.NET MAUI中Android 14下Permissions.RequestAsync()无法正常工作

我正在开发一个.NET MAUI应用，在Android 14中请求权限时遇到问题。使用Permissions.RequestAsync()时，权限对话框无法弹出，但在Android 12模拟器和Android 11真机上均能正常工作。奇怪的是，该权限甚至未在设备设置中显示。

现有代码 #

权限检查与请求代码

public static async Task<bool> HasStoragePermission()
{
    PermissionStatus status = await Permissions.CheckStatusAsync<Permissions.StorageWrite>();
    PermissionStatus status2 = await Permissions.CheckStatusAsync<Permissions.StorageRead>();

    return status == PermissionStatus.Granted && status2 == PermissionStatus.Granted;
}

public static async Task<bool> RequestPermissionStorage()
{            
    var status2 = await Permissions.RequestAsync<Permissions.StorageRead>();
    var status = await Permissions.RequestAsync<Permissions.StorageWrite>();            
    return HasStoragePermission().Result;
}

Android清单文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true" android:usesCleartextTraffic="true">    
  </application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
</manifest>

问题原因 #

Android 13（API 33）及以上版本彻底重构了存储权限体系，原有的READ_EXTERNAL_STORAGE和WRITE_EXTERNAL_STORAGE权限被废弃，替换为细分的媒体权限；Android 14进一步收紧权限规则，旧权限声明会被系统直接忽略，导致权限对话框不弹出且设置中无对应选项。

解决方案 #

1. 更新Android清单权限

根据业务需求替换为对应权限：

• 仅访问图片/视频/音频时，添加细分媒体权限：

<uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
<uses-permission android:name="android.permission.READ_MEDIA_VIDEO" />
<uses-permission android:name="android.permission.READ_MEDIA_AUDIO" />

• 需要访问所有文件（含非媒体文件）时，添加特殊权限（注意该权限需引导用户手动开启）：

<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
    android:minSdkVersion="30" />

2. 修改权限请求代码

对应替换.NET MAUI的权限类型：

• 媒体文件权限适配代码：

public static async Task<bool> HasMediaPermission()
{
    var imagesStatus = await Permissions.CheckStatusAsync<Permissions.Media.Images>();
    var videoStatus = await Permissions.CheckStatusAsync<Permissions.Media.Video>();
    var audioStatus = await Permissions.CheckStatusAsync<Permissions.Media.Audio>();

    return imagesStatus == PermissionStatus.Granted && 
           videoStatus == PermissionStatus.Granted && 
           audioStatus == PermissionStatus.Granted;
}

public static async Task<bool> RequestMediaPermission()
{            
    var imagesStatus = await Permissions.RequestAsync<Permissions.Media.Images>();
    var videoStatus = await Permissions.RequestAsync<Permissions.Media.Video>();
    var audioStatus = await Permissions.RequestAsync<Permissions.Media.Audio>();            
    return await HasMediaPermission();
}

• 全文件访问权限适配代码：

public static async Task<bool> HasFullStoragePermission()
{
    var status = await Permissions.CheckStatusAsync<Permissions.StorageManage>();
    return status == PermissionStatus.Granted;
}

public static async Task<bool> RequestFullStoragePermission()
{            
    var status = await Permissions.RequestAsync<Permissions.StorageManage>();
    // 权限被拒绝时，引导用户跳转到设置页开启
    if (status == PermissionStatus.Denied && DeviceInfo.Version.Major >= 11)
    {
        AppInfo.ShowSettingsUI();
    }
    return await HasFullStoragePermission();
}

3. 修复异步代码死锁问题

原代码中return HasStoragePermission().Result;会触发异步死锁，需改为await HasStoragePermission();。

内容的提问来源于stack exchange，提问作者Thiago Schmitz