HarmonyOS 鸿蒙Next：web组件如何实现直接监听网页下载行为并下载

下载回调可以借鉴以下代码：

//这里测试的是下载文件到download目录，伙伴测试需要开下网络权限
let context = getContext(this) as common.UIAbilityContext
const documentViewPicker = new picker.DocumentViewPicker(context);

let sanPath = context.filesDir + "/" + Date.now() + ".docx";
request.downloadFile(context,
  {
    url: 'https://xxx',
    filePath: sanPath
})
.then((downloadTask: request.DownloadTask) => {
  downloadTask.on('complete', () => {
    console.info('download complete');
    const documentSaveOptions = new picker.DocumentSaveOptions();
    documentSaveOptions.pickerMode = picker.DocumentPickerMode.DOWNLOAD;

    // 创建文件管理器保存选项实例 documentSaveOptions.pickerMode = picker.DocumentPickerMode.DOWNLOAD
    // 保存文件名（可选） const documentViewPicker = new picker.DocumentViewPicker;
    documentViewPicker.save(documentSaveOptions).then(async (documentSaveResult) => {
      // 获取到到图片或者视频文件的URI后进行文件读取等操作
      let uri = documentSaveResult[0];
      //把这里的path存起来，作为后续保存文件的path
      // let path: string = new FileUri.FileUri(uri).path
      let path: string = 'file://docs/storage/Users/currentUser/Download/com.example.test'

      let filePath: string = `${path}/test.docx`;

      // 测试权限并创建
      // const testCreateFile = await fs.open(filePath, fs.OpenMode.CREATE)

      console.info('pub uri:' + uri)
      // // 沙箱路径文件
      // let sanFile = fs.openSync(sanPath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
      // let pubFile = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
      // // 将文件从沙箱路拷贝到公共路径
      // fs.copyFileSync(sanFile.fd, pubFile.fd)
    })
    .catch((err: Error) => {
      console.error(`Invoke documentPicker.select failed, message is ${err.message}`);
    })
  })
}).catch((err: BusinessError) => {
  console.error(`Invoke downloadTask failed, code is ${err.code}, 1message is ${err.message}`);
});