如何选择适合的图像和照片网络优化器下载

1、首先将下载好的文件，保存到本地目录，这个目录是用户看不到的；

2、然后通过picker的save保存文件，这个picker，它只是获取公共目录uri用的

3、当picker有回调时，将公共目录的uri获取之后，把下载好的文件复制到公共路径下，

公共路径=uris1[0]+'/'+'56151651.pdf'

  async saveSystemFile(name:string,path:string){try {let documentSaveOptions = new picker.DocumentSaveOptions();documentSaveOptions.pickerMode=picker.DocumentPickerMode.DOWNLOADdocumentSaveOptions.fileSuffixChoices = ['文档|.txt', '.pdf'];documentSaveOptions.newFileNames = [name];let documentPicker = new picker.DocumentViewPicker(getContext() as common.Context);documentPicker.save(documentSaveOptions).then((uris1: Array<string>) => {let uri = uris1[0]+'/'+name;let srcDirUriLocal: string = fileUri.getUriFromPath(path);fs.copy(srcDirUriLocal, uri, (err: BusinessError) => {if (err) {console.error(`Failed to copy: ${JSON.stringify(err)}`);return;}})}).catch((err: BusinessError) => {console.error('DocumentViewPicker.save failed with err: ' + JSON.stringify(err));});} catch (error) {let err: BusinessError = error as BusinessError;console.error('DocumentViewPicker failed with err: ' + JSON.stringify(err));}}