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   /*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package org.jboss.netty.example.telnet;
  
  import org.jboss.netty.channel.ChannelEvent;
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.ChannelFutureListener;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.ChannelStateEvent;
  import org.jboss.netty.channel.ExceptionEvent;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
  
  import java.net.InetAddress;
  import java.util.Date;
  
  /**
   * Handles a server-side channel.
   */
  public class TelnetServerHandler extends SimpleChannelUpstreamHandler {
  
      @Override
      public void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
          if (e instanceof ChannelStateEvent) {
              System.err.println(e);
          }
          super.handleUpstream(ctx, e);
      }
  
      @Override
      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
          // Send greeting for a new connection.
          e.getChannel().write("Welcome to " + InetAddress.getLocalHost().getHostName() + "!\r\n");
          e.getChannel().write("It is " + new Date() + " now.\r\n");
      }
  
      @Override
      public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
  
          // Cast to a String first.
          // We know it is a String because we put some codec in TelnetPipelineFactory.
          String request = (String) e.getMessage();
  
          // Generate and write a response.
          String response;
          boolean close = false;
          if (request.length() == 0) {
              response = "Please type something.\r\n";
          } else if ("bye".equals(request.toLowerCase())) {
              response = "Have a good day!\r\n";
              close = true;
          } else {
              response = "Did you say '" + request + "'?\r\n";
          }
  
          // We do not need to write a ChannelBuffer here.
          // We know the encoder inserted at TelnetPipelineFactory will do the conversion.
          ChannelFuture future = e.getChannel().write(response);
  
          // Close the connection after sending 'Have a good day!'
          // if the client has sent 'bye'.
          if (close) {
              future.addListener(ChannelFutureListener.CLOSE);
          }
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
          e.getCause().printStackTrace();
          e.getChannel().close();
      }
  }