Xamarin 表单：相机和图库在 android 中不工作，显示权限异常

Question

在我的项目中加载相机和画廊时出现以下异常。

相机

Exception:>Plugin.Media.Abstractions.MediaPermissionException: Camera permission(s) are required. at Plugin.Media.MediaImplementation+d__17.MoveNext () [0x0009

图库

Does not have storage permission granted, requesting.01-02 15:16:08.566 I/mono-stdout(12958): Does not have storage permission granted, requesting. Storage permission Denied. 01-02 15:16:08.567 I/mono-stdout(12958): Storage permission Denied.[0:] Exception:>Plugin.Media.Abstractions.MediaPermissionException: Storage permission(s) are required. at Plugin.Media.MediaImplementation+d__16.MoveNext () [0x00091] in <5939e997f291496f805023da28f3a447>:0 --- End of stack trace from previous location where exception was thrown ---

我已经在清单文件中添加了所有权限。

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在主活动中添加了以下代码：

[assembly: UsesFeature("android.hardware.camera", Required = false)]
[assembly: UsesFeature("android.hardware.camera.autofocus", Required = false)]

public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
 {
     PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);
 }

清单文件中的提供商详细信息：

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

file_paths.xml

<?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>

相机和图库代码：

 public async void OpenMygallery()
    {
        try
        {
            await CrossMedia.Current.Initialize();

            if (!CrossMedia.Current.IsPickPhotoSupported)
            {
                ShowAlert("No photos available.");
                return;
            }

            _mediaFile = await CrossMedia.Current.PickPhotoAsync();

            if (_mediaFile == null)
                return;

            tweetPicture.Source = ImageSource.FromStream(() =>
            {
                return _mediaFile.GetStream();
            });
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine("Exception:>" + ex);
        }
    }

public async void OpenMyCamera()
    {
        try
        {
            await CrossMedia.Current.Initialize();

            if (!CrossMedia.Current.IsCameraAvailable || !CrossMedia.Current.IsTakePhotoSupported)
            {
                ShowAlert("No camera available.");
                return;
            }

            _mediaFile = await CrossMedia.Current.TakePhotoAsync(new Plugin.Media.Abstractions.StoreCameraMediaOptions
            {
                Directory = "Sample",
                Name = "test.jpg",
                AllowCropping = true
            });

            if (_mediaFile == null)
                return;

            tweetPicture.Source = ImageSource.FromStream(() =>
            {
                return _mediaFile.GetStreamWithImageRotatedForExternalStorage();
            });
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine("Exception:>" + ex);
        }
    }

错误信息：

插件版本号：4.0.1.5

测试设备：红米 Note 5 Pro

VS 版本：15.9.3

Xamarin 版本：3.4.0.1008975

任何人都可以为此提出解决方案吗？

Answer 1

在 manifest/info.plist 文件中设置权限是第一步，但用户还需要授予这些权限。

您始终可以添加权限检查以确保用户确实允许该应用访问 camera/location/photos/whatever。

查看James Montemagno's Permissions Plugin权限检查和请求。

Xamarin 表单：相机和图库在 android 中不工作，显示权限异常

Xamarin forms: Camera and gallery are not working in android, showing permission exception

media

permissions

camera

gallery

xamarin.forms