MAUI Blazor 权限经验分享 (定位,使用相机)
入门文章
Blazor Hybrid / MAUI 简介和实战
https://www.cnblogs.com/densen2014/p/16240966.html
在 Mac 上开发 .NET MAUI
https://www.cnblogs.com/densen2014/p/16057571.html
在 Windows 上开发 .NET MAUI
https://docs.microsoft.com/zh-cn/dotnet/maui/get-started/installation
之前的工程已经能正常使用blazor的webview下获取定位,使用相机等功能,新版释出后反而权限获取不到了,定位页面出现如下错误
由于这个问题主要出现在安卓系统,下面只选了安卓的步骤分享
Android
应用所需的权限和功能在 AndroidManifest.xml 中定义。请参阅 官方文档 了解 Android App Manifest。
某些 Android 设备权限需要在运行时显示提示，以便用户可以授予或拒绝该权限。 Android 有一个推荐的 workflow 用于在运行时请求权限，此工作流必须由应用手动实现。 WebView 的 WebChromeClient 负责对权限请求做出反应，因此该项目提供了一个 PermissionManagingBlazorWebChromeClient 将 Webkit 资源映射到 Android 权限并执行推荐的权限请求工作流。
在向 AndroidManifest.xml 添加其他权限后，请务必更新 PermissionManagingBlazorWebChromeClient.cs 以包含该权限的“基本原理字符串”，解释应用程序需要它的原因。可能还需要在 权限请求类型 和 Android Manifest 权限之间定义其他映射。
1. 应用所需的权限Platforms/Android/AndroidManifest.xml
以下是我所有的测试权限列表,各位看官按需自由组合.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" />
<application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true"></application>
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
<uses-feature android:name="android.hardware.location" android:required="false" />
<uses-feature android:name="android.hardware.location.gps" android:required="false" />
<uses-feature android:name="android.hardware.location.network" android:required="false" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CALL_PHONE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.ModifyAudioSettings" />
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.USE_FINGERPRINT" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.CAPTURE_AUDIO_OUTPUT" />
<uses-permission android:name="android.permission.CaptureSecureVideoOutput" />
<uses-permission android:name="android.permission.CaptureVideoOutput" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.BATTERY_STATS" />
<queries>
<intent>
<action android:name="android.media.action.IMAGE_CAPTURE" />
</intent>
</queries>
</manifest>2. 添加文件 Platforms/Android/PermissionManagingBlazorWebChromeClient.cs
using Android;
using Android.App;
using Android.Content.PM;
using Android.Graphics;
using Android.OS;
using Android.Views;
using Android.Webkit;
using AndroidX.Activity;
using AndroidX.Activity.Result;
using AndroidX.Activity.Result.Contract;
using AndroidX.Core.Content;
using Java.Interop;
using System;
using System.Collections.Generic;
using View = Android.Views.View;
using WebView = Android.Webkit.WebView;
namespace BlazorMaui;
internal class PermissionManagingBlazorWebChromeClient : WebChromeClient, IActivityResultCallback
{
// This class implements a permission requesting workflow that matches workflow recommended
// by the official Android developer documentation.
// See: https://developer.android.com/training/permissions/requesting#workflow_for_requesting_permissions
// The current implementation supports location, camera, and microphone permissions. To add your own,
// update the s_rationalesByPermission dictionary to include your rationale for requiring the permission.
// If necessary, you may need to also update s_requiredPermissionsByWebkitResource to define how a specific
// Webkit resource maps to an Android permission.
// In a real app, you would probably use more convincing rationales tailored toward what your app does.
private const string CameraAccessRationale = "This app requires access to your camera. Please grant access to your camera when requested.";
private const string LocationAccessRationale = "This app requires access to your location. Please grant access to your precise location when requested.";
private const string MicrophoneAccessRationale = "This app requires access to your microphone. Please grant access to your microphone when requested.";
private static readonly Dictionary<string, string> s_rationalesByPermission = new()
{
[Manifest.Permission.Camera] = CameraAccessRationale,
[Manifest.Permission.AccessFineLocation] = LocationAccessRationale,
[Manifest.Permission.RecordAudio] = MicrophoneAccessRationale,
// Add more rationales as you add more supported permissions.
};
private static readonly Dictionary<string, string[]> s_requiredPermissionsByWebkitResource = new()
{
[PermissionRequest.ResourceVideoCapture] = new[] { Manifest.Permission.Camera },
[PermissionRequest.ResourceAudioCapture] = new[] { Manifest.Permission.ModifyAudioSettings, Manifest.Permission.RecordAudio },
// Add more Webkit resource -> Android permission mappings as needed.
