备案控制台
探索云世界
开发者社区 开发与运维 文章 正文

【Netty】TCP粘包和拆包

2022-05-05 121
版权
版权声明：
本文内容由阿里云实名注册用户自发贡献，版权归原作者所有，阿里云开发者社区不拥有其著作权，亦不承担相应法律责任。具体规则请查看《 阿里云开发者社区用户服务协议》和 《阿里云开发者社区知识产权保护指引》。如果您发现本社区中有涉嫌抄袭的内容，填写 侵权投诉表单进行举报，一经查实，本社区将立刻删除涉嫌侵权内容。
简介： 前面已经基本上讲解完了Netty的主要内容，现在来学习Netty中的一些可能存在的问题，如TCP粘包和拆包。

一、前言

　　前面已经基本上讲解完了Netty的主要内容，现在来学习Netty中的一些可能存在的问题，如TCP粘包和拆包。


二、粘包和拆包

　　对于TCP协议而言，当底层发送消息和接受消息时，都需要考虑TCP的粘包和拆包问题，一个完整的数据包可能会被TCP拆分为多个包发送，或者将多个小的数据包封装成大的数据包发送。

　　2.1 粘包和拆包基础

　　假设客户端发送D1和D2两个数据包至服务端，由于服务端每次读取的数据大小时不确定的，因此，可能存在如下四种情况。

　　1.png

　　① 服务端分两次读取到数据包，分别为D1和D2，没有粘包和拆包。

　　② 服务端一次读取两个数据包D1和D2，D1和D2黏合在一起，称为TCP粘包。

　　③ 服务端一次读取完整的D1数据包和D2数据包的一部分，第二次读取D2剩余的部分，称为TCP拆包。

　　④ 服务端一次读取D1数据包的一部分，第二次读取D1的剩余部分和D2数据包。

　　可以看到，在底层发送数据时，可能会发生粘包和拆包，其原因大致有如下三种。

　　① 应用程序写入字节大小大于套接字缓冲区大小。

　　② 进行MSS（Max Segment Size）大小的TCP分段。

　　③ 以太网帧的负载大于MTU（Maximum Transmission Unit）进行分片。

　　由于底层的TCP协议无法理解上层的业务数据，所以底层无法保证数据不被拆分和重组，而为了解决粘包问题，业界主要的策略如下。

　　① 消息定长，如每个报文大小固定为200个字节，如果不够，空格补位。

　　② 在包尾添加回车换行符进行分割，如FTP协议。

　　③ 将消息划分为消息头和消息体，消息头中包含消息总长度的字段。

　　2.2 TCP粘包示例

　　下面通过一个示例展示未考虑粘包问题导致的异常。

　　1. TimeServerHandler　

package com.hust.grid.leesf.chapter4;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeServerHandler extends ChannelInboundHandlerAdapter {
    private int counter;
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8").substring(0, req.length
                - System.getProperty("line.separator").length());
        System.out.println("The time server receive order : " + body
                + " ; the counter is : " + ++counter);
        String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(
                System.currentTimeMillis()).toString() : "BAD ORDER";
        currentTime = currentTime + System.getProperty("line.separator");
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.writeAndFlush(resp);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

　2. TimeServer

package com.hust.grid.leesf.chapter4;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeServer {
    public void bind(int port) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChildChannelHandler());
            ChannelFuture f = b.bind(port).sync();
            f.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
    private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {
        @Override
        protected void initChannel(SocketChannel arg0) throws Exception {
            arg0.pipeline().addLast(new TimeServerHandler());
        }
    }
    public static void main(String[] args) throws Exception {
        int port = 8080;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
                // ignore
            }
        }
        new TimeServer().bind(port);
    }
}

3. TimeClientHandler　

package com.hust.grid.leesf.chapter4;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.util.logging.Logger;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeClientHandler extends ChannelInboundHandlerAdapter {
    private static final Logger logger = Logger
            .getLogger(TimeClientHandler.class.getName());
    private int counter;
    private byte[] req;
    public TimeClientHandler() {
        req = ("QUERY TIME ORDER" + System.getProperty("line.separator"))
                .getBytes();
    }
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ByteBuf message = null;
        for (int i = 0; i < 100; i++) {
            message = Unpooled.buffer(req.length);
            message.writeBytes(req);
            ctx.writeAndFlush(message);
        }
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("Now is : " + body + " ; the counter is : "
                + ++counter);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

