Netty进阶——粘包与半包（代码示例)

Posted 小志的博客

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Netty进阶——粘包与半包（代码示例)相关的知识，希望对你有一定的参考价值。

目录

一、消息粘包和消息半包的概述

1.1、消息粘包

  • 当缓冲区足够大，由于网络不稳定种种原因，可能会有多条消息从通道读入缓冲区，此时如果无法分清数据包之间的界限，就会导致粘包问题。

1.2、消息半包

  • 若消息没有接收完，缓冲区就被填满了，会导致从缓冲区取出的消息不完整，即半包的现象。

二、粘包现象代码示例

2.1、粘包现象服务端示例代码

  • 服务端代码

    package com.example.nettytest.netty.day5;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioserverSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

/**
 * @description:   Netty粘包现象演示服务端
 *                 消息粘包：当缓冲区足够大，由于网络不稳定种种原因，可能会有多条消息从通道读入缓冲区，
 *                         此时如果无法分清数据包之间的界限，就会导致粘包问题；
 * @author: xz
 */
@Slf4j
public class NettyServerTest 

    public static void main(String[] args) 
        new NettyServerTest().start();
    

    void start() 
        NioEventLoopGroup boss = new NioEventLoopGroup(1);
        NioEventLoopGroup worker = new NioEventLoopGroup();
        try 
            ServerBootstrap serverBootstrap = new ServerBootstrap()
                .channel(NioServerSocketChannel.class)
                .group(boss, worker)
                .childHandler(new ChannelInitializer<SocketChannel>() 
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception 
                        ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                        ch.pipeline().addLast(new ChannelInboundHandlerAdapter() 
                            //会在连接channel建立成功后，触发active事件
                            @Override
                            public void channelActive(ChannelHandlerContext ctx) throws Exception 
                                log.debug("connected>>>>>>>>>>>>>>>> ", ctx.channel());
                                super.channelActive(ctx);
                            
                            @Override
                            public void channelInactive(ChannelHandlerContext ctx) throws Exception 
                                log.debug("disconnect>>>>>>>>>>>>>>>> ", ctx.channel());
                                super.channelInactive(ctx);
                            
                        );
                    
                );
            ChannelFuture channelFuture = serverBootstrap.bind(8080);
            log.debug(">>>>>>>>>>>>>>>> binding...", channelFuture.channel());
            channelFuture.sync();
            log.debug(">>>>>>>>>>>>>>>> bound...", channelFuture.channel());
            channelFuture.channel().closeFuture().sync();
         catch (InterruptedException e) 
            log.error("server error", e);
         finally 
            boss.shutdownGracefully();
            worker.shutdownGracefully();
            log.debug(">>>>>>>>>>>>>>>>stoped");

2.2、粘包现象客户端示例代码

  • 客户端代码示例

    package com.example.nettytest.netty.day5;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
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 lombok.extern.slf4j.Slf4j;
/**
 * @description: Netty粘包现象演示客户端
 * @author: xz
 */
@Slf4j
public class NettyClientTest 

    public static void main(String[] args) 
        new NettyClientTest().start();
    

    void start() 
        NioEventLoopGroup worker = new NioEventLoopGroup();
        try 
            Bootstrap bootstrap = new Bootstrap()
                .channel(NioSocketChannel.class)
                .group(worker)
                .handler(new ChannelInitializer<SocketChannel>() 
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception 
                        log.debug("connetted》》》》》》》》》》》》》》》");
                        ch.pipeline().addLast(new ChannelInboundHandlerAdapter() 
                            //会在连接channel建立成功后，触发active事件
                            @Override
                            public void channelActive(ChannelHandlerContext ctx) throws Exception 
                                log.debug("遍历 sending 每次发送16个字节》》》》》》》》》》》》》》》");
                                for (int i = 0; i < 10; i++) 
                                    //设置缓冲区大小16个字节
                                    ByteBuf buffer = ctx.alloc().buffer(16);
                                    buffer.writeBytes(new byte[]1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16);
                                    ctx.writeAndFlush(buffer);
                                
                            
                        );
                    
                );
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8080).sync();
            channelFuture.channel().closeFuture().sync();
         catch (InterruptedException e) 
            log.error("client error", e);
         finally 
            worker.shutdownGracefully();

2.3、分别启动服务端，客户端，查看服务端结果输出

  • 先启动服务端
  • 再启动客户端
  • 再次查看服务端
    注：可下图输出结果可知：服务器端的某次输出，可以看到一次就接收了 160 个字节，而非分 10 次接收。

三、半包现象代码示例

3.1、半包现象服务端示例代码

  • 为现象明显，服务端添加一下接收缓冲区，其它代码不变

    serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);

  • 服务端完整示例代码

    package com.example.nettytest.netty.day5;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;
/**
 * @description:   Netty半包现象演示服务端
 *                 消息半包：若消息没有接收完，缓冲区就被填满了，会导致从缓冲区取出的消息不完整，即半包的现象。
 * @author: xz
 */
@Slf4j
public class NettyServerTest1 
    public static void main(String[] args) 
        new NettyServerTest().start();
    

    void start() 
        NioEventLoopGroup boss = new NioEventLoopGroup(1);
        NioEventLoopGroup worker = new NioEventLoopGroup();
        try 
            ServerBootstrap serverBootstrap = new ServerBootstrap()
                    .channel(NioServerSocketChannel.class)
                    //服务端添加接收缓冲区，大小设置10
                    .option(ChannelOption.SO_RCVBUF, 10)
                    .group(boss, worker)
                    .childHandler(new ChannelInitializer<SocketChannel>() 
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception 
                            ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                            ch.pipeline().addLast(new ChannelInboundHandlerAdapter() 
                                @Override
                                public void channelActive(ChannelHandlerContext ctx) throws Exception 
                                    log.debug("connected================== ", ctx.channel());
                                    super.channelActive(ctx);
                                
                                @Override
                                public void channelInactive(ChannelHandlerContext ctx) throws Exception 
                                    log.debug("disconnect================== ", ctx.channel());
                                    super.channelInactive(ctx);
                                
                            );
                        
                    );
            ChannelFuture channelFuture = serverBootstrap.bind(8080);
            log.debug(" binding====================", channelFuture.channel());
            channelFuture.sync();
            log.debug(" bound====================", channelFuture.channel());
            channelFuture.channel().closeFuture().sync();
         catch (InterruptedException e) 
            log.error("server error", e);
         finally 
            boss.shutdownGracefully();
            worker.shutdownGracefully();
            log.debug("stoped======================");

3.2、半包现象客户端示例代码