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   /*
    * Copyright 2014 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.memcache.binary;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  import io.netty.channel.ChannelDuplexHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.memcache.binary.BinaryMemcacheOpcodes;
  import io.netty.handler.codec.memcache.binary.BinaryMemcacheRequest;
  import io.netty.handler.codec.memcache.binary.DefaultBinaryMemcacheRequest;
  import io.netty.handler.codec.memcache.binary.DefaultFullBinaryMemcacheRequest;
  import io.netty.handler.codec.memcache.binary.FullBinaryMemcacheResponse;
  import io.netty.util.CharsetUtil;
  
  public class MemcacheClientHandler extends ChannelDuplexHandler {
  
      /**
       * Transforms basic string requests to binary memcache requests
       */
      @Override
      public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
          String command = (String) msg;
          if (command.startsWith("get ")) {
              String keyString = command.substring("get ".length());
              ByteBuf key = Unpooled.wrappedBuffer(keyString.getBytes(CharsetUtil.UTF_8));
  
              BinaryMemcacheRequest req = new DefaultBinaryMemcacheRequest(key);
              req.setOpcode(BinaryMemcacheOpcodes.GET);
  
              ctx.write(req, promise);
          } else if (command.startsWith("set ")) {
              String[] parts = command.split(" ", 3);
              if (parts.length < 3) {
                  throw new IllegalArgumentException("Malformed Command: " + command);
              }
              String keyString = parts[1];
              String value = parts[2];
  
              ByteBuf key = Unpooled.wrappedBuffer(keyString.getBytes(CharsetUtil.UTF_8));
              ByteBuf content = Unpooled.wrappedBuffer(value.getBytes(CharsetUtil.UTF_8));
              ByteBuf extras = ctx.alloc().buffer(8);
              extras.writeZero(8);
  
              BinaryMemcacheRequest req = new DefaultFullBinaryMemcacheRequest(key, extras, content);
              req.setOpcode(BinaryMemcacheOpcodes.SET);
  
              ctx.write(req, promise);
          } else {
              throw new IllegalStateException("Unknown Message: " + msg);
          }
      }
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) {
          FullBinaryMemcacheResponse res = (FullBinaryMemcacheResponse) msg;
          System.out.println(res.content().toString(CharsetUtil.UTF_8));
          res.release();
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          cause.printStackTrace();
          ctx.close();
      }
  }