Xamarin Forms自动生成AndroidManifest.xml时，如何添加<provider>修复相机问题？

Hey there, let's tackle this camera problem you're facing after upgrading your Android system. I've dealt with this exact scenario before, so here's a clear, step-by-step solution to get your camera working again:

1. Create the File Provider Path Configuration File #

First, we need to define which file paths our app will share via File Provider.

• In your Xamarin Android project, navigate to the Resources folder. If there's no xml subfolder, create one.
• Inside the xml folder, add a new XML file named file_paths.xml with this content:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- Use this if your images are stored in the app's private external Pictures directory -->
    <external-files-path name="my_images" path="Pictures" />
    
    <!-- Uncomment below if you need to share from the root external storage (less secure) -->
    <!-- <external-path name="external_files" path="." /> -->
</paths>

Note: Choose the path that matches where you're saving your camera images. external-files-path is recommended because it's app-specific and doesn't require extra storage permissions.

2. Add the Provider to Your AndroidManifest.xml #

You mentioned your AndroidManifest is auto-generated, but don't worry—you can edit the editable manifest file in your project (found under the Properties folder, not the auto-generated one in the obj directory).

Open Properties/AndroidManifest.xml and add the <provider> node inside the <application> tag:

<provider
    android:name="androidx.core.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" />
</provider>

Important: If your project still uses the old Android Support Libraries (not recommended), replace androidx.core.content.FileProvider with android.support.v4.content.FileProvider. But I strongly suggest migrating to AndroidX if you haven't already—it's the modern replacement for Support Libraries.

3. Update Your Camera Intent Code #

Your current code uses Uri.FromFile() which creates a file:// URI—this is blocked on Android 7.0+. Replace it with FileProvider to generate a secure content:// URI:

// Get your app's authority (matches what you set in the manifest)
var authority = PackageName + ".fileprovider";

// Generate the content URI using FileProvider
var contentUri = FileProvider.GetUriForFile(this, authority, AppClass._file);

// Update the intent with the new URI
var intent = new Intent(MediaStore.ActionImageCapture);
intent.PutExtra(MediaStore.ExtraOutput, contentUri);

// Grant temporary permissions to the camera app to access this URI
intent.AddFlags(ActivityFlags.GrantReadUriPermission);
intent.AddFlags(ActivityFlags.GrantWriteUriPermission);

// Launch the camera
StartActivityForResult(intent, YOUR_REQUEST_CODE);

Make sure AppClass._file is saved in the same path you defined in file_paths.xml (e.g., GetExternalFilesDir(Android.OS.Environment.DirectoryPictures)).

Quick Checks to Avoid Headaches #

• Double-check that the authority value in your code matches exactly what's in the manifest (${applicationId}.fileprovider maps to your app's package name plus ".fileprovider").
• Ensure android:exported="false" is set on the provider—this is a security requirement, as FileProvider shouldn't be exported to other apps.

内容的提问来源于stack exchange，提问作者AKrist