};
private readonly WebChromeClient _blazorWebChromeClient;
private readonly ComponentActivity _activity;
private readonly ActivityResultLauncher _requestPermissionLauncher;
private Action<bool>? _pendingPermissionRequestCallback;
public PermissionManagingBlazorWebChromeClient(WebChromeClient blazorWebChromeClient, ComponentActivity activity)
{
_blazorWebChromeClient = blazorWebChromeClient;
_activity = activity;
_requestPermissionLauncher = _activity.RegisterForActivityResult(new ActivityResultContracts.RequestPermission(), this);
}
public override void OnCloseWindow(Android.Webkit.WebView? window)
{
_blazorWebChromeClient.OnCloseWindow(window);
_requestPermissionLauncher.Unregister();
}
public override void OnGeolocationPermissionsShowPrompt(string? origin, GeolocationPermissions.ICallback? callback)
{
ArgumentNullException.ThrowIfNull(callback, nameof(callback));
RequestPermission(Manifest.Permission.AccessFineLocation, isGranted => callback.Invoke(origin, isGranted, false));
}
public override void OnPermissionRequest(PermissionRequest? request)
{
ArgumentNullException.ThrowIfNull(request, nameof(request));
if (request.GetResources() is not { } requestedResources)
{
request.Deny();
return;
}
RequestAllResources(requestedResources, grantedResources =>
{
if (grantedResources.Count == 0)
{
request.Deny();
}
else
{
request.Grant(grantedResources.ToArray());
}
});
}
private void RequestAllResources(Memory<string> requestedResources, Action<List<string>> callback)
{
if (requestedResources.Length == 0)
{
// No resources to request - invoke the callback with an empty list.
callback(new());
return;
}
var currentResource = requestedResources.Span[0];
var requiredPermissions = s_requiredPermissionsByWebkitResource.GetValueOrDefault(currentResource, Array.Empty<string>());
RequestAllPermissions(requiredPermissions, isGranted =>
{
// Recurse with the remaining resources. If the first resource was granted, use a modified callback
// that adds the first resource to the granted resources list.
RequestAllResources(requestedResources[1..], !isGranted ? callback : grantedResources =>
{
grantedResources.Add(currentResource);
callback(grantedResources);
});
});
}
private void RequestAllPermissions(Memory<string> requiredPermissions, Action<bool> callback)
{
if (requiredPermissions.Length == 0)
{
// No permissions left to request - success!
callback(true);
return;
}
RequestPermission(requiredPermissions.Span[0], isGranted =>
{
if (isGranted)
{
// Recurse with the remaining permissions.
RequestAllPermissions(requiredPermissions[1..], callback);
}
else
{
// The first required permission was not granted. Fail now and don't attempt to grant
// the remaining permissions.
callback(false);
}
});
}
private void RequestPermission(string permission, Action<bool> callback)
{
// This method implements the workflow described here:
// https://developer.android.com/training/permissions/requesting#workflow_for_requesting_permissions
if (ContextCompat.CheckSelfPermission(_activity, permission) == Permission.Granted)
{
callback.Invoke(true);
}
else if (_activity.ShouldShowRequestPermissionRationale(permission) && s_rationalesByPermission.TryGetValue(permission, out var rationale))
{
new AlertDialog.Builder(_activity)
.SetTitle("Enable app permissions")!
.SetMessage(rationale)!
.SetNegativeButton("No thanks", (_, _) => callback(false))!
.SetPositiveButton("Continue", (_, _) => LaunchPermissionRequestActivity(permission, callback))!
