Netty学习之旅------高仿Dubbo服务调用模型、私有协议实现、编码解码器使用实践

1、本文实现如下功能：
    1、客户端与服务端基于单一长连接进行通信，客户端一条连接被多个线程使用。
    2、实现私有协议
       请求协议    
          协议头：4字节的请求序列号 2字节的请求类型  2字节数据包长度
          数据部分：
                服务调用：2字节请求服务名长度 若干字节请求服务名 2字节请求参数长度  若干字节参数
               心跳包：数据部分无
       响应信息
          协议头：4字节的请求序列号 2字节的执行状态码 2字节数据长度
          数据部分： 多字节的响应数据信息(data)
    3、代码基于Netty5
几个核心类代码如下：

package persistent.prestige.demo.netty.dubbo.net;

import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import persistent.prestige.demo.netty.dubbo.utils.LogUtils;

/**
* 请求消息   解码器，实现自定义协议,,,用于服务端
*
* 自定义协议如下 4字节的请求序列号 2字节的请求类型 2字节数据长度 2字节服务调用长度 N字节的服务调用名 2字节请求参数长度 请求参数
* 其中请求类型为1：服务调用2：心跳包，如果是心跳包的话，只有协议头，也就是【4字节请求序列号，2字节请求类型，2字节数据长度】
*
* @author prestigeding@126.com
*
*/
public class RequestFrameDecoder extends ByteToMessageDecoder {

/** 协议头 长度 */
private static final int HEAD_LENGTH = 8;

/*
* (non-Javadoc)
*
* @param ctx Handler执行环境
*
* @param in //当前累积缓存区字节
*
* @param out //解码后的消息
*/
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in,
List<Object> out) throws Exception {
// TODO Auto-generated method stub

LogUtils.log("RequestFrameDecoder start calling....");

int r = in.readableBytes();
LogUtils.log("RequestFrameDecoder 累计缓存去大小：%d", r);

if (r < HEAD_LENGTH) {
LogUtils.log("RequestFrameDecoder 当前累积缓存区可读数据长度为%d,小于协议头的长度%d", r, HEAD_LENGTH);
return;
}

int currentReaderIndex = in.readerIndex();
int requestId = in.getInt(currentReaderIndex);// 0-3
short requestType = in.getShort(currentReaderIndex + 4);// 4-5
short contentLength = in.getShort(currentReaderIndex + 6);// 6-7 头部信息共8个字节

LogUtils.log("RequestFrameDecoder requestId:%d,requestType:%d,contentLength:%d", requestId, requestType, contentLength);

Request request = null;
if (requestType == 1) {
if (r < (HEAD_LENGTH + contentLength)) { // 如果累积缓存区可读容量小于一个请求包的长度，直接返回
LogUtils.log("RequestFrameDecoder 当前累积缓存区可读数据长度为%d,小于数据报的长度%d", r, HEAD_LENGTH + contentLength);
return;
}

// 否则，直接读取数据
in.skipBytes(HEAD_LENGTH);// 先跳过协议头信息

int slen = in.readShort();
byte[] serviceData = new byte[slen];
in.readBytes(serviceData, 0, slen);

short plen = in.readShort();
byte[] paramsData = new byte[plen];
in.readBytes(paramsData, 0, plen);

out.add(request = new Request(requestId, requestType,
new String(serviceData), new String(paramsData)));
request.setContentLength(contentLength); //这里，其实上层应用不需要知道请求包的长度，这里属于多于的操作

LogUtils.log("RequestFrameDecoder 成功从服务端响应中解析出业务包,requestId:%d", requestId);

} else if (requestType == 2) { // 此处不对请求类型进行校验
in.skipBytes(HEAD_LENGTH);
out.add(request = new Request(requestId, requestType));
request.setContentLength(contentLength); //这里，其实上层应用不需要知道请求包的长度，这里属于多于的操作
LogUtils.log("RequestFrameDecoder 成功从服务端响应中解析出心跳包,requestId:%d", requestId);
}

