Telnet - 访问8080端口并发送数据

telnet localhost 8080

package com.netty.discard;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
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;
/**
* 丢弃任何进入的数据
*/
public class DiscardServer {
  private int port;
  public DiscardServer(int port) {
    this.port = port;
  }
  public void run() throws Exception {
    EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    ServerBootstrap b = new ServerBootstrap(); // (2)
    try {
      b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class); // (3)
      b.childHandler(new ChannelInitializer<SocketChannel>(){ // (4)
        @Override
        public void initChannel(SocketChannel ch) throws Exception {
          ch.pipeline().addLast(new DiscardServerHandler());
        }
      }).option(ChannelOption.SO_BACKLOG, 128).childOption(ChannelOption.SO_KEEPALIVE, true); // (6)
      // 绑定端口，开始接收进来的连接
      ChannelFuture f = b.bind(port).sync(); // (7)
      // 等待服务器 socket 关闭 。
      // 在这个例子中，这不会发生，但你可以优雅地关闭你的服务器。
      f.channel().closeFuture().sync();
    } finally {
      workerGroup.shutdownGracefully();
      bossGroup.shutdownGracefully();
    }
  }
  public static void main(String[] args) throws Exception {
    int port;
    if (args.length > 0) {
      port = Integer.parseInt(args[0]);
    } else {
      port = 8080;
    }
    new DiscardServer(port).run();
  }
}

package com.netty.discard;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.ReferenceCountUtil;
/**
* 处理服务端 channel.
*/
public class DiscardServerHandler extends ChannelInboundHandlerAdapter { 
  @Override
  public void channelRead(ChannelHandlerContext ctx, Object msg) { // (2)
    // 默默地丢弃收到的数据
//    ((ByteBuf) msg).release(); // (3)
    ByteBuf in = (ByteBuf) msg;
    try {
      while(in.isReadable()){
        System.out.print((char)in.readByte());
        System.out.flush();
      }
    }finally{
      ReferenceCountUtil.release(msg); // (2)
    } 
  }
  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // (4)
    // 当出现异常就关闭连接
    cause.printStackTrace();
    ctx.close();
  }
}