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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.echo;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.buffer.ChannelBuffers;
  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.util.concurrent.atomic.AtomicLong;
  
  /**
   * Handler implementation for the echo client.  It initiates the ping-pong
   * traffic between the echo client and server by sending the first message to
   * the server.
   */
  public class EchoClientHandler extends SimpleChannelUpstreamHandler {
  
      private final ChannelBuffer firstMessage;
      private final AtomicLong transferredBytes = new AtomicLong();
  
      /**
       * Creates a client-side handler.
       */
      public EchoClientHandler() {
          firstMessage = ChannelBuffers.buffer(EchoClient.SIZE);
          for (int i = 0; i < firstMessage.capacity(); i ++) {
              firstMessage.writeByte((byte) i);
          }
      }
  
      public long getTransferredBytes() {
          return transferredBytes.get();
      }
  
      @Override
      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
          // Send the first message.  Server will not send anything here
          // because the firstMessage's capacity is 0.
          e.getChannel().write(firstMessage);
      }
  
      @Override
      public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
          // Send back the received message to the remote peer.
          transferredBytes.addAndGet(((ChannelBuffer) e.getMessage()).readableBytes());
          e.getChannel().write(e.getMessage());
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
          // Close the connection when an exception is raised.
          e.getCause().printStackTrace();
          e.getChannel().close();
      }
  }