路径提供程序颤振下载文件答案

【问题标题】：path provider flutter download file路径提供程序颤振下载文件
【发布时间】：2022-01-05 09:03:35
【问题描述】：

我想在我的应用程序中下载文件，我使用了Dio、path_provider、permission_handler 所以我应该在 android 的 android 清单和 ios 的信息中写一些东西。

我做到了。但它不起作用，当我单击下载按钮时出现此错误：

I/flutter (11919): Directory: '/storage/emulated/0/Android/data/com.example.podkadeh/files'
I/flutter (11919): FileSystemException: Cannot open file, path = '/storage/emulated/0/podkadeh/Image/image.jpg' (OS Error: Permission denied, errno = 13)
I/flutter (11919): Problem Downloading File

这个OS Error: Permission denied, errno = 13

我在清单中写了这行：

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_MEDIA_LOCATION"/>
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
    tools:ignore="ScopedStorage"/>
<uses-permission android:name="android.permission"

并在应用程序中写了这个：

android:requestLegacyExternalStorage="true"

但还是不行，我不能下载它

这是我的下载文件代码：

class DownloadImage extends StatefulWidget {
  const DownloadImage (
      {Key? key,})
      : super(key: key);    
  @override
  _DownloadImage State createState() => _DownloadImage State();
}
class _DownloadImageState extends State<DownloadImage > {

 Future<bool> saveImageUrl(String url, String fileName) async {
    Directory? directory;
    try {
      if (Platform.isAndroid) {
        if (await _requestPermission(Permission.storage)) {
          directory = await getExternalStorageDirectory();
          String newPath = "";
          print(directory);
          List<String> paths = directory!.path.split("/");
          for (int x = 1; x < paths.length; x++) {
            String folder = paths[x];
            if (folder != "Android") {
              newPath += "/" + folder;
            } else {
              break;
            }
          }
          newPath = newPath + "/podkadeh" + "/Image";
          directory = Directory(newPath);
        } else {
          return false;
        }
      } else {
        if (await _requestPermission(Permission.photos)) {
          directory = await getTemporaryDirectory();
        } else {
          return false;
        }
      }
      File saveFile = File(directory.path + "/$fileName");
      if (!await directory.exists()) {
        await directory.create(recursive: true);
      }
      if (await directory.exists()) {
        await dio.download(url, saveFile.path,
            onReceiveProgress: (value1, value2) {
              setState(() {
                progress = value1 / value2;
              });
            });
        if (Platform.isIOS) {
          await ImageGallerySaver.saveFile(saveFile.path,
              isReturnPathOfIOS: true);
        }
        return true;
      }
      return false;
    } catch (e) {
      print(e);
      return false;
    }
  }

  Future<bool> _requestPermission(Permission permission) async {

    if (await permission.isGranted) {
      return true;
    } else {
      var result = await permission.request();
      if (result == PermissionStatus.granted) {
        return true;
      }
    }
    return false;
  }

  downloadFile() async {
    setState(() {
      loading = true;
      progress = 0;
    });

    bool downloadedImage =  await saveImageUrl(
        "https://test.podkadeh.ir/image-cache/Ep-61c9c0152ab37f246dd35a65-500.jpg",
        "image.jpg");

    if (downloadedImage) {
      print("File Downloaded");
    } else {
      print("Problem Downloading File");
    }
    setState(() {
      loading = false;
    });
  }



  @override
  Widget build(BuildContext context) {
    return (progress != 0 && progress != 100)
        ? CircularProgressIndicator(
            backgroundColor: loading ? Colors.amber : Colors.black,
            valueColor:
                AlwaysStoppedAnimation(loading ? Colors.blue : Colors.pink),
            strokeWidth: progress,
            value: progress,
          )
        : IconButton(

            icon: SvgPicture.asset(MyIcons.frame, color: MyColors.black,height: 20,width: 20,),
            onPressed: downloadFile,
            padding: const EdgeInsets.all(10),
          );
  }
}

顺便说一句，我使用 compileSdkVersion 31 并在 gradle.properties 中使用它：

android.useAndroidX=true
android.enableJetifier=true

【问题讨论】：

标签： android flutter dart android-manifest dio

【解决方案1】：

我通过以下解决方案解决了这个问题：而不是仅仅要求Permission.storage ，我还添加了两个权限请求Permission.accessMediaLocation , Permission.manageExternalStorage，以支持所有版本的Android。

try {
  if (Platform.isAndroid) {
    if (await _requestPermission(Permission.storage) &&
      await _requestPermission(Permission.accessMediaLocation) &&
      await _requestPermission(Permission.manageExternalStorage)) {
         directory = await getExternalStorageDirectory();
         String newPath = "";
         print(directory);
         .......

结果是：

Performing hot restart...
Syncing files to device Android SDK built for x86...
Restarted application in 2,177ms.
I/flutter ( 3712): Directory: '/storage/emulated/0/Android/data/com.example.untitled/files'
I/flutter ( 3712): File Downloaded

【讨论】：