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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:
    *
    *   https://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 io.netty.example.telnet;
  
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandler.Sharable;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  
  import java.net.InetAddress;
  import java.util.Date;
  
  /**
   * Handles a server-side channel.
   */
  @Sharable
  public class TelnetServerHandler extends SimpleChannelInboundHandler<String> {
  
      @Override
      public void channelActive(ChannelHandlerContext ctx) throws Exception {
          // Send greeting for a new connection.
          ctx.write("Welcome to " + InetAddress.getLocalHost().getHostName() + "!\r\n");
          ctx.write("It is " + new Date() + " now.\r\n");
          ctx.flush();
      }
  
      @Override
      public void channelRead0(ChannelHandlerContext ctx, String request) throws Exception {
          // Generate and write a response.
          String response;
          boolean close = false;
          if (request.isEmpty()) {
              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 = ctx.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 channelReadComplete(ChannelHandlerContext ctx) {
          ctx.flush();
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          cause.printStackTrace();
          ctx.close();
      }
  }