netty学习笔记6-netty实现心跳检测

需求：

使用netty完成系统心跳

编写步骤:

1. 编写服务器启动程序

package com.baidu.netty.fiveExample;

import com.sun.security.ntlm.Server;
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 MyServer {
    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class).childHandler(new MyServerInitializer());
            ChannelFuture future = bootstrap.bind(8899).sync();
            future.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2. 编写服务器端初始化程序

package com.baidu.netty.fiveExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.CharsetUtil;

public class MyServerInitializer extends ChannelInitializer {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(4,5,10));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyServerHandler());
    }
}

3. 编写服务器端处理程序

package com.baidu.netty.fiveExample;

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

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

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

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if(evt instanceof IdleStateEvent)
        {
            IdleStateEvent event = (IdleStateEvent)evt;
            switch (event.state())
            {
                case READER_IDLE:
                    System.out.println("读空闲");
                    break;
                case WRITER_IDLE:
                    System.out.println("写空闲");
                    break;
                case ALL_IDLE:
                System.out.println("读写空闲");
            }
        }
    }
}