netty4handler的执行顺序二

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我是靠谱客的博主传统万宝路，最近开发中收集的这篇文章主要介绍netty4handler的执行顺序二，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

接上一篇，上一篇是不对的处理方式，看本篇，我认为是对的

/**
* 这个用于测试handler的传递功能
* @author wangzg
*
* 本例子使用的是实现的handler中，各个函数都是先super，然后打印，除了handler1中的channelRead,这样打印出的顺序是，先2后1,也就是最后加进去的，先做，先进去的后做，跟
* 网上的不一致
*
* 本例子中各个handler中的方法，都在最后使用了super()的方法，顺序和网上的一致
*
*/
public class WangNetty44Server {

   private static final Logger LOGGER = LoggerFactory.getLogger(WangNetty44Server.class);

   public void start(int port){
       EventLoopGroup boss = new NioEventLoopGroup();
       EventLoopGroup work = new NioEventLoopGroup();
       ServerBootstrap bootstrap = new ServerBootstrap();
       try {
           bootstrap.group(boss, work)
           .channel(NioServerSocketChannel.class)
           .option(ChannelOption.SO_BACKLOG, 1024)
//           .option(ChannelOption.SO_TIMEOUT, 5 * 1000)
           .childOption(ChannelOption.SO_KEEPALIVE, true)
           .childOption(ChannelOption.SO_RCVBUF, 10 * 1024)
           .childOption(ChannelOption.SO_SNDBUF, 10 * 1024)
           .childHandler(new ChannelInitializer<SocketChannel>() {

               @Override
               protected void initChannel(SocketChannel sc) throws Exception {
                   sc.pipeline().addLast(new WangInHandler1());
                   sc.pipeline().addLast(new WangInHandler2());
                   sc.pipeline().addLast(new WangInHandler3());
               }
           });
           ChannelFuture future = bootstrap.bind(port).sync();
           future.channel().closeFuture().sync();
       } catch (Exception e) {
           LOGGER.error("server 启动失败",e);
       }finally{
           boss.shutdownGracefully();
           work.shutdownGracefully();
       }
   }

   public static void main(String[] args) {
       WangNetty44Server server = new WangNetty44Server();
       server.start(8085);
   }

}

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class WangInHandler1 extends ChannelInboundHandlerAdapter {

   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelRead");
       super.channelRead(ctx, msg);

//       ctx.fireChannelRead(msg);
   }

   @Override
   public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelReadComplete");
       super.channelReadComplete(ctx);

   }

   @Override
   public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 exceptionCaught");
       super.exceptionCaught(ctx, cause);

   }

   @Override
   public void channelActive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelActive");
       super.channelActive(ctx);

   }

   @Override
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelInactive");
       super.channelInactive(ctx);

   }

   @Override
   public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelRegistered");
       super.channelRegistered(ctx);

   }

   @Override
   public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelUnregistered");
       super.channelUnregistered(ctx);

   }

   @Override
   public void channelWritabilityChanged(ChannelHandlerContext ctx)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 channelWritabilityChanged");
       super.channelWritabilityChanged(ctx);

   }

   @Override
   public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler1 userEventTriggered");
       super.userEventTriggered(ctx, evt);

   }

}

public class WangInHandler2 extends ChannelInboundHandlerAdapter {

   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelRead");
       super.channelRead(ctx, msg);

   }

   @Override
   public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelReadComplete");
       super.channelReadComplete(ctx);

   }

   @Override
   public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 exceptionCaught");
       super.exceptionCaught(ctx, cause);

   }

   @Override
   public void channelActive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelActive");
       super.channelActive(ctx);

   }

   @Override
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelInactive");
       super.channelInactive(ctx);

   }

   @Override
   public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelRegistered");
       super.channelRegistered(ctx);

   }

   @Override
   public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelUnregistered");
       super.channelUnregistered(ctx);

   }

   @Override
   public void channelWritabilityChanged(ChannelHandlerContext ctx)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 channelWritabilityChanged");
       super.channelWritabilityChanged(ctx);

   }

   @Override
   public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler2 userEventTriggered");
       super.userEventTriggered(ctx, evt);

