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   /*
    * Copyright 2016 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.redis;
  
  import io.netty.buffer.ByteBufUtil;
  import io.netty.channel.ChannelDuplexHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.CodecException;
  import io.netty.handler.codec.redis.ArrayRedisMessage;
  import io.netty.handler.codec.redis.ErrorRedisMessage;
  import io.netty.handler.codec.redis.FullBulkStringRedisMessage;
  import io.netty.handler.codec.redis.IntegerRedisMessage;
  import io.netty.handler.codec.redis.RedisMessage;
  import io.netty.handler.codec.redis.SimpleStringRedisMessage;
  import io.netty.util.CharsetUtil;
  import io.netty.util.ReferenceCountUtil;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * An example Redis client handler. This handler read input from STDIN and write output to STDOUT.
   */
  public class RedisClientHandler extends ChannelDuplexHandler {
  
      @Override
      public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
          String[] commands = ((String) msg).split("\\s+");
          List<RedisMessage> children = new ArrayList<RedisMessage>(commands.length);
          for (String cmdString : commands) {
              children.add(new FullBulkStringRedisMessage(ByteBufUtil.writeUtf8(ctx.alloc(), cmdString)));
          }
          RedisMessage request = new ArrayRedisMessage(children);
          ctx.write(request, promise);
      }
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) {
          RedisMessage redisMessage = (RedisMessage) msg;
          printAggregatedRedisResponse(redisMessage);
          ReferenceCountUtil.release(redisMessage);
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          System.err.print("exceptionCaught: ");
          cause.printStackTrace(System.err);
          ctx.close();
      }
  
      private static void printAggregatedRedisResponse(RedisMessage msg) {
          if (msg instanceof SimpleStringRedisMessage) {
              System.out.println(((SimpleStringRedisMessage) msg).content());
          } else if (msg instanceof ErrorRedisMessage) {
              System.out.println(((ErrorRedisMessage) msg).content());
          } else if (msg instanceof IntegerRedisMessage) {
              System.out.println(((IntegerRedisMessage) msg).value());
          } else if (msg instanceof FullBulkStringRedisMessage) {
              System.out.println(getString((FullBulkStringRedisMessage) msg));
          } else if (msg instanceof ArrayRedisMessage) {
              for (RedisMessage child : ((ArrayRedisMessage) msg).children()) {
                  printAggregatedRedisResponse(child);
              }
          } else {
              throw new CodecException("unknown message type: " + msg);
          }
      }
  
      private static String getString(FullBulkStringRedisMessage msg) {
          if (msg.isNull()) {
              return "(null)";
          }
          return msg.content().toString(CharsetUtil.UTF_8);
      }
  }