HarmonyOS cameraPicker设置自定义存储路径无效

代码如下，尝试使用缓存路径替换pickerProfile.saveUri = filePath，但是执行code返回-1，执行失败。如何设置才能指定自定义缓存路径？

async takePhoto() {
  try {
    // Configure to launch the rear camera
    let pickerProfile: cameraPicker.PickerProfile = { cameraPosition: this.cameraPosition[1] };
    let filePath = getContext(this).cacheDir + '/' + UUIDUtil.get16UUID() + '.jpeg'
    let resultFile = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
    pickerProfile.saveUri = filePath
    let pickerResult: cameraPicker.PickerResult = await cameraPicker.pick(getContext(this),
      [this.mediaType[0]], pickerProfile);
    if (pickerResult.resultCode != 0 || !pickerResult.resultUri.length) {
      return
    }
    this.addPhotoFromUri(pickerResult.resultUri)
  } catch (error) {
  }
}
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