分隔符与定长解码器的使用

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netty 的分隔符与定长解码器的使用

4种解码器应对TCP的粘包、拆包问题

new ChannelInitializer() {
public void initChannel(SocketChannel ch) {
ChannelPipeline pl = ch.pipeline();
//pl.addLast(new LineBasedFrameDecoder(64)); //换行符解码
//pl.addLast(new FixedLengthFrameDecoder(3)); //固定长度解码

//消息以#作为分隔符，当达到单个消息的最大长度仍然没有查到分隔符，抛出TooLongFrameException
// ByteBuf delimiter = Unpooled.copiedBuffer("#".getBytes());
// pl.addLast(new DelimiterBasedFrameDecoder(16, delimiter));
pl.addLast(new SimpleDecoder());
pl.addLast(new SeverHandler());
}

LengthFieldBasedFrameDecoder 有点问题
public class SimpleDecoder extends LengthFieldBasedFrameDecoder {

    private static final int FRAME_MAX_LENGTH = 64;

    public SimpleDecoder() {
        super(FRAME_MAX_LENGTH, 0, 4, 0, 4);
    }

    @Override
    public Object decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
        ByteBuf frame = null;
        try {
            frame = (ByteBuf) super.decode(ctx, in);
            if (null == frame) {
                return null;
            }

            ByteBuffer byteBuffer = frame.nioBuffer();
            //return RemotingCommand.decode(byteBuffer);
            return decode(byteBuffer);
        } catch (Exception e) {
        e.printStackTrace();
        } finally {
            if (null != frame) {
                frame.release();
            }
        }

        return null;
    }
   /*
    public static RemotingCommand decode(final ByteBuffer byteBuffer) {
        int length = byteBuffer.limit();
        int oriHeaderLen = byteBuffer.getInt();
        int headerLength = getHeaderLength(oriHeaderLen);

        byte[] headerData = new byte[headerLength];
        byteBuffer.get(headerData);

        RemotingCommand cmd = headerDecode(headerData, getProtocolType(oriHeaderLen));

        int bodyLength = length - 4 - headerLength;
        byte[] bodyData = null;
        if (bodyLength > 0) {
            bodyData = new byte[bodyLength];
            byteBuffer.get(bodyData);
        }
        cmd.body = bodyData;

        return cmd;
    }
   
    public static String decode(final ByteBuffer byteBuffer) {
        int length = byteBuffer.limit();
        System.out.println("len="+length);

        byte[] headerData = new byte[length];
        byteBuffer.get(headerData);
        String res=null;
try {
res = new String(headerData, "utf-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
        return res;
    }
    */
   
    public static Object decode(final ByteBuffer byteBuffer) {
        int length = byteBuffer.limit();
        int oriHeaderLen = byteBuffer.getInt();
        System.out.println("decode..");
        int headerLength = oriHeaderLen;

        byte[] headerData = new byte[headerLength];
        byteBuffer.get(headerData);
       
        try {
String res = new String(headerData, "utf-8");
return res;
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

        //RemotingCommand cmd = headerDecode(headerData, getProtocolType(oriHeaderLen));
        /*
        int bodyLength = length - 4 - headerLength;
        byte[] bodyData = null;
        if (bodyLength > 0) {
            bodyData = new byte[bodyLength];
            byteBuffer.get(bodyData);
        }
        cmd.body = bodyData;
*/
        return null;
    }
}