java/src/main/com/google/appengine/api/conversion/AssetProtoConverter.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.conversion;
   4
   5 import com.google.appengine.api.conversion.ConversionServicePb.AssetInfo;
   6 import com.google.common.base.Converter;
   7 import com.google.common.base.Preconditions;
   8 import com.google.common.base.StringUtil;
   9 import com.google.protobuf.ByteString;
  10
  11 /**
  12  * A reversible converter between {@link Asset} and its corresponding protocol
  13  * buffer.
  14  *
  15  */
  16 class AssetProtoConverter extends Converter<Asset, AssetInfo> {
  17
  18   /**
  19    * Converts an {@link Asset} to its corresponding protocol buffer.
  20    *
  21    * @throws IllegalArgumentException if the asset mime type is null, empty or
  22    *         comprises only whitespace characters
  23    */
  24   @Override
  25   public AssetInfo doForward(Asset asset) {
  26     Preconditions.checkArgument(!StringUtil.isEmptyOrWhitespace(asset.getMimeType()),
  27         "Asset mime type should not be null, empty or comprises only whitespaces");
  28
  29     return AssetInfo.newBuilder()
  30         .setMimeType(asset.getMimeType())
  31         .setData(ByteString.copyFrom(asset.getData()))
  32         .setName(asset.getName())
  33         .build();
  34   }
  35
  36   @Override
  37   public Asset doBackward(AssetInfo assetPb) {
  38     return new Asset(assetPb.getMimeType(), assetPb.getData().toByteArray(), assetPb.getName());
  39   }
  40 }