Netty 示例3 聊天室

需求一：C上线通知A、B，C上线了，但是没必要通知C。
需求二：自己发出去的消息看到发消息人是“自己”。

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 MyChatServer {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                    .childHandler(new MyChatServerInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

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 MyChatServerInitializer extends ChannelInitializer {
    @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 MyChatServerHandler());
    }
}

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 MyChatServerHandler extends SimpleChannelInboundHandler {
    // 保存channel对象
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        // 使用channelGroup简化广播
        channelGroup.writeAndFlush("[服务器] - " + channel.remoteAddress() + " 加入\n");
        // 先广播再添加，保证新上线的不接收广播的消息：A和B收到，新上线的C不收到
        channelGroup.add(channel);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        // 给服务端自己看
        System.out.println(channel.remoteAddress() + " 上线");
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.forEach(ch -> {
            if (channel == ch) {
                ch.writeAndFlush("[自己]：" + msg + "\n");
            } else {
                ch.writeAndFlush("[" + channel.remoteAddress() + "]：" + msg +"\n");
            }
        });
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        // 给服务端自己看
        System.out.println(channel.remoteAddress() + " 下线");
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        // 会自动删除断掉的channel，断掉的channel也不会收到广播
        channelGroup.writeAndFlush("[服务器] - " + channel.remoteAddress() + " 离开\n");
    }


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

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.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

public class MyChatClient {
    public static void main(String[] args) throws InterruptedException, IOException {
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    // 客户端只有一个eventLoopGroup，所以不需要用childHandler
                    .handler(new MyChatClientInitializer());

            // 在这里发送，在MyChatClientHandler中接收服务端的返回
            Channel channel = bootstrap.connect("localhost", 8899).sync().channel();
            Scanner scan = new Scanner(System.in);
            while (scan.hasNext()) {
                channel.writeAndFlush(scan.next() + "\r\n");
            }
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

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 MyChatClientInitializer extends ChannelInitializer {

    @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 MyChatClientHandler());
    }
    
}

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

public class MyChatClientHandler extends SimpleChannelInboundHandler{
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        // 客户端简单接收服务端传来的消息就行了，输入消息在MyChatClient中
        System.out.println(msg);
    }
}