　4. TimeClient　

package com.hust.grid.leesf.chapter4;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeClient {
    public void connect(int port, String host) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch)
                                throws Exception {
                            ch.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            ChannelFuture f = b.connect(host, port).sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
    public static void main(String[] args) throws Exception {
        int port = 8080;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
                // ignore
            }
        }
        new TimeClient().connect(port, "127.0.0.1");
    }
}

分别运行服务器和客户端，其中服务器的运行结果如下：　

The time server receive order : QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORD ; the counter is : 1
The time server receive order : 
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER
QUERY TIME ORDER ; the counter is : 2

客户端的运行结果如下：

Now is : BAD ORDER
BAD ORDER
 ; the counter is : 1

可以看到服务端只接收到了两条消息，一条消息包含了57条指令，另一条包含了43条指令，其与我们设计的100条单独的消息不相符，发生了粘包。对于客户端而言，其收到了两条BAD ORDER，表示收到了两条消息，counter应该为2，但是其counter为1，表示也发生了粘包。

　　下面通过Netty的LineBasedFrameDecoder和String来解决粘包问题。

　　1. TimeServerHandler　

package com.hust.grid.leesf.chapter4.fault;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeServerHandler extends ChannelInboundHandlerAdapter {
    private int counter;
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8").substring(0, req.length
                - System.getProperty("line.separator").length());
        System.out.println("The time server receive order : " + body
                + " ; the counter is : " + ++counter);
        String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(
                System.currentTimeMillis()).toString() : "BAD ORDER";
        currentTime = currentTime + System.getProperty("line.separator");
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.writeAndFlush(resp);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

　2. TimeServer　

package com.hust.grid.leesf.chapter4.fault;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeServer {
    public void bind(int port) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChildChannelHandler());
            ChannelFuture f = b.bind(port).sync();
            f.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
    private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {
        @Override
        protected void initChannel(SocketChannel arg0) throws Exception {
            arg0.pipeline().addLast(new TimeServerHandler());
        }
    }
    public static void main(String[] args) throws Exception {
        int port = 8080;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
                // ignore
            }
        }
        new TimeServer().bind(port);
    }
}

3. TimeClientHandler

package com.hust.grid.leesf.chapter4.correct;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.util.logging.Logger;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeClientHandler extends ChannelInboundHandlerAdapter {
    private int counter;
    private byte[] req;
    public TimeClientHandler() {
        req = ("QUERY TIME ORDER" + System.getProperty("line.separator"))
                .getBytes();
    }
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ByteBuf message = null;
        for (int i = 0; i < 100; i++) {
            message = Unpooled.buffer(req.length);
            message.writeBytes(req);
            ctx.writeAndFlush(message);
        }
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        String body = (String) msg;
        System.out.println("Now is : " + body + " ; the counter is : "
                + ++counter);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

4. TimeClient

package com.hust.grid.leesf.chapter4.correct;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
/**
 * Created by Leesf on 2017/6/28.
 */
public class TimeClient {
    public void connect(int port, String host) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch)
                                throws Exception {
                            ch.pipeline().addLast(
                                    new LineBasedFrameDecoder(1024));
                            ch.pipeline().addLast(new StringDecoder());
                            ch.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            ChannelFuture f = b.connect(host, port).sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
    public static void main(String[] args) throws Exception {
        int port = 8080;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
                // ignore
            }
        }
        new TimeClient().connect(port, "127.0.0.1");
    }
}

