Netty心跳检测机制

主要是用于服务端检测,客户端不显示 

1. 服务端

import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.IdleStateHandler;

import java.util.concurrent.TimeUnit;

public class MyServer {
    public static void main(String[] args) throws InterruptedException {
        NioEventLoopGroup boss = new NioEventLoopGroup();
        NioEventLoopGroup worker = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(boss, worker)
                    .channel(NioServerSocketChannel.class)
                    //为boss添加日志
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            /**
                             * IdleStateHandler(  处理空闲状态的处理类
                             long readerIdleTime,  表示在时间内未读,发送一个心跳检测包来检测是否连接
                             long writerIdleTime,   表示在时间内未写,发送一个心跳检测包来检测是否连接
                             long allIdleTime,      表示在时间内没有读写,发送一个心跳检测包来检测是否连接
                             TimeUnit unit)``````` 单位
                             当IdleStateHandler触发后,传递给管道下一个handler处理,通过调用下一个handler的userEventTiggered,
                             在该方法中去处理
                             */
                            pipeline.addLast(new IdleStateHandler(3, 5, 7, TimeUnit.SECONDS));
                            //自定义对空闲检测进一步处理的handler
                            pipeline.addLast(new MyServerHandler());
                        }
                    });
            //启动服务,绑定端口
            ChannelFuture channelFuture = serverBootstrap.bind(7000).sync();
            //监控关闭端口
            channelFuture.channel().closeFuture().sync();
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();

        }
    }
}

2.服务端处理类

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleStateEvent;

//事件处理类
public class MyServerHandler extends ChannelInboundHandlerAdapter {
    /**
     * @param ctx 上下文
     * @param evt 事件
     */
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            String eventType = null;
            switch (event.state()) {
                case READER_IDLE:
                    eventType = "读空闲";
                    break;
                case WRITER_IDLE:
                    eventType = "写空闲";
                    break;
                case ALL_IDLE:
                    eventType = "读写空闲";
                    break;
            }
            System.out.println(ctx.channel().remoteAddress()+":"+eventType);
        }
    }
}

3.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 Client {
    private final String hostname;
    private final int port;

    public Client(String hostname, int port) {
        this.hostname = hostname;
        this.port = port;
    }

    public void run() throws InterruptedException {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            //客户端启动项
            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();
                            //解码器
                            pipeline.addLast("Decoder", new StringDecoder());
                            //编码器
                            pipeline.addLast("Encoder", new StringEncoder());
                            pipeline.addLast(new ClientHandler());
                        }
                    });
            //启动客户端去连接服务器端
            ChannelFuture channelFuture = bootstrap.connect(hostname, port).sync();
            //得到channel
            Channel channel = channelFuture.channel();
            System.out.println("-------" + channel.localAddress() + "-------");
            //客户输入信息
            Scanner sc = new Scanner(System.in);
            while (sc.hasNextLine()) {
                String msg = sc.nextLine();
                channel.writeAndFlush(msg + "
");
            }
        } finally {
            group.shutdownGracefully();
        }
    }

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

4.客户端处理类

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

public class ClientHandler extends SimpleChannelInboundHandler<String>{

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        //输出去除两端空格的字符串
        System.out.println(msg.trim());
    }
}