code: public byte[] digest(File file) throws CryptoException{
  		InputStream in = null;
  		try {
  			in = FileUtil.getInputStream(file);
  			return digest(in);
  		} finally{
  			IoUtil.close(in);
  		}
  	}
docs: 生成文件摘要<br>
  使用默认缓存大小，见 {@link IoUtil#DEFAULT_BUFFER_SIZE}
  
  @param file 被摘要文件
  @return 摘要bytes
  @throws CryptoException Cause by IOException