HarmonyOS 鸿蒙Next 如何把本地图片保存到文件管理中

saveImage() {
  //文件保存路径
  let uri = '';
  try {
    let PhotoSaveOptions = new picker.PhotoSaveOptions();
    PhotoSaveOptions.newFileNames = ['test.png']; //保存图片默认名称
    let photoPicker = new picker.PhotoViewPicker();
    //调起系统的图片保存功能
    photoPicker.save(PhotoSaveOptions).then((PhotoSaveResult) => {
      uri = PhotoSaveResult[0];
      //获取图片的base64字符串
      let imageStr = this.context.toDataURL().split(',')[1];
      //打开文件
      let file = fs.openSync(uri, fs.OpenMode.READ_WRITE);
      //base64字符串转成buffer
      const decodeBuffer = buffer.from(imageStr, 'base64').buffer;
      //写入文件
      fs.writeSync(file.fd, decodeBuffer);
      //关闭文件
      fs.closeSync(file);
    }).catch((err: Error) => {
      console.error(err + '');
    })
  } catch (e) {
    console.error(e);
  }
}