HarmonyOS 鸿蒙Next openharmony怎么把下载的文件放到公共目录中？

可以使用这个文档 保存用户文件，可以通过文件选择器（FilePicker）将文件保存到公共目录。

function savePublicFile(context: Context, fileName: string, fileData: ArrayBuffer | string){
  let saveOptions = new filePicker.DocumentSaveOptions();
  saveOptions.newFileNames = [fileName];
  let documentViewPicker = new filePicker.DocumentViewPicker(context);
  documentViewPicker.save(saveOptions).then((saveResult) => {
    if(saveResult && saveResult.length){
      const uri = saveResult[0];
      let file = fileIo.openSync(uri, fileIo.OpenMode.READ_WRITE);
      let writeLen = fileIo.writeSync(file.fd, fileData);
      fileIo.closeSync(file);
    }

  }).catch((err: BusinessError) => {
    console.error(`Invoke documentViewPicker.save failed, code is ${err.code}, message is ${err.message}`);
  })
}