   }
}

public class WangInHandler3 extends ChannelInboundHandlerAdapter {

   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg)
           throws Exception {
       // TODO Auto-generated method stub
//       super.channelRead(ctx, msg);
       System.out.println(" WangInHandler3 channelRead");
   }

   @Override
   public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelReadComplete");
       super.channelReadComplete(ctx);

   }

   @Override
   public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 exceptionCaught");
       super.exceptionCaught(ctx, cause);

   }

   @Override
   public void channelActive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelActive");
       super.channelActive(ctx);

   }

   @Override
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelInactive");
       super.channelInactive(ctx);

   }

   @Override
   public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelRegistered");
       super.channelRegistered(ctx);

   }

   @Override
   public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelUnregistered");
       super.channelUnregistered(ctx);

   }

   @Override
   public void channelWritabilityChanged(ChannelHandlerContext ctx)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 channelWritabilityChanged");
       super.channelWritabilityChanged(ctx);

   }

   @Override
   public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
           throws Exception {
       // TODO Auto-generated method stub
       System.out.println(" WangInHandler3 userEventTriggered");
       super.userEventTriggered(ctx, evt);
   }
}

执行结果

WangInHandler3 channelReadComplete

下面是客户端主动停止通讯

WangInHandler1 channelReadComplete[nioEventLoopGroup-3-1] WARN io.netty.channel.DefaultChannelPipeline - An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
WangInHandler2 channelReadComplete
WangInHandler3 channelReadComplete
WangInHandler1 exceptionCaught
WangInHandler2 exceptionCaught
WangInHandler3 exceptionCaught

java.io.IOException: Connection reset by peer
   at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
   at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
   at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
   at sun.nio.ch.IOUtil.read(IOUtil.java:192)
   at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
   at io.netty.buffer.PooledUnsafeDirectByteBuf.setBytes(PooledUnsafeDirectByteBuf.java:288)
   at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1108)
   at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:345)
   at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:148)
   at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:645)
   at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580)
   at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497)
   at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459)
   at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
   at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
   at java.lang.Thread.run(Thread.java:745)
WangInHandler1 channelInactive
WangInHandler2 channelInactive
WangInHandler3 channelInactive
WangInHandler1 channelUnregistered
WangInHandler2 channelUnregistered
WangInHandler3 channelUnregistered

大家看到我把System.out和super()调换了，就执行顺序对了，都是1,2,3的执行顺序，因此每次都应该先执行自己的业务，然后super（）

需要注意的是每次向下一handler发送的时候，都需要super.channelRead(ctx, msg);它，如果handler2把他注释掉，handler3就无法channelread了，执行结果

WangInHandler1 channelRegistered
WangInHandler2 channelRegistered
WangInHandler3 channelRegistered
WangInHandler1 channelActive
WangInHandler2 channelActive
WangInHandler3 channelActive
WangInHandler1 channelRead
WangInHandler2 channelRead
WangInHandler1 channelReadComplete
WangInHandler2 channelReadComplete
WangInHandler3 channelReadComplete
WangInHandler1 channelReadComplete[nioEventLoopGroup-3-1] WARN io.netty.channel.DefaultChannelPipeline - An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
WangInHandler2 channelReadComplete
WangInHandler3 channelReadComplete
WangInHandler1 exceptionCaught
WangInHandler2 exceptionCaught
WangInHandler3 exceptionCaught

java.io.IOException: Connection reset by peer
   at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
   at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
   at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
   at sun.nio.ch.IOUtil.read(IOUtil.java:192)
   at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
   at io.netty.buffer.PooledUnsafeDirectByteBuf.setBytes(PooledUnsafeDirectByteBuf.java:288)
   at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1108)
   at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:345)
   at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:148)
   at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:645)
   at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580)
   at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497)
   at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459)
   at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
   at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
   at java.lang.Thread.run(Thread.java:745)
WangInHandler1 channelInactive
WangInHandler2 channelInactive
WangInHandler3 channelInactive
WangInHandler1 channelUnregistered
WangInHandler2 channelUnregistered