4 Netty多客户端连接与通信 – 小飞侠

4 Netty多客户端连接与通信

Post author:xfxia
Post published:2023年7月19日
Post category:其他

1 Netty多客户端连接与通信

	前言 上篇写到netty的socket简单的例子，这里将上篇的例子改一改，来分析多客户端
连接与通信的情况。下面还是直接上代码。

1.1 服务端

1.1.1 MyServer

package netty.server;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class MyServer {
    public static void main(String[] args) {
        EventLoopGroup boosGourp = new NioEventLoopGroup();
        EventLoopGroup WorkerGourp = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(boosGourp, WorkerGourp).channel(NioServerSocketChannel.class)
                    .childHandler(new MyServerInitializer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            boosGourp.shutdownGracefully();
            WorkerGourp.shutdownGracefully();
        }
    }
}

1.1.2 MyServerInitializer

package netty.server;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;


public class MyServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyServerHandler());
    }
}

1.1.3 MyServerInitializer

package netty.server;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;

public class MyServerHandler extends SimpleChannelInboundHandler<String> {

    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        // 当前通道
        Channel channel = ctx.channel();
        channelGroup.forEach(ch -> {
            if (channel != ch) {
                // 不是当前的通道
                ch.writeAndFlush("[" + channel.remoteAddress() + "]"+":" + msg + "\n");
            } else {
                // 当前的通道
                channel.writeAndFlush("[自己]:" + msg + "\n");
            }
        });
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[服务器]-" + channel.remoteAddress() + "加入\n");
        channelGroup.add(channel);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[服务器]-" + channel.remoteAddress() + "离线\n");
        //channelGroup.remove(channel);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress() + "上线");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress() + "下线");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

1.2 客户端

1.2.1 MyClient

package netty.client;

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

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class MyClient {

    public static void main(String[] args) {
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .handler(new MyClientInitializer());

            Channel channel = bootstrap.connect("localhost", 8899).sync().channel();
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            // 死循环 读取控制台信息
            for (;;){
                channel.writeAndFlush(br.readLine()+"\r\n");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

1.2.2 MyClientInitializer

package netty.client;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyClientInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyClientHandler());
    }
}

1.2.3 MyClientHandler

package netty.client;

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

public class MyClientHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }

}

1.3 分析

1.3.1 演示日志

****************服务段***********************
15:50:47: Executing task 'MyServer.main()'...

> Task :compileJava UP-TO-DATE
> Task :processResources NO-SOURCE
> Task :classes UP-TO-DATE

> Task :MyServer.main()
/127.0.0.1:61245上线
/127.0.0.1:61381上线
/127.0.0.1:61419上线

****************客户段(1)***********************
15:50:57: Executing task 'MyClient.main()'...

Starting Gradle Daemon...
Gradle Daemon started in 2 s 276 ms
> Task :compileJava UP-TO-DATE
> Task :processResources NO-SOURCE
> Task :classes UP-TO-DATE
> Task :MyClient.main()
[服务器]-/127.0.0.1:61381加入
[服务器]-/127.0.0.1:61419加入
客户端一你好
[自己]:客户端一你好
[/127.0.0.1:61419]:客户端你�?
[/127.0.0.1:61419]:客户端三你好
****************客户段(2)***********************
15:51:53: Executing task 'MyClient.main()'...

Starting Gradle Daemon...
Gradle Daemon started in 2 s 249 ms
> Task :compileJava UP-TO-DATE
> Task :processResources NO-SOURCE
> Task :classes UP-TO-DATE

> Task :MyClient.main()
[服务器]-/127.0.0.1:61419加入
[/127.0.0.1:61245]:客户端一你好
****************客户段(3)***********************
15:51:57: Executing task 'MyClient.main()'...

Starting Gradle Daemon...
Gradle Daemon started in 2 s 756 ms
> Task :compileJava UP-TO-DATE
> Task :processResources NO-SOURCE
> Task :classes UP-TO-DATE

> Task :MyClient.main()
[/127.0.0.1:61245]:客户端一你好
客户端3你好
[自己]:客户端你�?
客户端三你好
[自己]:客户端三你好

1.3.2 查看tcp连接情况

C:\Users\Administrator>netstat -ano | findstr "8899"
  TCP    0.0.0.0:8899           0.0.0.0:0              LISTENING       15832
  TCP    127.0.0.1:8899         127.0.0.1:61245        ESTABLISHED     15832
  TCP    127.0.0.1:8899         127.0.0.1:61381        ESTABLISHED     15832
  TCP    127.0.0.1:8899         127.0.0.1:61419        ESTABLISHED     15832
  TCP    127.0.0.1:61245        127.0.0.1:8899         ESTABLISHED     21500
  TCP    127.0.0.1:61381        127.0.0.1:8899         ESTABLISHED     16544
  TCP    127.0.0.1:61419        127.0.0.1:8899         ESTABLISHED     19940
  TCP    192.168.2.140:58899    182.138.81.22:31895    ESTABLISHED     9700
  TCP    [::]:8899              [::]:0                 LISTENING       15832

1.3.23 总结

ChannelGroup就是一个set集合，保存对应的通道，在接受对应的信息，做到广播的效果。

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原文链接：https://blog.csdn.net/qq_42641261/article/details/109312282