分别运行服务端和客户端，服务端结果如下：

"D:\Program Files (x86)\Java\jdk1.8.0_65\bin\java" "-javaagent:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2017.1.4\lib\idea_rt.jar=62564:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2017.1.4\bin" -Dfile.encoding=UTF-8 -classpath "D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\charsets.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\deploy.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\access-bridge-64.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\cldrdata.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\dnsns.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jaccess.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jfxrt.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\localedata.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\nashorn.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunec.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunjce_provider.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunmscapi.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunpkcs11.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\zipfs.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\javaws.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jce.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfr.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfxswt.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jsse.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\management-agent.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\plugin.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\resources.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\rt.jar;F:\01_Code\02_Idea\CoreInNetty\target\classes;C:\Users\lsf\.m2\repository\io\netty\netty-all\4.0.32.Final\netty-all-4.0.32.Final.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-core\2.6.3\jackson-core-2.6.3.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-databind\2.6.3\jackson-databind-2.6.3.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-annotations\2.6.0\jackson-annotations-2.6.0.jar" com.hust.grid.leesf.chapter4.correct.TimeServer
The time server receive order : QUERY TIME ORDER ; the counter is : 1
The time server receive order : QUERY TIME ORDER ; the counter is : 2
The time server receive order : QUERY TIME ORDER ; the counter is : 3
The time server receive order : QUERY TIME ORDER ; the counter is : 4
The time server receive order : QUERY TIME ORDER ; the counter is : 5
The time server receive order : QUERY TIME ORDER ; the counter is : 6
The time server receive order : QUERY TIME ORDER ; the counter is : 7
The time server receive order : QUERY TIME ORDER ; the counter is : 8
The time server receive order : QUERY TIME ORDER ; the counter is : 9
The time server receive order : QUERY TIME ORDER ; the counter is : 10
The time server receive order : QUERY TIME ORDER ; the counter is : 11
The time server receive order : QUERY TIME ORDER ; the counter is : 12
The time server receive order : QUERY TIME ORDER ; the counter is : 13
The time server receive order : QUERY TIME ORDER ; the counter is : 14
The time server receive order : QUERY TIME ORDER ; the counter is : 15
The time server receive order : QUERY TIME ORDER ; the counter is : 16
The time server receive order : QUERY TIME ORDER ; the counter is : 17
The time server receive order : QUERY TIME ORDER ; the counter is : 18
The time server receive order : QUERY TIME ORDER ; the counter is : 19
The time server receive order : QUERY TIME ORDER ; the counter is : 20
The time server receive order : QUERY TIME ORDER ; the counter is : 21
The time server receive order : QUERY TIME ORDER ; the counter is : 22
The time server receive order : QUERY TIME ORDER ; the counter is : 23
The time server receive order : QUERY TIME ORDER ; the counter is : 24
The time server receive order : QUERY TIME ORDER ; the counter is : 25
The time server receive order : QUERY TIME ORDER ; the counter is : 26
The time server receive order : QUERY TIME ORDER ; the counter is : 27
The time server receive order : QUERY TIME ORDER ; the counter is : 28
The time server receive order : QUERY TIME ORDER ; the counter is : 29
The time server receive order : QUERY TIME ORDER ; the counter is : 30
The time server receive order : QUERY TIME ORDER ; the counter is : 31
The time server receive order : QUERY TIME ORDER ; the counter is : 32
The time server receive order : QUERY TIME ORDER ; the counter is : 33
The time server receive order : QUERY TIME ORDER ; the counter is : 34
The time server receive order : QUERY TIME ORDER ; the counter is : 35
The time server receive order : QUERY TIME ORDER ; the counter is : 36
The time server receive order : QUERY TIME ORDER ; the counter is : 37
The time server receive order : QUERY TIME ORDER ; the counter is : 38
The time server receive order : QUERY TIME ORDER ; the counter is : 39
The time server receive order : QUERY TIME ORDER ; the counter is : 40
The time server receive order : QUERY TIME ORDER ; the counter is : 41
The time server receive order : QUERY TIME ORDER ; the counter is : 42
The time server receive order : QUERY TIME ORDER ; the counter is : 43
The time server receive order : QUERY TIME ORDER ; the counter is : 44
The time server receive order : QUERY TIME ORDER ; the counter is : 45
The time server receive order : QUERY TIME ORDER ; the counter is : 46
The time server receive order : QUERY TIME ORDER ; the counter is : 47
The time server receive order : QUERY TIME ORDER ; the counter is : 48
The time server receive order : QUERY TIME ORDER ; the counter is : 49
The time server receive order : QUERY TIME ORDER ; the counter is : 50
The time server receive order : QUERY TIME ORDER ; the counter is : 51
The time server receive order : QUERY TIME ORDER ; the counter is : 52
The time server receive order : QUERY TIME ORDER ; the counter is : 53
The time server receive order : QUERY TIME ORDER ; the counter is : 54
The time server receive order : QUERY TIME ORDER ; the counter is : 55
The time server receive order : QUERY TIME ORDER ; the counter is : 56
The time server receive order : QUERY TIME ORDER ; the counter is : 57
The time server receive order : QUERY TIME ORDER ; the counter is : 58
The time server receive order : QUERY TIME ORDER ; the counter is : 59
The time server receive order : QUERY TIME ORDER ; the counter is : 60
The time server receive order : QUERY TIME ORDER ; the counter is : 61
The time server receive order : QUERY TIME ORDER ; the counter is : 62
The time server receive order : QUERY TIME ORDER ; the counter is : 63
The time server receive order : QUERY TIME ORDER ; the counter is : 64
The time server receive order : QUERY TIME ORDER ; the counter is : 65
The time server receive order : QUERY TIME ORDER ; the counter is : 66
The time server receive order : QUERY TIME ORDER ; the counter is : 67
The time server receive order : QUERY TIME ORDER ; the counter is : 68
The time server receive order : QUERY TIME ORDER ; the counter is : 69
The time server receive order : QUERY TIME ORDER ; the counter is : 70
The time server receive order : QUERY TIME ORDER ; the counter is : 71
The time server receive order : QUERY TIME ORDER ; the counter is : 72
The time server receive order : QUERY TIME ORDER ; the counter is : 73
The time server receive order : QUERY TIME ORDER ; the counter is : 74
The time server receive order : QUERY TIME ORDER ; the counter is : 75
The time server receive order : QUERY TIME ORDER ; the counter is : 76
The time server receive order : QUERY TIME ORDER ; the counter is : 77
The time server receive order : QUERY TIME ORDER ; the counter is : 78
The time server receive order : QUERY TIME ORDER ; the counter is : 79
The time server receive order : QUERY TIME ORDER ; the counter is : 80
The time server receive order : QUERY TIME ORDER ; the counter is : 81
The time server receive order : QUERY TIME ORDER ; the counter is : 82
The time server receive order : QUERY TIME ORDER ; the counter is : 83
The time server receive order : QUERY TIME ORDER ; the counter is : 84
The time server receive order : QUERY TIME ORDER ; the counter is : 85
The time server receive order : QUERY TIME ORDER ; the counter is : 86
The time server receive order : QUERY TIME ORDER ; the counter is : 87
The time server receive order : QUERY TIME ORDER ; the counter is : 88
The time server receive order : QUERY TIME ORDER ; the counter is : 89
The time server receive order : QUERY TIME ORDER ; the counter is : 90
The time server receive order : QUERY TIME ORDER ; the counter is : 91
The time server receive order : QUERY TIME ORDER ; the counter is : 92
The time server receive order : QUERY TIME ORDER ; the counter is : 93
The time server receive order : QUERY TIME ORDER ; the counter is : 94
The time server receive order : QUERY TIME ORDER ; the counter is : 95
The time server receive order : QUERY TIME ORDER ; the counter is : 96
The time server receive order : QUERY TIME ORDER ; the counter is : 97
The time server receive order : QUERY TIME ORDER ; the counter is : 98
The time server receive order : QUERY TIME ORDER ; the counter is : 99
The time server receive order : QUERY TIME ORDER ; the counter is : 100

