Netty心跳机制

小灰灰 2021-12-14 21:17 344阅读 0赞

## netty心跳 ##

**netty3实现心跳检测**

handleUpstream内部实现了IdleStateHandler
    #第一步在管道中添加心跳检测 Handler
    ChannelPipeline pipeline = Channels.pipeline();
    #1.定时器 2.读超时 3.写超时 4.读写超时
    pipeline.addLast("idle", new IdleStateHandler(hashedWheelTimer, 5, 5, 10));

**消息处理类**

public class HelloHandler extends SimpleChannelHandler {
       @Override
       public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
          System.out.println(e.getMessage());
       }
    
      //IdleState.  使其超时类型
       @Override
       public void handleUpstream(final ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
          if (e instanceof IdleStateEvent) {
             if(((IdleStateEvent)e).getState() == IdleState.ALL_IDLE){
                System.out.println("提玩家下线");
                //关闭会话,踢玩家下线
                ChannelFuture write = ctx.getChannel().write("time out, you will close");
                write.addListener(new ChannelFutureListener() {               
                   @Override
                   public void operationComplete(ChannelFuture future) throws Exception {
                       ctx.getChannel().close();
                   }
                });
             }
          } else {
             super.handleUpstream(ctx, e);
          }
       }

**Netty5 实现心跳检测**

*  userEventTriggered内部实现了IdleStateHandler
 *  心跳对于服务端用于清除闲置回话，对于客户端检测是否要进行重连、检测网络延迟

#第一步在管道中添加心跳检测 Handler
    ChannelPipeline pipeline = Channels.pipeline();
    #1.定时器 2.读超时 3.写超时 4.读写超时
     pipeline.addLast("idle", new IdleStateHandler(hashedWheelTimer, 5, 5, 10));

**消息处理类**

public class ServerHandler extends SimpleChannelInboundHandler<String> {
    
       @Override
       protected void messageReceived(ChannelHandlerContext ctx, String msg) throws Exception {
      System.out.println(msg); 
      ctx.channel().writeAndFlush("hi");
      ctx.writeAndFlush("hi");
       }
       
       @Override
       public void userEventTriggered(final ChannelHandlerContext ctx, Object evt) throws Exception {
          if(evt instanceof IdleStateEvent){
             IdleStateEvent event = (IdleStateEvent)evt;
             if(event.state() == IdleState.ALL_IDLE){
                //清除超时会话
                ChannelFuture writeAndFlush = ctx.writeAndFlush("you will close");
                writeAndFlush.addListener(new ChannelFutureListener() {          
                   @Override
                   public void operationComplete(ChannelFuture future) throws Exception {
                      ctx.channel().close();
                   }
                });
             }
          }else{
             super.userEventTriggered(ctx, evt);
          }
       }
       /**
        * 新客户端接入
        */
       @Override
       public void channelActive(ChannelHandlerContext ctx) throws Exception {
          System.out.println("channelActive");
       }
       /**
        * 客户端断开
        */
       @Override
       public void channelInactive(ChannelHandlerContext ctx) throws Exception {
          System.out.println("channelInactive");
       }
       /**
        * 异常
        */
       @Override
       public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
          cause.printStackTrace();
       }  
    }

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