}

}

package persistent.prestige.demo.netty.dubbo.net;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import persistent.prestige.demo.netty.dubbo.utils.LogUtils;
/**
* 请求消息编码器，实现自定义协议,用于客户端
*
* 自定义协议如下
* 4字节的请求序列号  2字节的请求类型  2字节数据长度 2字节服务调用长度 N字节的服务调用名 2字节请求参数长度  请求参数
* 其中请求类型为1：服务调用2：心跳包，如果是心跳包的话，只有协议头，也就是【4字节请求序列号，2字节请求类型，2字节数据长度】
*
* @author prestigeding@126.com
*
*/
public class RequestFrameEncoder extends MessageToByteEncoder<Request> {

@Override
protected void encode(ChannelHandlerContext ctx, Request msg, ByteBuf out)
throws Exception {

LogUtils.log("RequestFrameEncoder begin calling...requestId:%d,requestType:%d.",msg.getRequestId(), msg.getRequestType());

out.writeInt(msg.getRequestId());  // requestId
out.writeShort(msg.getRequestType());          // requestType

if(msg.getRequestType() == 1 ) { //服务调用
byte[] serviceData = msg.getService().getBytes();
byte[] paramsData = msg.getParams().getBytes();
int slen, plen;
out.writeShort((
2 + (slen = serviceData.length) +
2 + (plen = paramsData.length)));

out.writeShort(slen);
out.writeBytes(serviceData);
out.writeShort(plen);
out.writeBytes(paramsData);

} else if(msg.getRequestType() == 2 ) { //心跳包
out.writeShort(0);
}

LogUtils.log("RequestFrameEncoder end call....");

}

}

package persistent.prestige.demo.netty.dubbo.net;

import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import persistent.prestige.demo.netty.dubbo.utils.LogUtils;

/**
* 响应信息解码器  用于客户端
* @author dingwei2
*
* 响应报文格式
* 4字节的请求序列号 2字节的执行状态码 2字节数据长度 多字节的响应数据信息(data)
*
*/
public class ResponseFrameDecoder extends ByteToMessageDecoder {
private static final int HEAD_LENGTH = 8;

@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {

LogUtils.log("ResponseFrameDecoder start calling....");

// TODO Auto-generated method stub
int r = in.readableBytes();

LogUtils.log("ResponseFrameDecoder 累积缓存区中可读长度:%d", r);

if(r < HEAD_LENGTH ) {
LogUtils.log("ResponseFrameDecoder 当前累积缓存区可读数据长度为%d,小于协议头的长度%d", r, HEAD_LENGTH);
return;
}

int currentReaderIndex = in.readerIndex();
int requestId = in.getInt(currentReaderIndex); // 0-3 4个字节
short code = in.getShort(currentReaderIndex + 4);  // 4,5
short contentLength = in.getShort(currentReaderIndex + 6); //响应数据长度

LogUtils.log("ResponseFrameDecoder requestId:%d,code:%d,contentLength:%d", requestId, code, contentLength);

int packetLen;

if( r < (packetLen = HEAD_LENGTH + contentLength))  {
LogUtils.log("ResponseFrameDecoder 可读长度:%d,需要包长度:%d", r, packetLen);
return;
}

in.skipBytes( HEAD_LENGTH );

String data;
if(contentLength > 0 ) {
byte[] dst = new byte[contentLength];
in.readBytes(dst, 0, contentLength);
data = new String(dst);
} else {
data = "";
}

out.add(new Response(requestId, code, new String(data)));
LogUtils.log("ResponseFrameDecoder 成功解析服务端响应信息并准备给下游处理器处理");

}

}

package persistent.prestige.demo.netty.dubbo.net;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import persistent.prestige.demo.netty.dubbo.utils.LogUtils;

/**
* 响应信息 编码器，，用于服务器
* @author dingwei2
*
* 响应报文格式
* 4字节的请求序列号 2字节的执行状态码 2字节数据长度 多字节的响应数据信息(data)
*
*/
public class ResponseFrameEncoder extends MessageToByteEncoder<Response> {

