5、netty第四个例子，空闲检测handle

netty可支持空闲检测的处理器，用于心态检测，当服务器端超出等待时间，没发生事件时，会触发handler中的方法 userEventTriggered。

initializer

 1 import io.netty.channel.ChannelInitializer;
 2 import io.netty.channel.ChannelPipeline;
 3 import io.netty.channel.socket.SocketChannel;
 4 import io.netty.handler.timeout.IdleStateHandler;
 5 
 6 import java.util.concurrent.TimeUnit;
 7 
 8 public class MyServerInitlalizer extends ChannelInitializer<SocketChannel> {
 9     @Override
10     protected void initChannel(SocketChannel ch) throws Exception {
11         ChannelPipeline pipeline  = ch.pipeline();
12 
13         //空闲事件处理器  读空闲5s    写空闲3s   读写空闲7s  
14         pipeline.addLast(new IdleStateHandler(5,7,3,TimeUnit.SECONDS)); //空闲检测   在一定时间间隔内 没有读写
15         pipeline.addLast(new MyServerHandler());//自定义的空闲事件处理器
16 
17     }
18 }

handler

 1 import io.netty.channel.ChannelHandlerContext;
 2 import io.netty.channel.ChannelInboundHandler;
 3 import io.netty.channel.ChannelInboundHandlerAdapter;
 4 import io.netty.channel.SimpleChannelInboundHandler;
 5 import io.netty.handler.timeout.IdleStateEvent;
 6 
 7 public class MyServerHandler extends ChannelInboundHandlerAdapter {
 8     @Override
 9     public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
10         //super.userEventTriggered(ctx, evt);
11         if ( evt instanceof IdleStateEvent) {//如果是一个空闲状态
12             IdleStateEvent event = (IdleStateEvent) evt;
13 
14             String  eventType = null;
15 
16             switch (event.state()){
17                 case READER_IDLE:
18                     eventType = "读空闲";
19                     break;
20                 case WRITER_IDLE:
21                     eventType = "写空闲";
22                     break;
23                 case ALL_IDLE:
24                     eventType = "读写空闲";
25                     break;
26             }
27 
28             System.out.println(ctx.channel().remoteAddress() + "超时事件: " + eventType);
29 
30             ctx.channel().close();
31         }
32     }
33 }