Netty中的Idle事件

Netty中的Idle事件

网络连接中，处理Idle事件是很常见的，比如在mqtt服务中，客户端与服务端在指定时间内没有任何读写请求，就会认为连接是idle的，此时，客户端在指定的idle时间内没有向服务端发送ping消息，服务端可以断开与客户端的链接。

下面的代码演示了在netty中如何设置idle事件。

 

import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;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.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.handler.timeout.IdleState;import io.netty.handler.timeout.IdleStateEvent;import io.netty.handler.timeout.IdleStateHandler;public class NettyTest {public static void main(String[] args) throws InterruptedException {    EventLoopGroup bossGroup = new NioEventLoopGroup();     EventLoopGroup workerGroup = new NioEventLoopGroup();    try {        ServerBootstrap b = new ServerBootstrap();        b.group(bossGroup, workerGroup)         .channel(NioServerSocketChannel.class)         .childHandler(new ChannelInitializer<SocketChannel>() {        private static final int IDEL_TIME_OUT = 10;            private static final int READ_IDEL_TIME_OUT = 4;        private static final int WRITE_IDEL_TIME_OUT = 5;             @Override             public void initChannel(SocketChannel ch) throws Exception {         ch.pipeline().addLast("idleStateHandler", new IdleStateHandler(READ_IDEL_TIME_OUT, WRITE_IDEL_TIME_OUT, IDEL_TIME_OUT));                ch.pipeline().addLast(new ChannelInboundHandlerAdapter(){                @Override                public void userEventTriggered(                ChannelHandlerContext ctx, Object evt)                throws Exception {                if(IdleStateEvent.class.isAssignableFrom(evt.getClass())){                IdleStateEvent event = (IdleStateEvent) evt;                if(event.state() == IdleState.READER_IDLE)                System.out.println("read idle");                else if(event.state() == IdleState.WRITER_IDLE)                System.out.println("write idle");                else if(event.state() == IdleState.ALL_IDLE)                System.out.println("all idle");                }                }                });             }         })         .option(ChannelOption.SO_BACKLOG, 128)         .childOption(ChannelOption.SO_KEEPALIVE, true);                ChannelFuture f = b.bind(8080).sync();        f.channel().closeFuture().sync();    } finally {        workerGroup.shutdownGracefully();        bossGroup.shutdownGracefully();    }}}

首先添加了idleStateHandler用于监听链接idle，如果连接到达idle时间，这个handler会触发idleEvent，之后通过重写userEventTriggered方法，完成idle事件的处理。

可以用telnet进行测试：

telnet 127.0.0.1 8080

测试结果：

read idle

write idle

read idle

all idle

write idle

read idle

write idle

read idle