Netty-07-群聊系统实现

前言

实例要求

• 编写一个Netty 群聊系统，实现客户端和服务端之间的数据简单通信（非阻塞）
• 实现多人群聊
• 服务器端： 可以检测用户上线，离线，并实现消息的转发
• 客户端：通过channel 可以无阻塞发送消息给其他用户，同时可以接受其他用户发送来的消息（由）服务器转发得到
• 目的 ： 进一步理解Netty 非阻塞网络编程机制

1. 服务端代码

1.1 启动类

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
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 GroupChatServer {

    private int port;
    public GroupChatServer(int port) {
        this.port = port;
    }


    // 编写run 方法，处理客户端请求
    public void run() throws InterruptedException{
        // 创建两个线程组
        NioEventLoopGroup bossGroup = new NioEventLoopGroup(1);
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();

        try{
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG,128)
                    .childOption(ChannelOption.SO_KEEPALIVE,true)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            pipeline.addLast("decoder",new StringDecoder());
                            pipeline.addLast("encoder",new StringEncoder());
                            pipeline.addLast(new GroupChatHandler());
                        }
                    });

            System.out.println("----- netty 服务端启动 -----");

            // 绑定端口
            ChannelFuture channelFuture = serverBootstrap.bind(port).sync();
            // 监听关闭事件
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    // 主方法启动
    public static void main(String[] args) throws InterruptedException {
        GroupChatServer groupChatServer = new GroupChatServer(7000);
        groupChatServer.run();
    }
}

1.2 Handler

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;

// 处理器
public class GroupChatHandler extends SimpleChannelInboundHandler<String> {
    // 定义一个channel组，管理所有的channel
    // GlobalEventExecutor.INSTANCE 是全局事件执行器，是一个单例
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    // 此方法表示连接建立，一旦建立连接就第一个被执行
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        // 该方法会将channelGroup 中所有的channel 遍历，并发送消息而不需要我们自己去遍历
        channelGroup.writeAndFlush("[客户端]" + channel.remoteAddress() + sdf.format(new Date()) + "加入了聊天");
        // 将当前的Channel 加入到 channelGroup
        channelGroup.add(channel);
    }

    // 表示channel 处于活动状态，提示XXX已经上线
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println(ctx.channel().remoteAddress() + " " + sdf.format(new Date()) + "上线了~");
    }

    // 表示channel 断开连接，将xx客户端离开信息推送给当前在线用户
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println(ctx.channel().remoteAddress() + " " + sdf.format(new Date()) + "离线了~");
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        // channel 关闭后会自动remove掉
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[客户端]" + channel.remoteAddress() +" "+ sdf.format(new Date()) + "离开了\n");
        System.out.println("当前channelGroup大小 ：" + channelGroup.size());
    }

    // 读取数据进行消息的转发
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        // 获取当前的channel
        Channel channel = ctx.channel();

        // 遍历channelGroup 根据不同的情况回显不同的消息
        channelGroup.forEach(item -> {
            if (item != channel){
                item.writeAndFlush("[客户]" + channel.remoteAddress() + "发送了消息：" + msg + "\n");
            }else{
                item.writeAndFlush("[自己]发送了消息：" + msg + "\n");
            }
        });
    }

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

2. 客户端代码

2.1 客户端代码

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 GroupChatClient {
    // 属性
    private final String host;
    private final int port;

    public GroupChatClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    // 启动代码
    public void run() throws InterruptedException{
        NioEventLoopGroup eventExecutors = new NioEventLoopGroup();

        try {
            Bootstrap bootstrap = new Bootstrap()
                    .group(eventExecutors)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //加入Handler
                            pipeline.addLast("decoder", new StringDecoder());
                            pipeline.addLast("encoder", new StringEncoder());
                            pipeline.addLast(new GroupChatClientHandler());
                        }
                    });


            // connect 事件
            ChannelFuture channelFuture = bootstrap.connect(host, port).sync();
            // 得到channel,打印本地地址
            Channel channel = channelFuture.channel();
            System.out.println("--------" + channel.localAddress() + "---------");


            // 客户端需要输入信息
            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 + "\r\n");
            }
        }finally {
            eventExecutors.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new GroupChatClient("127.0.0.1",7000).run();
    }
}

2.2 Handler

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

public class GroupChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg.trim());
    }
}

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