HarmonyOS鸿蒙Next中图片以文件形式上传后台拿不到值

可以参考以下demo

import axios from '@ohos/axios'
import { FormData } from '@ohos/axios'

let formData = new FormData()

formData.append('file', 'internal://cache/blue.jpg')

// formData.append('file', cacheDir + '/hello.txt'); uri支持传入沙箱路径

// 发送请求
axios.post<string, AxiosResponse<string>, FormData>('https://www.xxx.com/upload', formData, {
  headers: { 'Content-Type': 'multipart/form-data' },
  context: getContext(this),
  onUploadProgress: (progressEvent: AxiosProgressEvent): void => {
    console.info(progressEvent && progressEvent.loaded && progressEvent.total ? Math.ceil(progressEvent.loaded / progressEvent.total * 100) + '%' : '0%');
  },
}).then((res: AxiosResponse<string>) => {
  console.info("result" + JSON.stringify(res.data));
}).catch((err: AxiosError) => {
  console.error("error:" + JSON.stringify(err));
})

import picker from '@ohos.file.picker';
import fs from '@ohos.file.fs';
import axios, { AxiosError, AxiosProgressEvent, AxiosResponse } from '@ohos/axios'
import { FormData } from '@ohos/axios'
import { common } from '@kit.AbilityKit';

@Entry
@Component
struct Index {
  @State message: string = 'hello World';

  context = getContext(this) as common.UIAbilityContext

  build() {
    Button('选择').onClick(() => {
      let uris: Array<string> = [];
      let documentViewPicker = new picker.PhotoViewPicker();
      documentViewPicker.select({
        MIMEType: picker.PhotoViewMIMETypes.IMAGE_TYPE,
        maxSelectNumber: 1
      }).then((photoSelectResult: picker.PhotoSelectResult) => {
        uris = photoSelectResult.photoUris;
        console.info('photoViewPicker.select to file succeed and uris are:' + uris);
        let fileSource = fs.openSync(uris[0], fs.OpenMode.READ_ONLY);
        let fileDes = fs.openSync(`${this.context.cacheDir}/1.jpg`, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
        fs.copyFileSync(fileSource.fd, fileDes.fd)
        fs.closeSync(fileSource);
        fs.closeSync(fileDes);
        let formData = new FormData()
        formData.append('file', `${this.context.cacheDir}/1.jpg`); //uri支持传入沙箱路径
        // 发送请求
      })
    })
  }
}