Netty（三）TCP粘包与拆包

作者: 南园故剑00 | 来源:发表于2020-06-08 17:30 被阅读0次

package com.sgg.tcp.protocol;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

/**
 * @description:
 * @date : 2020/6/7 19:00
 * @author: zwz
 */
public class NettyClient {
    public static void main(String[] args) throws InterruptedException {
        //客户端需要一个事件循环组
        EventLoopGroup eventExecutors = new NioEventLoopGroup();

        //创建客户端启动对象
        Bootstrap bootstrap = new Bootstrap();

        try {
            bootstrap.group(eventExecutors)  //设置线程组
                    .channel(NioSocketChannel.class)  //设置客户端通道的实现类
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new MyMessageToByteEncoder())
                                    .addLast(new MyMessageToByteDecoder())
                                    .addLast(new NettyClientHandler());  //加入自己的处理器
                        }
                    });
            System.out.println("客户端 ok...");
            //启动客户端去连接服务器端
            //涉及到netty的异步模型
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 6668).sync();
            //给关闭通道进行监听
            channelFuture.channel().closeFuture().sync();
        } finally {
            eventExecutors.shutdownGracefully();
        }
    }
}

package com.sgg.tcp.protocol;

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

/**
 * @description: 自定义一个Handler 需要继续 netty 绑定好的某个 HandlerAdapter
 * @date : 2020/6/7 18:44
 * @author: zwz
 */
public class NettyClientHandler extends SimpleChannelInboundHandler<MessageProtocol> {

    private int count;

    /**
     * 当通道就绪就会触发该方法
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("client " + ctx);
        for (int i = 0; i < 5; ++i) {
            String mes = "今天天气冷，吃火锅";
            byte[] context = mes.getBytes(CharsetUtil.UTF_8);

            //创建协议包对象
            MessageProtocol messageProtocol = new MessageProtocol();
            messageProtocol.setLen(context.length);
            messageProtocol.setContent(context);
            ctx.writeAndFlush(messageProtocol);
        }
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, MessageProtocol msg) throws Exception {
        //接收到数据并处理
        int len = msg.getLen();
        byte[] content = msg.getContent();
        System.out.println("客户端接收的消息如下");
        System.out.println("长度=" + len);
        System.out.println("内容" + new String(content, CharsetUtil.UTF_8));
        System.out.println("客户端接收到的消息数量=" + (++this.count));
    }

    //处理异常 需要关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

package com.sgg.tcp.protocol;

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;

/**
 * @description:
 * @date : 2020/6/7 18:23
 * @author: zwz
 */
public class NettyServer {
    public static void main(String[] args) throws InterruptedException {
        //创建BossGroup和WorkerGroup
        //1. 创建两个线程组
        //2. bossGroup只是处理连接请求，真正的和客户端业务处理，会交给workerGroupo完成
        //3. 两个都是无限循环
        //4. bossGroup 和 workGroup 含有的子线程的个数
        //默认实际 CPU 核数*2=8。在不传参数的情况下有8个 线程。我的24个线程
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        //创建服务器端的启动对象，配置参数
        ServerBootstrap bootstrap = new ServerBootstrap();
        try {
            //使用链式编程设置
            bootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)  //使用NioServerSocketChannel作为服务器的通道实现
                    .option(ChannelOption.SO_BACKLOG, 128) //设置线程队列的连接个数
                    .childHandler(new ChannelInitializer<SocketChannel>() { //创建一个通道测试对象-匿名对象
                        //给pipeline设置处理器
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            //可以使用一个集合管理 socketChannel，再推送消息，
                            // 可以将业务加入到各个 channel 对应的 NIOEventLoop 的 taskQueue 或者 ScheduleTaskQueue
                            System.out.println("客户 socketChannel hashCode=" + ch.hashCode());
                            ch.pipeline().addLast(new MyMessageToByteDecoder())  //编解码器在前。否则会数据传输
                                    .addLast(new MyMessageToByteEncoder())
                                    .addLast(new NettyServerHandler());
                        }
                    }); //给我们的 workerGroup 的EventLoop对应的管道设置处理器

            System.out.println("服务器准备好了");

            //绑定一个端口并同步，生成一个 ChannelFuture 对象
            //启动服务器
            ChannelFuture future = bootstrap.bind(6668).sync();

            //对关闭通道进行监听
            future.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

package com.sgg.tcp.protocol;

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

import java.nio.charset.StandardCharsets;
import java.util.UUID;

/**
 * @description: 自定义一个Handler 需要继续 netty 绑定好的某个 HandlerAdapter
 * @date : 2020/6/7 18:44
 * @author: zwz
 */
public class NettyServerHandler extends SimpleChannelInboundHandler<MessageProtocol> {

    private int count;

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, MessageProtocol msg) throws Exception {
        //接收到数据并处理
        int len = msg.getLen();
        byte[] content = msg.getContent();
        System.out.println("\n\n");
        System.out.println("服务器接收到的信息如下  ");
        System.out.println("长度=" + len);
        System.out.println("内容=" + new String(content, CharsetUtil.UTF_8));
        System.out.println("服务器接收到的消息包数量" + (++count));

        //回复的消息
        String responseContent = UUID.randomUUID().toString();
        byte[] bytes = responseContent.getBytes(StandardCharsets.UTF_8);
        MessageProtocol messageProtocol = new MessageProtocol();
        messageProtocol.setLen(bytes.length);
        messageProtocol.setContent(bytes);
        System.out.println("回复的消息:" + responseContent);
        ctx.writeAndFlush(messageProtocol);
    }

    //处理异常 需要关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

package com.sgg.tcp.protocol;

/**
 * @description: 协议包
 * @date : 2020/6/8 21:06
 * @author: zwz
 */
public class MessageProtocol {

    private int len;

    private byte[] content;

    public int getLen() {
        return len;
    }

    public void setLen(int len) {
        this.len = len;
    }

    public byte[] getContent() {
        return content;
    }

    public void setContent(byte[] content) {
        this.content = content;
    }
}

package com.sgg.tcp.protocol;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;

import java.util.List;

/**
 * @description:
 * @date : 2020/6/8 21:13
 * @author: zwz
 */
public class MyMessageToByteDecoder extends ReplayingDecoder<Void> {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        System.out.println("MyMessageToByteDecoder decode 方法被调用" );
        //需要将得到的二进制字节码 转换为 MessageProtocol 数据包（对象）
        int length = in.readInt();  //这里读取的实际就是  MessageProtocol 中的 len 字段（在handler中指定了就是消息的字节数组长度）
        byte[] context = new byte[length];
        in.readBytes(context);

        //封装成 MEssageProtocol 对象，放入 out，传递下一个 handler 业务处理
        MessageProtocol messageProtocol = new MessageProtocol();
        messageProtocol.setLen(length);
        messageProtocol.setContent(context);

        out.add(messageProtocol);
    }
}

package com.sgg.tcp.protocol;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

/**
 * @description:
 * @date : 2020/6/8 21:13
 * @author: zwz
 */
public class MyMessageToByteEncoder extends MessageToByteEncoder<MessageProtocol> {

    @Override
    protected void encode(ChannelHandlerContext ctx, MessageProtocol msg, ByteBuf out) throws Exception {
        System.out.println("MyMessageEncorder encode 方法被调用" );
        out.writeInt(msg.getLen());
        out.writeBytes(msg.getContent());
    }
}

Netty（三）TCP粘包与拆包

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