@Override
protected void encode(ChannelHandlerContext ctx, Response msg, ByteBuf out) throws Exception {
// TODO Auto-generated method stub
LogUtils.log("ResponseFrameEncoder:服务端编码响应,requestId:%d,code:%d,data:%s", msg.getRequestId(), msg.getCode(), msg.getData());
out.writeInt(msg.getRequestId());
out.writeShort(msg.getCode());
byte[] data = msg.getData().getBytes();
out.writeShort(data.length);
out.writeBytes(data);
LogUtils.log("ResponseFrameEncoder:服务端编码响应成功");

}

}

package persistent.prestige.demo.netty.dubbo.net;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import persistent.prestige.demo.netty.dubbo.net.heart.HeartExecutorThreadPool;
import persistent.prestige.demo.netty.dubbo.net.heart.HeartTask;
import persistent.prestige.demo.netty.dubbo.utils.LogUtils;

/**
* netty 客户端 connection 一个NettyConnection 就是一条长连接
* @author prestigeding@126.com
*
*/
public class NettyClientConnection {

private String serverIp;
private int serverPort;

private boolean connect = false;

private Bootstrap bootstrap;
private NioEventLoopGroup workGroup;

private ChannelFuture channelFuture;

//客户端连接请求
private static final ConcurrentHashMap<Integer, ResponseFuture> requestMap = new ConcurrentHashMap<Integer, ResponseFuture>();
private static final AtomicInteger seq = new AtomicInteger(0);

private HeartExecutorThreadPool heartExecutor = null;

/**
*
* @param serverIp
* @param serverPort
*/
public NettyClientConnection(String serverIp, int serverPort) {
this.serverIp = serverIp;
this.serverPort = serverPort;

workGroup = new NioEventLoopGroup();

bootstrap = new Bootstrap();

bootstrap.group(workGroup)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch)
throws Exception {
// TODO Auto-generated method stub
ch.pipeline().addLast(new ResponseFrameDecoder())
.addLast(new RequestFrameEncoder())
.addLast(new DispatchHandler());

}

});

}

private void connect() {
if(!connect) {

synchronized (this) {
try {
if(!connect) {
channelFuture = bootstrap.connect(serverIp, serverPort).sync();
heartExecutor = new HeartExecutorThreadPool(0, this, 3);
connect = true;

heartExecutor.scheduleAtFixedRate(new HeartTask(this), 1, 3, TimeUnit.SECONDS);//单位为秒
}

} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
throw new NullPointerException("连接服务端失败");
}
}

}
}

/**
* 发送服务调用
* @param service
* @param params
* @return
*/
public ResponseFuture sendMsg(String service, String params) {
Integer requestId = seq.incrementAndGet();
System.out.println("客户端requestId:" + requestId);
return send(new Request(requestId, (short)1, service, params));
}

/**
* 发送心跳包
* @return
*/
public ResponseFuture sendHeatMsg() {
Integer requestId = seq.incrementAndGet();
return send(new Request(requestId, (short)2));
}

private ResponseFuture send(Request request) {
connect();
ResponseFuture responseFuture = new ResponseFuture();
requestMap.putIfAbsent(request.getRequestId(), responseFuture);
channelFuture.channel().writeAndFlush(request);
return responseFuture;
}

/**
* 关闭连接
*/
public void close() {
try {
channelFuture.channel().close().sync();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
workGroup.shutdownGracefully();
if(heartExecutor != null) {
heartExecutor.shutdownNow();
}
}
}

/**
* 客户端命令转发器
* @author prestigeding@126.com
*
*/
private class DispatchHandler extends ChannelHandlerAdapter {

/**
* 得到服务端的响应后，放入结果中，供客户端使用结果
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
LogUtils.log("客户端收到服务端响应，并开始处理数据");
Response response = (Response)msg;
LogUtils.log("服务端响应requestId:", response.getRequestId());
ResponseFuture f = requestMap.remove(response.getRequestId());
if(f != null) {
f.setResult(response);
} else {
LogUtils.log("警告：客户端丢失请求信息");
}

}

}

}

完整代码如下：http://download.csdn.net/detail/prestigeding/9775190

其中Server是服务器启动类，Client 是客户端启动类。