使用自定义协议实现Python向Netty传输数据

// 基于固定长度FixedLengthFrameDecoder// 使用固定长度字段存储内容的长度LengthFieldBasedFrameDecoder// 基于换行符LineBasedFrameDecoder// 基于分隔符DelimiterBasedFrameDecoder

#! /usr/bin/env python# -*- coding:utf-8 -*-
from socket import *import structimport json
class Book(object):
    def __init__(self, addr, year):        self.addr = addr        self.year = year
    def addr(self):        return self.addr
    def keys(self):        return ['addr', 'year']
    def __getitem__(self, item):        return getattr(self, item)

if __name__ == '__main__':    client = socket(AF_INET, SOCK_STREAM)    # 连接服务端    client.connect(('127.0.0.1', 8082))
    book = Book('成都', 2021)        # 将对象book转成JSON格式的数据    json = json.dumps(dict(book))    # 将JSON格式数据转成字节类型,用于网络传输    body = bytes(json, 'utf-8')    # 计算实际有效数据(body)的长度    body_len = len(body)
    # head中存body的长度    # I表示整型,即用一个整型大小空间存储body的长度; 而>表示按照大端存储, 至于什么是大端小端存储可以Google    head = struct.pack('>I', body_len)    # 按照我们自定义的协议格式,将字节数据发送到服务端    client.sendall(head + body)    

import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;import io.netty.handler.codec.LengthFieldBasedFrameDecoder;import io.netty.handler.logging.LogLevel;import io.netty.handler.logging.LoggingHandler;
public class Server {

    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);        EventLoopGroup workerGroup = new NioEventLoopGroup(8);
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        try {
            serverBootstrap.group(bossGroup, workerGroup)                    .channel(NioServerSocketChannel.class)                    .handler(new LoggingHandler(LogLevel.INFO))                    .childHandler(new ChannelInitializer<NioSocketChannel>() {                        @Override                        protected void initChannel(NioSocketChannel ch) {                            ChannelPipeline channelPipeline = ch.pipeline();                            // 按照我们自定义的协议,将有效数据解码出来,解码成有效的字节数据                            channelPipeline.addLast(new LengthFieldBasedFrameDecoder(1024, 0, 4, 0, 4));                            // 将解码出来的字节数据转换成实体对象                            channelPipeline.addLast(new MyDecoder());                            // 处理实体对象                            channelPipeline.addLast(new ServerHandler());
                        }                    });
            ChannelFuture channelFuture = serverBootstrap.bind("127.0.0.1", 8082).sync();            channelFuture.channel().closeFuture().sync();        } finally {            bossGroup.shutdownGracefully();            workerGroup.shutdownGracefully();        }    }}

import com.alibaba.fastjson.JSON;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.SimpleChannelInboundHandler;

public class MyDecoder extends SimpleChannelInboundHandler<ByteBuf> {

    @Override    protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
      // 进入到这个channelRead0方法就表明之前的LengthFieldBasedFrameDecoder解码器已经把有效body数据解码出来了, 这个channelRead0方法得到的就是body有效数据.        byte[] bytes = new byte[msg.readableBytes()];        msg.readBytes(bytes);
        String json = new String(bytes, "UTF-8");        MyModel v = JSON.parseObject(json, MyModel.class);        ctx.fireChannelRead(v);    }}

import io.netty.channel.ChannelHandlerContext;import io.netty.channel.SimpleChannelInboundHandler;

public class ServerHandler extends SimpleChannelInboundHandler<MyModel> {
    @Override    protected void channelRead0(ChannelHandlerContext ctx, MyModel msg) throws Exception {        System.out.println(msg.getAddr());    }}