.Show();
}
else
{
LaunchPermissionRequestActivity(permission, callback);
}
}
private void LaunchPermissionRequestActivity(string permission, Action<bool> callback)
{
if (_pendingPermissionRequestCallback is not null)
{
throw new InvalidOperationException("Cannot perform multiple permission requests simultaneously.");
}
_pendingPermissionRequestCallback = callback;
_requestPermissionLauncher.Launch(permission);
}
void IActivityResultCallback.OnActivityResult(Java.Lang.Object isGranted)
{
var callback = _pendingPermissionRequestCallback;
_pendingPermissionRequestCallback = null;
callback?.Invoke((bool)isGranted);
}
#region Unremarkable overrides
// See: https://github.com/dotnet/maui/issues/6565
public override JniPeerMembers JniPeerMembers => _blazorWebChromeClient.JniPeerMembers;
public override Bitmap? DefaultVideoPoster => _blazorWebChromeClient.DefaultVideoPoster;
public override Android.Views.View? VideoLoadingProgressView => _blazorWebChromeClient.VideoLoadingProgressView;
public override void GetVisitedHistory(IValueCallback? callback)
=> _blazorWebChromeClient.GetVisitedHistory(callback);
public override bool OnConsoleMessage(ConsoleMessage? consoleMessage)
=> _blazorWebChromeClient.OnConsoleMessage(consoleMessage);
public override bool OnCreateWindow(WebView? view, bool isDialog, bool isUserGesture, Message? resultMsg)
=> _blazorWebChromeClient.OnCreateWindow(view, isDialog, isUserGesture, resultMsg);
public override void OnGeolocationPermissionsHidePrompt()
=> _blazorWebChromeClient.OnGeolocationPermissionsHidePrompt();
public override void OnHideCustomView()
=> _blazorWebChromeClient.OnHideCustomView();
public override bool OnJsAlert(WebView? view, string? url, string? message, JsResult? result)
=> _blazorWebChromeClient.OnJsAlert(view, url, message, result);
public override bool OnJsBeforeUnload(WebView? view, string? url, string? message, JsResult? result)
=> _blazorWebChromeClient.OnJsBeforeUnload(view, url, message, result);
public override bool OnJsConfirm(WebView? view, string? url, string? message, JsResult? result)
=> _blazorWebChromeClient.OnJsConfirm(view, url, message, result);
public override bool OnJsPrompt(WebView? view, string? url, string? message, string? defaultValue, JsPromptResult? result)
=> _blazorWebChromeClient.OnJsPrompt(view, url, message, defaultValue, result);
public override void OnPermissionRequestCanceled(PermissionRequest? request)
=> _blazorWebChromeClient.OnPermissionRequestCanceled(request);
public override void OnProgressChanged(WebView? view, int newProgress)
=> _blazorWebChromeClient.OnProgressChanged(view, newProgress);
public override void OnReceivedIcon(WebView? view, Bitmap? icon)
=> _blazorWebChromeClient.OnReceivedIcon(view, icon);
public override void OnReceivedTitle(WebView? view, string? title)
=> _blazorWebChromeClient.OnReceivedTitle(view, title);
public override void OnReceivedTouchIconUrl(WebView? view, string? url, bool precomposed)
=> _blazorWebChromeClient.OnReceivedTouchIconUrl(view, url, precomposed);
public override void OnRequestFocus(WebView? view)
=> _blazorWebChromeClient.OnRequestFocus(view);
public override void OnShowCustomView(View? view, ICustomViewCallback? callback)
=> _blazorWebChromeClient.OnShowCustomView(view, callback);
public override bool OnShowFileChooser(WebView? webView, IValueCallback? filePathCallback, FileChooserParams? fileChooserParams)
=> _blazorWebChromeClient.OnShowFileChooser(webView, filePathCallback, fileChooserParams);
#endregion
}3. 文件 MainPage.xaml
添加 x:Name="_blazorWebView"
<BlazorWebView x:Name="_blazorWebView" HostPage="wwwroot/index.html">
<BlazorWebView.RootComponents>
<RootComponent Selector="#app" ComponentType="{x:Type shared:App}" />
</BlazorWebView.RootComponents>
</BlazorWebView> 4. 文件 MainPage.xaml.cs
添加
_blazorWebView.BlazorWebViewInitialized += BlazorWebViewInitialized; _blazorWebView.BlazorWebViewInitializing += BlazorWebViewInitializing;
完整代码:
