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

• @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 = 《一线大厂 Java 面试题解析+后端开发学习笔记+最新架构讲解视频+实战项目源码讲义》无偿开源 威信搜索公众号【编程进阶路】 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)