客户端运行结果如下：

"D:\Program Files (x86)\Java\jdk1.8.0_65\bin\java" "-javaagent:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2017.1.4\lib\idea_rt.jar=62637:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2017.1.4\bin" -Dfile.encoding=UTF-8 -classpath "D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\charsets.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\deploy.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\access-bridge-64.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\cldrdata.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\dnsns.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jaccess.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jfxrt.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\localedata.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\nashorn.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunec.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunjce_provider.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunmscapi.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunpkcs11.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\zipfs.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\javaws.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jce.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfr.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfxswt.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jsse.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\management-agent.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\plugin.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\resources.jar;D:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\rt.jar;F:\01_Code\02_Idea\CoreInNetty\target\classes;C:\Users\lsf\.m2\repository\io\netty\netty-all\4.0.32.Final\netty-all-4.0.32.Final.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-core\2.6.3\jackson-core-2.6.3.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-databind\2.6.3\jackson-databind-2.6.3.jar;C:\Users\lsf\.m2\repository\com\fasterxml\jackson\core\jackson-annotations\2.6.0\jackson-annotations-2.6.0.jar" com.hust.grid.leesf.chapter4.correct.TimeClient
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 1
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 2
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 3
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 4
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 5
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 6
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 7
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 8
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 9
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 10
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 11
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 12
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 13
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 14
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 15
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 16
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 17
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 18
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 19
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 20
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 21
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 22
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 23
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 24
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 25
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 26
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 27
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 28
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 29
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 30
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 31
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 32
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 33
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 34
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 35
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 36
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 37
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 38
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 39
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 40
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 41
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 42
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 43
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 44
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 45
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 46
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 47
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 48
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 49
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 50
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 51
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 52
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 53
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 54
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 55
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 56
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 57
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 58
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 59
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 60
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 61
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 62
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 63
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 64
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 65
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 66
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 67
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 68
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 69
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 70
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 71
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 72
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 73
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 74
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 75
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 76
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 77
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 78
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 79
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 80
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 81
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 82
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 83
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 84
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 85
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 86
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 87
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 88
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 89
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 90
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 91
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 92
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 93
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 94
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 95
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 96
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 97
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 98
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 99
Now is : Wed Jun 28 16:12:25 CST 2017 ; the counter is : 100

