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Flutter 启动后继续异步任务,即使用户在flatter中导航到另一个屏幕_Flutter_Dart_Async Await - Fatal编程技术网

Flutter 启动后继续异步任务,即使用户在flatter中导航到另一个屏幕

Flutter 启动后继续异步任务,即使用户在flatter中导航到另一个屏幕,flutter,dart,async-await,Flutter,Dart,Async Await,我想在后台继续异步任务,一旦从一个屏幕开始,不管用户是否导航到另一个屏幕 从图像列表屏幕用户可以选择多个图像和图像上传将开始。上传图片的功能如下 dynamic _onUploadAllAssets(String albumId, AlbumManager albumManager, List<Asset> imageList, context, albumBloc) async { for (int i = 0; i < imageList.length;

我想在后台继续异步任务,一旦从一个屏幕开始,不管用户是否导航到另一个屏幕

从图像列表屏幕用户可以选择多个图像和图像上传将开始。上传图片的功能如下

dynamic _onUploadAllAssets(String albumId, AlbumManager albumManager,
      List<Asset> imageList, context, albumBloc) async {
    for (int i = 0; i < imageList.length; i++) {
      await uploadAsset(
          imageList.first, albumId, albumManager, 0, context, albumBloc);
      albumBloc.fetchAllImages(albumId);
      imageList.remove(imageList.first);
      albumBloc.getSelectedImage(imageList);
    }
  }

dynamic uploadAsset(Asset asset, String albumId, AlbumManager albumManager,
      int index, context, albumBloc) async {
    final String uuid = Uuid().v1();
    final height = MediaQuery.of(context).size.height / 2;

    final width = asset.originalWidth * height / asset.originalHeight;

    final imageByte = await asset.getByteData(quality: 100);

    final base64Image = base64Encode(imageByte.buffer.asUint8List());
    await uploadAlbumImage(albumId, base64Image, uuid, false, index, albumBloc);
    final compressedImageBytes = await asset.getThumbByteData(
      width.round(),
      height.round(),
    );
    final compressedImageU8 = compressedImageBytes.buffer.asUint8List();
    final compressedBase64 = base64Encode(compressedImageU8);
    await uploadAlbumImage(
        albumId, compressedBase64, uuid, true, index, albumBloc);
  }

Future<bool> uploadAlbumImage(String albumId, String base64Image, String uuid,
      bool isThumbnail, int index, albumBloc) async {
    await albumManager.connectFirebase();
    final Directory systemTempDir = Directory.systemTemp;

    if (albumManager.circleAlbumCacheDir == null) {
      await albumManager.getCacheDirectory(albumId);
    }

    final encryptor = encryption.StringEncryption();
    final encryptedImage = await encryptor.getEncryption(base64Image);

    final String prefix = isThumbnail ? 'thumbnail_' : 'img_';

    final File file = File('${systemTempDir.path}/tmp$prefix$uuid.txt');
    if (file.existsSync()) {
      await file.delete();
    }
    await file.create();

    await file.writeAsString(encryptedImage);

    final StorageReference preRef =
        albumManager.storageReference.child(albumId);

    final StorageReference thumbnailRef =
        preRef.child('thumbnail').child('thumbnail_$uuid.txt');

    final StorageReference imageRef =
        preRef.child('images').child('img_$uuid.txt');

    final StorageReference ref = isThumbnail ? thumbnailRef : imageRef;

    final StorageUploadTask task = ref.putFile(
      file,
      StorageMetadata(
        contentLanguage: 'en',
        customMetadata: <String, String>{'activity': 'uploadEventImage'},
      ),
    );
    task.events.listen((storageTaskEvent) {
      final _progess = storageTaskEvent.snapshot.bytesTransferred.toDouble() /
          storageTaskEvent.snapshot.totalByteCount.toDouble();
      albumBloc.syncFileUploading(uuid, isThumbnail, _progess, index);
    });
    await task.onComplete;

    if (!task.isSuccessful) {
      ref.delete();
      await file.delete();
    } else if (isThumbnail) {
      final String thumbnailUrl = await thumbnailRef.getDownloadURL();
      final String imageUrl = await imageRef.getDownloadURL();
      await albumManager.addImageToFolder(
          albumId, uuid, thumbnailUrl, imageUrl, true);
      await albumManager.getCacheDirectory(albumId);
      albumManager.cacheImage(
          base64Image, '${albumManager.circleAlbumCacheDir}/thumb_$uuid.png');
    } else {
      await albumManager.getCacheDirectory(albumId);
      albumManager.cacheImage(
          base64Image, '${albumManager.circleAlbumCacheDir}/img_$uuid.png');
    }

    await file.delete();
    return task.isSuccessful;
  }
dynamic\u onUploadAllAssets(字符串albumId、AlbumManager、AlbumManager、,
列表imageList、context、albumBloc)异步{
对于(int i=0;i
问题是一旦图像上传开始,用户导航到另一个屏幕,则正在上传的图像将完成,但不会上载剩余的图像


当用户导航到另一个屏幕或返回到上一个屏幕时,For循环停止执行。我想继续执行for循环,直到上传所有图像。

在另一个异步函数中嵌入onUploadAllAssets应该可以完成任务否?(不使用wait关键字…

在另一个异步函数中嵌入onUploadAllAssets应该执行此任务否?(不使用wait关键字…

如果您想在后台运行,而不向用户显示任何进度线索,则必须使用“隔离”。但是,如果您想向用户显示任务的进度,则创建一个包含进度条的小部件作为小部件,并在每个页面中将其作为子小部件使用。

如果您想在后台运行,而不向用户显示任何进度线索,则必须使用“隔离”。但是,如果您想向用户显示任务的进度,那么创建一个包含progressBar的小部件作为小部件,并在每个页面中将其作为子小部件使用