder) {
        if (decoder != null)
            chain.add(decoder);
        return this;
    }

    public PacketDecoderChain removePacketDecoder(PacketDecoder decoder) {
        chain.remove(decoder);
        return this;
    }

    public Object decode(Session session, Packet packet) throws Exception {
        Buffer content = packet.getContent();
        int position = content.position();
        int limit = content.limit();

        for (Iterator iter = chain.iterator(); iter.hasNext();) {
            PacketDecoder decoder = (PacketDecoder) iter.next();
            Object obj = decoder.decode(session, packet);
            if (obj != null)
                return obj;

            // not use slice to create new buffer, reduce memory cost
            content.limit(limit);
            content.position(position);
        }
        return null;
    }

}