基于netty实现一个简单的群聊系统

server 端代码

import com.chinadaas.bio.chinadaasbio.groupChart.handler.ServerHandler;
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.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class Server {

    private Integer PORT;

    public Server(Integer PORT) {
        this.PORT = PORT;
    }

    public void run() {
        NioEventLoopGroup boosGroup = new NioEventLoopGroup(1);
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(boosGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true)
                    .childHandler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            // 加入解码器
                            pipeline.addLast("myDecoder", new StringDecoder());
                            // 加入编码器
                            pipeline.addLast("myEncoder", new StringEncoder());
                            pipeline.addLast(new ServerHandler());
                        }
                    });
            ChannelFuture channelFuture = serverBootstrap.bind(PORT).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            boosGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) {
        Server server = new Server(8886);
        server.run();
    }


}

client端代码

import com.chinadaas.bio.chinadaasbio.groupChart.handler.ClientHandler;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

import java.util.Scanner;

public class Client {

    private final String HOST;
    private final Integer PORT;

    public Client(String host, Integer port) {
        this.HOST = host;
        this.PORT = port;
    }
    public void run() {
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(workerGroup)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            // 解码器
                            pipeline.addLast("myDecoder", new StringDecoder());
                            // 编码器
                            pipeline.addLast("myEncoder", new StringEncoder());
                            pipeline.addLast(new ClientHandler());
                        }
                    });
            ChannelFuture channelFuture = bootstrap.connect(HOST, PORT).sync();
            Channel channel = channelFuture.channel();
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()) {
                String msg = scanner.nextLine();
                channel.writeAndFlush(msg + "\r\n");
            }
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            workerGroup.shutdownGracefully();
        }
    }
    public static void main(String[] args) {
        Client client = new Client("127.0.0.1", 8886);
        client.run();
    }
}

ServerHandler 代码

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 ServerHandler extends SimpleChannelInboundHandler {

    /**
     * GlobalEventExecutor.INSTANCE 全局事件执行器
     * */
    private static final ChannelGroup CHANNEL_GROUP = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

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

    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println(ctx.channel() + "离线了");
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        CHANNEL_GROUP.writeAndFlush("[客户端]" + channel.remoteAddress() + "加入群聊");
        CHANNEL_GROUP.add(channel);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        CHANNEL_GROUP.writeAndFlush("[客户端]" + channel.remoteAddress() + "离开群聊");
    }

    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {
        // 获取消息并转发到群聊中其他的人
        Channel channel = channelHandlerContext.channel();
        CHANNEL_GROUP.forEach(ch -> {
            if (ch != channel) {
                ch.writeAndFlush("[客户" + channel.remoteAddress() + "]说:" + s + "\n");
            } else {
                ch.writeAndFlush("我说：" + s + "\n");
            }
        });
    }

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

ClientHandler 代码

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

public class ClientHandler extends SimpleChannelInboundHandler {


    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {
        System.out.println(s.trim());
    }

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

后面还有优化，当前只是大致实现以下