using LibraryShared;
using Microsoft.AspNetCore.Components.WebView;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Platform;
using System;
using static Microsoft.Maui.ApplicationModel.Permissions;
#if ANDROID
using AndroidX.Activity;
#endif
namespace BlazorMaui
{
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
_blazorWebView.BlazorWebViewInitialized += BlazorWebViewInitialized;
_blazorWebView.BlazorWebViewInitializing += BlazorWebViewInitializing;
}
private void BlazorWebViewInitialized(object? sender, BlazorWebViewInitializedEventArgs e)
{
#if ANDROID
if (e.WebView.Context?.GetActivity() is not ComponentActivity activity)
{
throw new InvalidOperationException($"The permission-managing WebChromeClient requires that the current activity be a '{nameof(ComponentActivity)}'.");
}
e.WebView.Settings.JavaScriptEnabled = true;
e.WebView.Settings.AllowFileAccess = true;
e.WebView.Settings.MediaPlaybackRequiresUserGesture = false;
e.WebView.Settings.SetGeolocationEnabled(true);
e.WebView.Settings.SetGeolocationDatabasePath(e.WebView.Context?.FilesDir?.Path);
e.WebView.SetWebChromeClient(new PermissionManagingBlazorWebChromeClient(e.WebView.WebChromeClient!, activity));
#endif
}
private void BlazorWebViewInitializing(object? sender, BlazorWebViewInitializingEventArgs e)
{
#if IOS || MACCATALYST
e.Configuration.AllowsInlineMediaPlayback = true;
e.Configuration.MediaTypesRequiringUserActionForPlayback = WebKit.WKAudiovisualMediaTypes.None;
#endif
}
}
}4. 其他更改
由于工程是一个共享库给多端用,先定义了一个接口用于注入服务到页面调用演示功能
public interface ITools
{
Task<string> CheckPermissionsCamera();
Task<string> TakePhoto();
Task<string> CheckPermissionsLocation();
Task<string> GetCachedLocation();
Task<string> GetCurrentLocation();
Task<string> CheckMock();
double DistanceBetweenTwoLocations();
void ShowSettingsUI();
string GetAppInfo();
}调用MAUI的API功能 BlazorMaui/Services/TestService.cs
#if WINDOWS
using Windows.Storage;
#endif
#if ANDROID
using Android.Webkit;
#endif
using BlazorShared.Services;
using System.Security.Permissions;
namespace LibraryShared
{
public class TestService : ITools
{
public string GetAppInfo() {
//读取应用信息
string name = AppInfo.Current.Name;
string package = AppInfo.Current.PackageName;
string version = AppInfo.Current.VersionString;
string build = AppInfo.Current.BuildString;
return $"{name},{version}.{build}";
}
public void ShowSettingsUI()
{
//显示应用设置
AppInfo.Current.ShowSettingsUI();
}
public async Task<string> CheckPermissionsCamera()
{
//检查权限的当前状态
PermissionStatus status = await Permissions.CheckStatusAsync<Permissions.Camera>();
//请求权限
if (status != PermissionStatus.Granted)
{
status = await Permissions.RequestAsync<Permissions.Camera>();
}
return status.ToString();
}
public async Task<string> CheckPermissionsLocation()
{
//检查权限的当前状态
PermissionStatus status = await Permissions.CheckStatusAsync<Permissions.LocationWhenInUse>();
//请求权限
if (status != PermissionStatus.Granted)
{
status = await Permissions.RequestAsync<Permissions.LocationWhenInUse>();
}
return status.ToString();
}
/// <summary>
/// 拍照
/// CapturePhotoAsync调用该方法以打开相机，让用户拍照。 如果用户拍照，该方法的返回值将是非 null 值。
/// 以下代码示例使用媒体选取器拍摄照片并将其保存到缓存目录：
/// </summary>
public async Task<string> TakePhoto()
{
await CheckPermissionsCamera();
if (MediaPicker.Default.IsCaptureSupported)
{
FileResult photo = await MediaPicker.Default.CapturePhotoAsync();
if (photo != null)
{
// save the file into local storage
string localFilePath = Path.Combine(FileSystem.CacheDirectory, photo.FileName);
using Stream sourceStream = await photo.OpenReadAsync();
using FileStream localFileStream = File.OpenWrite(localFilePath);
await sourceStream.CopyToAsync(localFileStream);
return localFilePath;
}
return "photo null";
}
return null;
}
/// <summary>
/// 获取最后一个已知位置, 设备可能已缓存设备的最新位置。
/// 使用此方法 GetLastKnownLocationAsync 访问缓存的位置（如果可用）。
/// 这通常比执行完整位置查询更快，但可能不太准确。
/// 如果不存在缓存位置，此方法将 null返回 。
/// </summary>
/// <returns></returns>
public async Task<string> GetCachedLocation()
