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Netty（三）之数据之粘包拆包

数据
2023-03-14 22:58:02 时间

前提


Netty（一）之helloworld


数据的粘包


在上面的的例子基础之上的TimeClient上修改


我们的本意是发送三条您好


 //发送数据
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);//防止TCP粘包
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);


4.png


数据粘在一起了，就是数据的粘包


初步解决办法


   //发送数据
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            Thread.sleep(1000);//防止TCP粘包
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            Thread.sleep(1000);
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            Thread.sleep(1000);


分隔符解码DelimiterBasedFrameDceoder


TimeServerHandler


package mydelimiterBasedFrameDecoder;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:31
 */
public class TimeServerHandler extends ChannelHandlerAdapter {
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
 
        //服务器读客户端发送来的数据
        String body = (String) msg;//之所以能强制类型转换是因为添加了StringDecoder
        System.out.println("The TimeServer receive :" + body);
 
        //服务器向客户端回应请求
        String resp = "服务器端已经收到客户端数据$_";//$_结尾符号
        ByteBuf response = Unpooled.copiedBuffer(resp.getBytes());
        ctx.writeAndFlush(response);
 
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
 
//
}


TimeServer


package mydelimiterBasedFrameDecoder;
 
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:22
 */
public class TimeServer {
 
 
    public static void main(String[] args) throws Exception {
        int port = 8080;
        //配置服务器端的NIO线程组
        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 ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //设置特殊分隔符
                            ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());
                            socketChannel.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));
                            //设置字符串编码器，使其在handler中的msg可以直接强转为String
                            socketChannel.pipeline().addLast(new StringDecoder());
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeServerHandler());
                        }
                    });
            //绑定端口
            ChannelFuture f = b.bind(port).sync();
            //等待服务端监听端口关闭
            f.channel().closeFuture().sync();
 
 
        } catch (Exception e) {
 
        } finally {
            //优雅关闭，释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}


TimeClientHandler


package mydelimiterBasedFrameDecoder;
 
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:47
 */
public class TimeClientHandler extends ChannelHandlerAdapter {
 
 
    //客户端读取服务器发送的数据
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
 
            String body = (String) msg;
            System.out.println("Now is:" + body);
        } catch (Exception e) {
 
        } finally {
            //标配
            ReferenceCountUtil.release(msg);
        }
 
 
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
}


TimeClient


package mydelimiterBasedFrameDecoder;
 
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:43
 */
public class TimeClient {
 
 
    public static void main(String[] args) throws Exception {
        int port = 8080;
        String host = "127.0.0.1";
        //配置客户端NIO线程组
        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
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //设置特殊分隔符
                            ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());
                            socketChannel.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));
                            //设置字符串编码器，使其在handler中的msg可以直接强转为String
                            socketChannel.pipeline().addLast(new StringDecoder());
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            //发起异步连接操作
            ChannelFuture f = b.connect(host, port).sync();
 
 
            //发送数据
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好$_".getBytes()));
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好$_".getBytes()));
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好$_".getBytes()));
 
 
            //等待客户端链路关闭
            f.channel().closeFuture().sync();
 
        } catch (Exception e) {
 
        } finally {
            //优雅关闭
            group.shutdownGracefully();
        }
    }
}


运行结果


5.png


6.png


定长解码器FixedLengthFrameDecoder


TimeServerHandler


读取数据，相应请求


package myfixedlengthframedecoder;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:31
 */
public class TimeServerHandler extends ChannelHandlerAdapter {
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
 
        //服务器读客户端发送来的数据
 
        String body = (String) msg;
        System.out.println("The TimeServer receive :" + body);
 
        //服务器向客户端回应请求
        ByteBuf response = Unpooled.copiedBuffer("1234".getBytes());
        ctx.writeAndFlush(response);
 
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
 
//
}


TimeServer


添加定长解码器


添加字符串解码器


package myfixedlengthframedecoder;
 
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;
import io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:22
 */
public class TimeServer {
 
 
    public static void main(String[] args) throws Exception {
        int port = 8080;
        //配置服务器端的NIO线程组
        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 ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //添加固定长度解码器， 固定长度为5
                            socketChannel.pipeline().addLast(new FixedLengthFrameDecoder(5));
                            socketChannel.pipeline().addLast(new StringDecoder());
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeServerHandler());
                        }
                    });
            //绑定端口
            ChannelFuture f = b.bind(port).sync();
            //等待服务端监听端口关闭
            f.channel().closeFuture().sync();
 
 
        } catch (Exception e) {
 
        } finally {
            //优雅关闭，释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}


TimeClientHandler

接收服务器发来的数据

package myfixedlengthframedecoder;
 
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:47
 */
public class TimeClientHandler extends ChannelHandlerAdapter {
 
 
    //客户端读取服务器发送的数据
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
 
            String body = (String) msg;
            System.out.println("Now is:" + body);
        } catch (Exception e) {
 
        } finally {
            //标配
            ReferenceCountUtil.release(msg);
        }
 
 
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
}


TimeClient


添加定长解码器


添加字符串解码器


发送长度为10的数据（定长解码器设置长度为5）


package myfixedlengthframedecoder;
 
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
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.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
 
/**
 * @author CBeann
 * @create 2019-08-27 18:43
 */
public class TimeClient {
 
 
    public static void main(String[] args) throws Exception {
        int port = 8080;
        String host = "127.0.0.1";
        //配置客户端NIO线程组
        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
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new FixedLengthFrameDecoder(5));
                            socketChannel.pipeline().addLast(new StringDecoder());
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            //发起异步连接操作
            ChannelFuture f = b.connect(host, port).sync();
 
 
            //发送数据
            f.channel().writeAndFlush(Unpooled.copiedBuffer("0123456789".getBytes()));
 
 
 
            //等待客户端链路关闭
            f.channel().closeFuture().sync();
 
        } catch (Exception e) {
 
        } finally {
            //优雅关闭
            group.shutdownGracefully();
        }
    }
}


运行结果


客户端发送10个长度的字符串，因为设置了长度为5的定长解码器，所以服务器收到2条消息


7.png

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