Netty中的Idle事件

转：http://blog.csdn.net/guanxinquan/article/details/10990337

 

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。