/**
   * 上传文件到云端
   *
   * @param fileName
   * @param contents
   * @throws IOException
   */
  @Override
  public String upload(String fileName, byte[] contents) {
    if (BAIDU_BCS == null) {
      BAIDU_BCS = new BaiduBCS(new BCSCredentials(AK, SK), HOST);
    }
    ObjectMetadata objectMetadata = new ObjectMetadata();
    objectMetadata.setContentEncoding("utf-8");
    objectMetadata.setContentLength(contents.length);

    PutObjectRequest request =
        new PutObjectRequest(BUCKET, fileName, new ByteArrayInputStream(contents), objectMetadata);
    BAIDU_BCS.putObject(request);
    return getUrl(fileName);
  }