目录

pom依赖

Server端

main方法初始化netty

服务端端主动给客户端发送消息

pom依赖

		
			io.netty
			netty-all
			4.1.36.Final
		

Server端

package com.kc.monitor.core.utils.netty;
 
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.SimpleChannelInboundHandler;
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;

import java.net.InetSocketAddress;
import java.util.concurrent.ConcurrentHashMap;

public class NettyServer{

    
    public static ConcurrentHashMap userIdMap = new ConcurrentHashMap();

    
    public static ConcurrentHashMap remoteAddressMap = new ConcurrentHashMap();

    
    public static int port = 8081;

    public void initServer() {
        
        // 用于接受客户端连接的请求 （并没有处理请求）
        NioEventLoopGroup bossGroup = new NioEventLoopGroup();
        // 用于处理客户端连接的读写操作，三个线程
        NioEventLoopGroup workGroup = new NioEventLoopGroup(3);

        // 用于创建我们的ServerBootstrap
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap.group(bossGroup, workGroup).channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        // LinebasedframeDecoder解决粘包-解包问题，设置我们分割最大长度为1024
                        // 原理就是自动帮我们把带有n或rn的数据进行换行
                        //socketChannel.pipeline().addLast(new LinebasedframeDecoder(1024));
                        socketChannel.pipeline().addLast(new StringEncoder());// String编码器
                        socketChannel.pipeline().addLast(new StringDecoder());// String解码器
                        socketChannel.pipeline().addLast(new ServerHandler());// 管道类-接收发送消息
                    }
                });

        try {
            // 绑定端口号，同步等待成功
            ChannelFuture future = serverBootstrap.bind(port).sync();
            System.out.println("服务器启动成功：" + port);
            // 等待服务器监听端口
            future.channel().closeFuture().sync();
            System.out.println("关闭服务器");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 优雅的关闭连接
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
 
}
 
 
class ServerHandler extends SimpleChannelInboundHandler {

    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
        // msg消息协议格式：id/消息内容
        String[] split = msg.split("/");
        NettyServer.userIdMap.put(split[0], channelHandlerContext);

        System.out.println("接收客户端消息：" + msg);
        // 响应客户端内容:
        channelHandlerContext.writeAndFlush("00");

        InetSocketAddress ipSocket = (InetSocketAddress)channelHandlerContext.channel().remoteAddress();
        System.out.println("获取客户端ip：" + ipSocket.getAddress().toString());
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // remoteAddress = /192.168.52.1:59807
        String remoteAddress = ctx.channel().remoteAddress().toString();
        System.out.println("有客户端连接... 客户端地址" + remoteAddress);
        NettyServer.remoteAddressMap.put(remoteAddress, ctx);
        super.channelActive(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        String remoteAddress = ctx.channel().remoteAddress().toString();
        System.out.println("有客户端断开连接... " + remoteAddress);
        NettyServer.remoteAddressMap.remove(remoteAddress);
        super.channelInactive(ctx);
    }
}

main方法初始化netty

@SpringBootApplication
@MapperScan(basePackages = "com.kc.monitor.mapper")
public class MonitorApplication {

	public static void main(String[] args) {
		SpringApplication.run(MonitorApplication.class, args);

		// 初始化Netty服务器
		NettyServer nettyServer = new NettyServer();
		nettyServer.initServer();
	}

}

服务端端主动给客户端发送消息

发送前提是以有客户端连接了服务器端。

注意：修改address客户端地址，也可以直接从remoteAddressMap中读取客户端地址。

    
    @GetMapping("/test")
    public void add(String msg){
        System.out.println(NettyServer.remoteAddressMap.size());
        System.out.println(NettyServer.userIdMap.size());

        // 1.根据客户端ip地址发送，发送消息到“/192.168.52.1:59807”客户端
        String address = "/192.168.52.1:59807";
        if (NettyServer.remoteAddressMap.containsKey(address)){
            NettyServer.remoteAddressMap.get(address).writeAndFlush(msg);
        }

        // 2.给用户id为1的客户端发送消息
        String userId = "1";
        if (NettyServer.userIdMap.containsKey(userId)){
            NettyServer.userIdMap.get(userId).writeAndFlush(msg);
        }

    }