Xamarin FileProvider无法在Android中打开文件

Question

in my Xamarin Forms application I create pdfs that can be opened with Android application.

With device with Android 7 all works fine, now I have tested it with Android 8 and the file can't be open.

I have installed the Xam.PluginMedia and leave all default settings:

in the MainActivity I have override the OnRequestPermissionsResult function with:

Plugin.Permissions.PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);

the file_paths.xaml is:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-files-path name="my_images" path="Pictures" />
    <external-files-path name="my_movies" path="Movies" />
</paths>

and in the AndroidManifest.xml I have added:

<provider android:name="android.support.v4.content.FileProvider" 
    android:authorities="${applicationId}.fileprovider" 
    android:exported="false" 
    android:grantUriPermissions="true">
<meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/file_paths"></meta-data>

The code to open the preview is this:

public void OpenPreviewFile(string FilePath)
{

    Java.IO.File JavaFile = new Java.IO.File(FilePath);   

    Android.Net.Uri Path = FileProvider.GetUriForFile(global::Android.App.Application.Context, global::Android.App.Application.Context.PackageName + ".fileprovider", JavaFile);

    string Extension = global::Android.Webkit.MimeTypeMap.GetFileExtensionFromUrl(Path.ToString());
    string MimeType = global::Android.Webkit.MimeTypeMap.Singleton.GetMimeTypeFromExtension(Extension);
    Intent Intent = new Intent(Intent.ActionView);

    Intent.SetDataAndType(Path, MimeType);
    Intent.AddFlags(ActivityFlags.GrantReadUriPermission);
    Intent.SetFlags(ActivityFlags.ClearWhenTaskReset | ActivityFlags.NewTask);

    try
    {
        MainActivity.AppInstance.StartActivity(Intent.CreateChooser(Intent, TS.Translate("ANDROID_ScegliApp")));
    }
    catch (System.Exception)
    {
        Toast.MakeText(MainActivity.AppInstance, TS.Translate("ANDROID_ImpossibileAprireIlFIle"), ToastLength.Short).Show();
    }
}

The files generated are under this path: Android/data/MY_PACKAGE_ID/files/GeneratedReports

I have attached a video to show the actual behavior.

Video

Here a sample

Answer 1

I found the problem.

Inside the file_paths.xml , the "path" value of the nodes must be started with "/",

so with this node: <files-path name="GeneratedReports" path="/GeneratedReports" /> my code works.

Also I needed to remove MyIntent.SetFlags(ActivityFlags.ClearWhenTaskReset | ActivityFlags.NewTask);