HarmonyOS fs open 向createasset创建的图片uri 写入数据流/数据块 失败，只能使用完整buffer写入成功

//Step1：网络请求下载图片 
let OutData: http.HttpResponse 
let imagePackerApi = image.createImagePacker(); 
let packOpts : image.PackingOption = { format:"image/jpeg", quality:98 }; 
//确保网络正常 
http.createHttp().request(url, 
  { 
    method:http.RequestMethod.GET, 
    connectTimeout:60000, 
    readTimeout:60000 
  }, 
  //Step2：将网络图片转换成pixelmap 
async (error: BusinessError, data: http.HttpResponse) => { 
  if (error) { 
    console.error(`http reqeust failed with. Code: ${error.code}, message: ${error.message}`); 
  } else { 
    OutData = data 
    let code: http.ResponseCode | number = OutData.responseCode 
    if (ResponseCode.ResponseCode.OK === code) { 
      let imageData: ArrayBuffer = OutData.result as ArrayBuffer; 
      let imageSource: image.ImageSource = image.createImageSource(imageData); 
      class tmp { 
        height: number = 100 
        width: number = 100 
      } 
     // Step3：使用imagePackerApi.packing 获取数据流data 
      imageSource.createPixelMap(options).then((pixelMap: PixelMap) => { 
        this.downloadpixelMap = pixelMap 
        this.downloadpixelMap.getImageInfo().then((info: image.ImageInfo) => { 
          console.info('info.width = ' +　info.size.width) 
        }).catch((err: BusinessError) =>{ 
          console.error("Faild " + err); 
        }) 
        imagePackerApi.packing(pixelMap, packOpts).then(async (buffer : ArrayBuffer) => { 
         // Step4：获取getPhotoAccessHelper 写入文件将图片保存到相册 
          const context = getContext(this) 
          let helper = photoAccessHelper.getPhotoAccessHelper(context) 
          let uri = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, 'png') 
          let file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE) 
          //let buffer = new ArrayBuffer(this.pixelMap!.getPixelBytesNumber()) 
          // await this.image!.readPixelsToBuffer(buffer) 
          // 写入文件 
          // 写入文件 注意加一个packing的过程 
          await fs.write(file.fd, buffer); 
          // 关闭文件 
          await fs.close(file.fd); 
          console.log("44444444454") 
          this.message = "保存成功"