Mina框架实现最简单的服务端（二）

编解码工厂。因为网络通讯过程中用的协议不一样，不同协议的消息格式不同，所以需要有编解码器实现字节流到具体消息对象的转换。通常在解码过程中如果出现解码错误，说明消息在传递过程中可能存在丢失或更改的情况，这时需要将与客户端的会话关闭。

package minabase.server;

import org.apache.mina.filter.codec.demux.DemuxingProtocolCodecFactory;
import org.apache.mina.filter.codec.demux.MessageDecoder;
import org.apache.mina.filter.codec.demux.MessageEncoder;

/**
* Class Description: 编解码工厂
* Copyright:   Copyright (c)
*
*/
public class MyCodecFactory extends DemuxingProtocolCodecFactory
{
private MessageDecoder decoder;

private MessageEncoder<String> encoder;

// 注册编解码器
public MyCodecFactory(MessageDecoder decoder, MessageEncoder<String> encoder)
{
this.decoder = decoder;
this.encoder = encoder;

addMessageDecoder(this.decoder);
addMessageEncoder(String.class, this.encoder);
}
}

编码器

package minabase.server;

import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;

import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolEncoderOutput;
import org.apache.mina.filter.codec.demux.MessageEncoder;

/**
* Class Description: 编码器，在每个消息后面加\n
* Copyright:   Copyright (c)
*
*/
public class MyCodecEncoder implements MessageEncoder<String>
{
private CharsetEncoder cecoder;

public MyCodecEncoder(Charset charset)
{
cecoder = charset.newEncoder();
}

@Override
public void encode(IoSession session, String in, ProtocolEncoderOutput out)
throws Exception
{
IoBuffer buf = IoBuffer.allocate(100).setAutoExpand(true);
String strMsg = in.toString();
try
{
buf.putString(strMsg, cecoder);
buf.put((byte)'\n');
}
catch (CharacterCodingException e)
{
//log
}

buf.flip();

out.write(buf);
}

}