可以看到此时客户端和服务端的消息发送和接收都已经正常，不存在粘包问题。

　　2.3 LineBasedFrameDecoder和StringDecoder解码器说明

　　LineBasedFrameDecoder会依次遍历ByteBuf中的可读字节，判断是否有\n或者\r\n，其作为一行结束的标志，其是支持以换行符为结束标志的解码器，支持携带结束符和非结束符的两种解码方式，同时支持配置最大单行长度，此时，如果连续读取最大长度后仍未发现换行符，则会抛出异常，并忽略之前读取的数据。

　　StringDecoder将接收的对象转化为字符串，然后继续调用后面的handler，LineBasedFrameDecoder和StringDecoder组合起来使用用来解决按行切换的文本解码器。并且Netty中提供了丰富的解码器和编码器供使用，具体的可以参见官方文档。


三、总结

　　本篇博文讲解了TCP粘包，以及如何通过解码器解决TCP粘包问题，当然，Netty除了提供按行切换的文本解码器之外，还针对不同的应用场景，提供了其他丰富的解码器。谢谢各位园友的观看~

　

文章标签：
云数据库 ClickHouse
网络协议
移动开发
关键词：
Netty tcp
Netty粘包
Netty拆包
tcp/ip协议netty
tcp/ip协议粘包
xleesf
目录
相关文章
流烟默
|
4月前
|
编解码 缓存 移动开发
TCP粘包/拆包与Netty解决方案
TCP粘包/拆包与Netty解决方案
流烟默
45 0
赵广陆
|
7月前
|
移动开发 网络协议 算法
由浅入深Netty粘包与半包解决方案
由浅入深Netty粘包与半包解决方案
赵广陆
50 0
海风极客
|
2月前
|
网络协议
Netty实现TCP通信
Netty实现TCP通信
海风极客
43 0
一只牛博
|
13天前
|
网络协议 Java 物联网
Spring Boot与Netty打造TCP服务端(解决粘包问题)
Spring Boot与Netty打造TCP服务端(解决粘包问题)
一只牛博
26 1
小小工匠
|
3月前
|
编解码
Netty Review - 优化Netty通信：如何应对粘包和拆包挑战_自定义长度分包编解码码器
Netty Review - 优化Netty通信：如何应对粘包和拆包挑战_自定义长度分包编解码码器
小小工匠
46 0
小小工匠
|
3月前
|
网络协议
Netty Review - 优化Netty通信：如何应对粘包和拆包挑战
Netty Review - 优化Netty通信：如何应对粘包和拆包挑战
小小工匠
50 0
岁岁种桃花儿
|
4月前
|
存储 网络协议 算法
Netty使用篇：半包&粘包
Netty使用篇：半包&粘包
岁岁种桃花儿
85 0
waynaqua
|
10月前
|
网络协议
netty编程实战02-创建一个带有连接重试的tcp客户端程序
netty编程实战02-创建一个带有连接重试的tcp客户端程序
waynaqua
159 0
杨宸杨
|
8月前
|
Nacos
Netty自定义消息协议的实现逻辑处理粘包拆包、心跳机制
Netty自定义消息协议的实现逻辑处理粘包拆包、心跳机制
杨宸杨
106 0
杨宸杨
|
8月前
|
存储 编解码 网络协议
Netty各组件基本用法、入站和出站详情、群聊系统的实现、粘包和拆包
Netty各组件基本用法、入站和出站详情、群聊系统的实现、粘包和拆包
杨宸杨
70 0