code: public static FileInputStream getFileInputStream(String filePath) throws Exception {
          FileInputStream localFileInputStream = new FileInputStream(filePath);
          return localFileInputStream;
      }
docs: 打开对应的文件，并返回文件输入流
  
  @param filePath 文件路径
  @return 文件输入流
  @throws FileNotFoundException 如果文件不存在，则抛出异常