基于Netty简单实现群聊系统

先放到gitee上https://gitee.com/henan000/netty
稍后同步到github
NettyServer服务端

package com.whn.text.nettysimple;

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.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class NettyServer {
    public static void main(String[] args) throws Exception {
        //处理连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //处理业务
        EventLoopGroup workGroup = new NioEventLoopGroup();
        try {

            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //配置
            serverBootstrap.group(bossGroup, workGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 128) //任务阻塞队列
                    .childOption(ChannelOption.SO_KEEPALIVE, true) //保持活跃连接
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast("decoder", new StringDecoder());
                            ch.pipeline().addLast("encoder", new StringEncoder());
                            ch.pipeline().addLast(new NettyServerHandler());
                        }
                    });
            System.out.println("服务端准备完毕。。。");
            //绑定端口，生成channelFuture
            ChannelFuture channelFuture = serverBootstrap.bind(6888).sync();
            //对关闭通道监听
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

服务端处理handler

package com.whn.text.nettysimple;

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;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 自定义Handler
 */
public class NettyServerHandler extends SimpleChannelInboundHandler<String> {

    /**
     * 定义channel组，管理channel
     */
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");


    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("【客户端】" + channel.remoteAddress() + "加入群聊" + simpleDateFormat.format(new Date()));
        channelGroup.add(channel);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("【客户端】" + channel.remoteAddress() + "退出群聊" + simpleDateFormat.format(new Date()));
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("客户端上线了：" + ctx.channel().remoteAddress());
    }

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

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, final String msg) throws Exception {
        final Channel channel = ctx.channel();
        channelGroup.forEach(ch -> {
            if (channel != ch) {
                ch.writeAndFlush(simpleDateFormat.format(new Date()) + "客户" + channel.remoteAddress() + "发送消息：" + msg + "\n");
            } else {
                ch.writeAndFlush(simpleDateFormat.format(new Date()) + "自己发送消息：" + msg + "\n");
            }
        });
    }

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

客户端

package com.whn.text.nettysimple;

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;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

import java.util.Scanner;

public class NettyClient {

    public static void main(String[] args) throws Exception {
        EventLoopGroup eventExecutors = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventExecutors)
                    .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("decoder", new StringDecoder());
                            ch.pipeline().addLast("encoder", new StringEncoder());
                            ch.pipeline().addLast(new NettyClientHandler());
                        }
                    });
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 6888).sync();
            System.out.println("客户端准备 ok。。" + channelFuture.channel().localAddress());
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()) {
                String str = scanner.nextLine();
                channelFuture.channel().writeAndFlush(str + "\r\n");
            }
//            channelFuture.channel().closeFuture().sync();
        } finally {
            eventExecutors.shutdownGracefully();
        }
    }
}

客户端处理handler

package com.whn.text.nettysimple;

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

public class NettyClientHandler extends SimpleChannelInboundHandler<String> {

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