Netty心跳机制

知识点

1、学习idleStateHandler

    用来检测会话状态

2、心跳其实就是一个普通的请求，特点数据简单，业务也简单

　　心跳对于服务端来说，定时清除闲置会话inactive(netty5) channelclose(netty3)

　　心跳对客户端来说，用来检测会话是否断开，是否重连！ 用来检测网络延时！

###################Netty3心跳实现####################

1、Netty3ServerHeart.java

package com.example.netty.lesson7.netty3;

import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
import org.jboss.netty.handler.timeout.IdleStateHandler;
import org.jboss.netty.util.HashedWheelTimer;
/**
 * @author yangwj
 * @date 2020/4/4 23:06
 */
public class Netty3ServerHeart {

    public static void main(String[] args) {

        //服务类
        ServerBootstrap bootstrap = new ServerBootstrap();

        //boss线程监听端口，worker线程负责数据读写
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService worker = Executors.newCachedThreadPool();

        //设置niosocket工厂
        bootstrap.setFactory(new NioServerSocketChannelFactory(boss, worker));

        final HashedWheelTimer hashedWheelTimer = new HashedWheelTimer();
        //设置管道的工厂
        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {

            @Override
            public ChannelPipeline getPipeline() throws Exception {

                ChannelPipeline pipeline = Channels.pipeline();
                //IdleStateHandler设置心跳时间
                pipeline.addLast("idle", new IdleStateHandler(hashedWheelTimer, 5, 5, 10));
                pipeline.addLast("decoder", new StringDecoder());
                pipeline.addLast("encoder", new StringEncoder());
                pipeline.addLast("helloHandler", new HelloHandler());
                return pipeline;
            }
        });

        bootstrap.bind(new InetSocketAddress(51503));

        System.out.println("start!!!");

    }

}

2、HelloHandler.java

package com.example.netty.lesson7.netty3;

import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.handler.timeout.IdleState;
import org.jboss.netty.handler.timeout.IdleStateEvent;

/**
 * @author yangwj
 * @date 2020/4/4 23:08
 * 注意 IdleStateAwareChannelHandler的使用
 */
public class HelloHandler extends SimpleChannelHandler {

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        System.out.println(e.getMessage());
    }

    @Override
    public void handleUpstream(final ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
        if (e instanceof IdleStateEvent) {
            if(((IdleStateEvent)e).getState() == IdleState.ALL_IDLE){
                System.out.println("踢玩家下线");
                //关闭会话,踢玩家下线
                ChannelFuture write = ctx.getChannel().write("time out, you will close");
                write.addListener(new ChannelFutureListener() {
                    @Override
                    public void operationComplete(ChannelFuture future) throws Exception {
                        ctx.getChannel().close();
                    }
                });
            }
        } else {
            super.handleUpstream(ctx, e);
        }
    }

}

#############Netty5心跳实现###############

1、Server.java

package com.example.netty.lesson7.netty5;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;

/**
 * netty5服务端
 * @author yangwj
 *
 */
public class Server {

    public static void main(String[] args) {
        //服务类
        ServerBootstrap bootstrap = new ServerBootstrap();
        
        //boss和worker
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();
        
        try {
            //设置线程池
            bootstrap.group(boss, worker);
            
            //设置socket工厂、
            bootstrap.channel(NioServerSocketChannel.class);
            
            //设置管道工厂
            bootstrap.childHandler(new ChannelInitializer<Channel>() {

                @Override
                protected void initChannel(Channel ch) throws Exception {
                    //IdleStateHandler 心跳设置
                    ch.pipeline().addLast(new IdleStateHandler(5, 5, 10));
                    ch.pipeline().addLast(new StringDecoder());
                    ch.pipeline().addLast(new StringEncoder());
                    ch.pipeline().addLast(new ServerHandler());
                }
            });
            
            //netty3中对应设置如下
            //bootstrap.setOption("backlog", 1024);
            //bootstrap.setOption("tcpNoDelay", true);
            //bootstrap.setOption("keepAlive", true);
            //设置参数，TCP参数
            bootstrap.option(ChannelOption.SO_BACKLOG, 2048);//serverSocketchannel的设置，链接缓冲池的大小
            bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);//socketchannel的设置,维持链接的活跃，清除死链接
            bootstrap.childOption(ChannelOption.TCP_NODELAY, true);//socketchannel的设置,关闭延迟发送
            
            //绑定端口
            ChannelFuture future = bootstrap.bind(51503);
            
            System.out.println("start");
            
            //等待服务端关闭
            future.channel().closeFuture().sync();
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            //释放资源
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

2、ServerHandler.java

package com.example.netty.lesson7.netty5;

import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
/**
 * 服务端消息处理
 * @author yangwj
 *
 */
public class ServerHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void messageReceived(ChannelHandlerContext ctx, String msg) throws Exception {

        System.out.println(msg);
        
        ctx.channel().writeAndFlush("hi");
        ctx.writeAndFlush("hi");
    }


    /**
     * 观测客户端连接状态
     * @param ctx
     * @param evt
     * @throws Exception
     */
    @Override
    public void userEventTriggered(final ChannelHandlerContext ctx, Object evt) throws Exception {
        if(evt instanceof IdleStateEvent){
            IdleStateEvent event = (IdleStateEvent)evt;
            if(event.state() == IdleState.ALL_IDLE){
                //清除超时会话
                ChannelFuture writeAndFlush = ctx.writeAndFlush("you will close");
                writeAndFlush.addListener((ChannelFutureListener)(ChannelFuture future)->{
                    ctx.channel().close();
                });
//                writeAndFlush.addListener(new ChannelFutureListener() {
//                    @Override
//                    public void operationComplete(ChannelFuture future) throws Exception {
//                        ctx.channel().close();
//                    }
//                });
            }
        }else{
            super.userEventTriggered(ctx, evt);
        }
    }


    /**
     * 新客户端接入
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelActive");
    }

    /**
     * 客户端断开
     */
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelInactive");
    }

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

完毕，供自学！