FileProvider.GetUriForFile（）在Xamarin Android中出现RuntimeException

Question

我要从Xamarin Android中的Camera拍照。

这是我在Xamarin所做的事情。

1. 启动相机活动

   private void CallTakePictureIntent ()
   {
       Intent takePictureIntent = new Intent (MediaStore.ActionImageCapture);
       // Ensure that there's a camera activity to handle the intent
       if (takePictureIntent.ResolveActivity (PackageManager) != null) {
           // Create the File where the photo should go
           Java.IO.File photoFile = null;
           try {
               photoFile = ImageHelper.CreateImageFile (this);
           } catch (Exception ex) {
               System.Console.WriteLine (ex.ToString ());
           }
           // Continue only if the File was successfully created
           if (photoFile != null) {
               sURI photoURI = FileProvider.GetUriForFile (this, UIHelper.FileProvider, photoFile);
               requestedAvatarUri = photoURI;
               takePictureIntent.PutExtra (MediaStore.ExtraOutput, photoURI);
               StartActivityForResult (takePictureIntent, REQUEST_TAKE_PICTURE);
           }
       }
   }
   

2. 创建临时文件。

   public static Java.IO.File CreateImageFile (Context context)
   {
       // Create an image file name
       string timeStamp = DateTime.Now.ToString ("yyyyMMdd_HHmmss");
       string imageFileName = "JPEG_" + timeStamp + "_";
       Java.IO.File storageDir = context.GetExternalFilesDir (Android.OS.Environment.DirectoryPictures);
       Java.IO.File image = Java.IO.File.CreateTempFile (
               imageFileName,  /* p                refix */
               ".jpg",         /* suffix */
               storageDir      /* directory */
       );
       return image;
   }
   

3. Android.Manifest

       <provider
       android:name="android.support.v4.content.FileProvider"
       android:authorities="com.masterbee.xamapp-dev.fileprovider"
       android:exported="false"
       android:grantUriPermissions="true">
       <meta-data
           android:name="android.support.FILE_PROVIDER_PATHS"
           android:resource="@xml/file_paths" />
   </provider>     
   

4. XML / file_paths.xml

   <external-path name="external_images" path="Pictures/" />
   

我认为我已经正确完成了所有工作，除了FileProvider.GetUriForFile（）行中的运行时异常。

这里的通话追踪。 enter image description here