HarmonyOS ArkTS怎么读取整个文件的内容

参考示例如下：

import { BusinessError } from '@kit.BasicServicesKit';
import { fileIo as fs, ReadTextOptions } from '@kit.CoreFileKit';

let filePath = pathDir + "/test.txt";
let readTextOption: ReadTextOptions = {
  offset: 1,
  length: 0,
  encoding: 'utf-8'
};
let stat = fs.statSync(filePath);
readTextOption.length = stat.size;
fs.readText(filePath, readTextOption, (err: BusinessError, str: string) => {
  if (err) {
    console.error("readText failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("readText succeed:" + str);
  }
});

参考链接：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-file-fs-V5#fsreadtext