/**
  * 从云端下载文件
  *
  * @param fileName
  * @return
  */
 @Override
 public InputStream download(String fileName) {
   if (BAIDU_BCS == null) {
     BAIDU_BCS = new BaiduBCS(new BCSCredentials(AK, SK), HOST);
   }
   GetObjectRequest request = new GetObjectRequest(BUCKET, fileName);
   BaiduBCSResponse<DownloadObject> response = BAIDU_BCS.getObject(request);
   DownloadObject downloadObject = response.getResult();
   InputStream result = null;
   if (downloadObject != null) {
     result = downloadObject.getContent();
   }
   return result;
 }
 private static void getObjectWithDestFile(BaiduBCS baiduBCS, String object, File destFile) {
   GetObjectRequest getObjectRequest =
       new GetObjectRequest(AppAutoConstants.Baidu_BCS.bucket, object);
   baiduBCS.getObject(getObjectRequest, destFile);
 }