code: private void checkFile() throws IORuntimeException {
  		if (false == file.exists()) {
  			throw new IORuntimeException("File not exist: " + file);
  		}
  		if (false == file.isFile()) {
  			throw new IORuntimeException("Not a file:" + file);
  		}
  	}
docs: 检查文件
  
  @throws IORuntimeException IO异常