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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.objectecho;
  
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandlerAdapter;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static io.netty.channel.ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE;
  
  /**
   * Handler implementation for the object echo client.  It initiates the
   * ping-pong traffic between the object echo client and server by sending the
   * first message to the server.
   */
  public class ObjectEchoClientHandler extends ChannelInboundHandlerAdapter {
  
      private final List<Integer> firstMessage;
  
      /**
       * Creates a client-side handler.
       */
      public ObjectEchoClientHandler() {
          firstMessage = new ArrayList<Integer>(ObjectEchoClient.SIZE);
          for (int i = 0; i < ObjectEchoClient.SIZE; i ++) {
              firstMessage.add(Integer.valueOf(i));
          }
      }
  
      @Override
      public void channelActive(ChannelHandlerContext ctx) {
          // Send the first message if this handler is a client-side handler.
          ChannelFuture future = ctx.writeAndFlush(firstMessage);
          future.addListener(FIRE_EXCEPTION_ON_FAILURE); // Let object serialisation exceptions propagate.
      }
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) {
          // Echo back the received object to the server.
          ctx.write(msg);
      }
  
      @Override
      public void channelReadComplete(ChannelHandlerContext ctx) {
          ctx.flush();
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          cause.printStackTrace();
          ctx.close();
      }
  }