2.Netty - 2.6 Netty开发多人聊天室 - 《Java架构师-2021》

1.server端：

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 ChatServer {
    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup(8);
        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //加入特殊分隔符分包解码器
                            //pipeline.addLast(new DelimiterBasedFrameDecoder(1024, Unpooled.copiedBuffer("_"
                            // .getBytes())));
                            //向pipeline加入解码器
                            pipeline.addLast("decoder", new StringDecoder());
                            //向pipeline加入编码器
                            pipeline.addLast("encoder", new StringEncoder());
                            //加入自己的业务处理handler
                            pipeline.addLast(new ChatServerHandler());
                        }
                    });
            System.out.println("聊天室server启动。。");
            ChannelFuture channelFuture = bootstrap.bind(9000).sync();
            //关闭通道
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

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;
public class ChatServerHandler extends SimpleChannelInboundHandler<String> {
    //GlobalEventExecutor.INSTANCE 是全局的事件执行器，是一个单例
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    //表示 channel 处于就绪状态, 提示上线
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        Channel channel = ctx.channel();
        //将该客户加入聊天的信息推送给其它在线的客户端
        //该方法会将 channelGroup 中所有的 channel 遍历，并发送消息
        channelGroup.writeAndFlush("[ 客户端 ]" + channel.remoteAddress() + " 上线了 " + sdf.format(new
                java.util.Date()) + "\n");
        //将当前 channel 加入到 channelGroup
        channelGroup.add(channel);
        System.out.println(ctx.channel().remoteAddress() + " 上线了" + "\n");
    }
    //表示 channel 处于不活动状态, 提示离线了
    @Override
    public void channelInactive(ChannelHandlerContext ctx) {
        Channel channel = ctx.channel();
        //将客户离开信息推送给当前在线的客户
        channelGroup.writeAndFlush("[ 客户端 ]" + channel.remoteAddress() + " 下线了" + "\n");
        System.out.println(ctx.channel().remoteAddress() + " 下线了" + "\n");
        System.out.println("channelGroup size=" + channelGroup.size());
    }
    //读取数据
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) {
        //获取到当前 channel
        Channel channel = ctx.channel();
        //这时我们遍历 channelGroup, 根据不同的情况， 回送不同的消息
        channelGroup.forEach(ch -> {
            if (channel != ch) { //不是当前的 channel,转发消息
                ch.writeAndFlush("[ 客户端 ]" + channel.remoteAddress() + " 发送了消息：" + msg + "\n");
            } else {//回显自己发送的消息给自己
                ch.writeAndFlush("[ 自己 ]发送了消息：" + msg + "\n");
            }
        });
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        //关闭通道
        ctx.close();
    }
}

2.客户端

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
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 ChatClient {
    public static void main(String[] args) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //pipeline.addLast(new DelimiterBasedFrameDecoder(1024, Unpooled.copiedBuffer("_"
                            // .getBytes())));
                            //向pipeline加入解码器
                            pipeline.addLast("decoder", new StringDecoder());
                            //向pipeline加入编码器
                            pipeline.addLast("encoder", new StringEncoder());
                            //加入自己的业务处理handler
                            pipeline.addLast(new ChatClientHandler());
                        }
                    });
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 9000).sync();
            //得到 channel
            Channel channel = channelFuture.channel();
            System.out.println("========" + channel.localAddress() + "========");
            //客户端需要输入信息， 创建一个扫描器
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()) {
                String msg = scanner.nextLine();
                //通过 channel 发送到服务器端
                channel.writeAndFlush(msg);
            }
            /*for (int i = 0; i < 200; i++) {
                channel.writeAndFlush("hello，诸葛!" + "_");
            }*/
        } finally {
            group.shutdownGracefully();
        }
    }
}

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
public class ChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg){
        System.out.println(msg.trim());
    }
}