Blazor WebAssembly中AuthorizationMessageHandler无法解析IAccessTokenProvider求助

我是Blazor技术新手，开发.NET 6 Blazor WebAssembly客户端项目时，遇到AuthorizationMessageHandler无法解析类型为Microsoft.AspNetCore.Components.WebAssembly.Authentication.IAccessTokenProvider的服务的异常。

已安装的包 #

<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="6.0.13" />
<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Authentication" Version="6.0.13" />
<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="6.0.13" PrivateAssets="all" />
<PackageReference Include="Microsoft.Extensions.Http" Version="6.0.0" />

GraphAuthorizationMessageHandler.cs代码 #

public class GraphAuthorizationMessageHandler : AuthorizationMessageHandler
{
    public GraphAuthorizationMessageHandler(IAccessTokenProvider provider,
        NavigationManager navigation, IConfiguration config)
        : base(provider, navigation)
    {
        ConfigureHandler(
            authorizedUrls: new[] { config.GetSection("MicrosoftGraph")["BaseUrl"] },
            scopes: config.GetSection("MicrosoftGraph:Scopes").Get<List<string>>());
    }
}

Program.cs代码 #

using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using MySample.WebAssembly.Client;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

builder.Services.AddTransient<GraphAuthorizationMessageHandler>();

builder.Services.AddHttpClient("GraphAPI",
        client => client.BaseAddress = new Uri(
            builder.Configuration.GetSection("MicrosoftGraph")["BaseUrl"]))
    .AddHttpMessageHandler<GraphAuthorizationMessageHandler>();

await builder.Build().RunAsync();

异常信息 #

Unhandled exception rendering component: Unable to resolve service for type 'Microsoft.AspNetCore.Components.WebAssembly.Authentication.IAccessTokenProvider' while attempting to activate 'MySample.WebAssembly.Client.GraphAuthorizationMessageHandler'.

问题核心是DI容器中未注册Blazor WebAssembly认证服务，IAccessTokenProvider由Microsoft.AspNetCore.Components.WebAssembly.Authentication包提供，必须通过专属的认证注册方法注入容器。

步骤1：添加认证服务注册 #

在Program.cs中，注册HttpClient和GraphAuthorizationMessageHandler之前，添加认证服务代码。根据你使用的认证类型选择对应方法：

• 若使用OIDC认证（如微软账号、Azure AD）：

builder.Services.AddOidcAuthentication(options =>
{
    // 从appsettings.json绑定认证配置，如Authority、ClientId等
    builder.Configuration.Bind("AzureAd", options.ProviderOptions);
});

• 若配合ASP.NET Core Identity Server使用API授权：

builder.Services.AddApiAuthorization();

步骤2：调整代码顺序 #

确保认证服务注册在HttpClient和消息处理器之前，修改后的完整Program.cs示例：

using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Microsoft.AspNetCore.Components.WebAssembly.Authentication;
using MySample.WebAssembly.Client;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

// 先注册认证服务
builder.Services.AddOidcAuthentication(options =>
{
    builder.Configuration.Bind("AzureAd", options.ProviderOptions);
});

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

builder.Services.AddTransient<GraphAuthorizationMessageHandler>();

builder.Services.AddHttpClient("GraphAPI",
        client => client.BaseAddress = new Uri(
            builder.Configuration.GetSection("MicrosoftGraph")["BaseUrl"]))
    .AddHttpMessageHandler<GraphAuthorizationMessageHandler>();

await builder.Build().RunAsync();

说明 #

AddOidcAuthentication或AddApiAuthorization会自动注册IAccessTokenProvider及其他认证相关服务，让DI容器能找到该服务并注入到GraphAuthorizationMessageHandler中。同时需确保appsettings.json中配置了正确的认证参数（如Authority、ClientId），参数配置可参考对应认证服务的官方文档要求。

内容的提问来源于stack exchange，提问作者Ziggler