Netty读写检测与长连接

使用《Netty多客户端通信》中的客户端代码进行测试，这里实现server端的代码：

MyServer.java

package com.dongqiang.netty.fourthexample;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * Netty读写检测,使用thirdexample中的Client测试
 */
public class MyServer {
    public static void main(String[] args) throws Exception {

        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO)).childHandler(new MyServerInitializer());
            ChannelFuture channelFuture = serverBootstrap.bind("localhost", 8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

这里添加了一个handler()方法，顾名思义，handler是设置在bossGroup的，childHandler()设置给workerGroup。这里打开了日志级别，为INFO。那么启动服务器的时候，会有日志打印出来。

MyServerInitializer.java

package com.dongqiang.netty.fourthexample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.timeout.IdleStateHandler;

import java.util.concurrent.TimeUnit;

/**
 * Created by dongqiang on 2017/6/11.
 */
public class MyServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(5, 7, 10, TimeUnit.SECONDS));
        pipeline.addLast(new MyServerHandler());
    }
}

添加的第二个处理器，是空闲状态处理器，由Netty提供，第一个参数为readerIdleTime（读空闲时间），第二个参数为writerIdleTime（写空闲时间），第三个参数为allIdleTime（读写总空闲时间），第四个参数为unit时间单位。

自定义MyServerHandler处理器：

MyServerHandler.java

package com.dongqiang.netty.fourthexample;

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

/**
 * Created by dongqiang on 2017/6/11.
 */
public class MyServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            IdleState state = event.state();
            String eventType = "";
            switch (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() + "超时事件：" + eventType);
            ctx.channel().close();
        }
    }
}

使用《Netty多客户端通信》客户端代码，然后启动服务端和客户端，然后在客户端不断输入，可以看到写空闲，改小总时间，可以看到读写空闲。所谓读写，都是针对server程序而言。所谓空闲，就是没有读操作或者写操作。