{
await CheckPermissionsLocation();
string result = null;
try
{
Location location = await Geolocation.Default.GetLastKnownLocationAsync();
if (location != null)
{
result = $"Latitude: {location.Latitude}, Longitude: {location.Longitude}, Altitude: {location.Altitude}";
Console.WriteLine(result);
return result;
}
}
catch (FeatureNotSupportedException fnsEx)
{
// Handle not supported on device exception
result = $"not supported on device, {fnsEx.Message}";
}
catch (FeatureNotEnabledException fneEx)
{
// Handle not enabled on device exception
result = $"not enabled on device, {fneEx.Message}";
}
catch (PermissionException pEx)
{
// Handle permission exception
result = $"permission, {pEx.Message}";
}
catch (Exception ex)
{
// Unable to get location
result = $"Unable to get location, {ex.Message}";
}
return result ?? "None";
}
private CancellationTokenSource _cancelTokenSource;
private bool _isCheckingLocation;
/// <summary>
/// 获取当前位置
/// 虽然检查设备 的最后已知位置 可能更快，但它可能不准确。
/// 使用该方法 GetLocationAsync 查询设备的当前位置。
/// 可以配置查询的准确性和超时。
/// 最好是使用 GeolocationRequest 和 CancellationToken 参数的方法重载，
/// 因为可能需要一些时间才能获取设备的位置。
/// </summary>
/// <returns></returns>
public async Task<string> GetCurrentLocation()
{
await CheckPermissionsLocation();
string result = null;
try
{
_isCheckingLocation = true;
GeolocationRequest request = new GeolocationRequest(GeolocationAccuracy.Medium, TimeSpan.FromSeconds(10));
_cancelTokenSource = new CancellationTokenSource();
#if IOS
//从 iOS 14 开始，用户可能会限制应用检测完全准确的位置。
//该 Location.ReducedAccuracy 属性指示位置是否使用降低的准确性。
//若要请求完全准确性，请将 GeolocationRequest.RequestFullAccuracy 属性设置为 true
request.RequestFullAccuracy = true;
#endif
Location location = await Geolocation.Default.GetLocationAsync(request, _cancelTokenSource.Token);
if (location != null)
{
result = $"Latitude: {location.Latitude}, Longitude: {location.Longitude}, Altitude: {location.Altitude}";
Console.WriteLine(result);
return result;
}
}
catch (FeatureNotSupportedException fnsEx)
{
// Handle not supported on device exception
result = $"not supported on device, {fnsEx.Message}";
}
catch (FeatureNotEnabledException fneEx)
{
// Handle not enabled on device exception
result = $"not enabled on device, {fneEx.Message}";
}
catch (PermissionException pEx)
{
// Handle permission exception
result = $"permission, {pEx.Message}";
}
catch (Exception ex)
{
// Unable to get location
result = $"Unable to get location, {ex.Message}";
}
finally
{
_isCheckingLocation = false;
}
return result ?? "None";
}
}
}在MauiProgram.cs文件注入
builder.Services.AddSingleton<ITools, TestService>();razor
<Button Text="定位权限" OnClick="检查定位权限" />
<span>@定位权限</span><br/><br/>
<Button Text="摄像机权限" OnClick="检查摄像机权限" />
<span>@摄像机权限</span><br /><br />
<Button Text="定位" OnClick="获取定位" />
<span>@Locations</span><br /><br />
<Button Text="TakePhoto" OnClick="TakePhoto" />
<span>@PhotoFilename</span><br /><br />
<Button Text="ShowSettings" OnClick="ShowSettingsUI" />
<span>@version</span><br /><br />
@code{
[Inject] protected ITools Tools { get; set; }
private string Locations;
private string PhotoFilename;
private string version;
private string 定位权限;
private string 摄像机权限;
async Task 获取定位() => Locations = await Tools.GetCurrentLocation();
async Task TakePhoto() => PhotoFilename = await Tools.TakePhoto();
async Task 检查定位权限() => 定位权限 = await Tools.CheckPermissionsLocation();
async Task 检查摄像机权限() => 摄像机权限 = await Tools.CheckPermissionsCamera();
void ShowSettingsUI() => Tools.ShowSettingsUI();
}最终效果
项目地址
https://github.com/densen2014/BlazorMaui
https://gitee.com/densen2014/BlazorMaui
参考资料
Permissions
https://docs.microsoft.com/en-us/dotnet/maui/platform-integration/appmodel/permissions?tabs=android
Geolocation
https://docs.microsoft.com/en-us/dotnet/maui/platform-integration/device/geolocation?tabs=windows
MauiBlazorPermissionsExample
https://github.com/MackinnonBuck/MauiBlazorPermissionsExample
关联项目
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