Blazor 8 Web App集成Azure B2C：求完整配置指南及参考示例

一、核心配置步骤（从无授权模板开始） #

• 安装依赖包：在项目中安装Microsoft.AspNetCore.Authentication.OpenIdConnect和Microsoft.Identity.Web NuGet包
• 配置appsettings.json：添加Azure B2C相关参数，示例如下：

  "AzureAdB2C": {
    "Instance": "https://你的租户域名.b2clogin.com/",
    "Domain": "你的租户域名.onmicrosoft.com",
    "ClientId": "你的应用客户端ID",
    "SignedOutCallbackPath": "/signout/B2C_1_你的注册登录策略名",
    "SignUpSignInPolicyId": "B2C_1_你的注册登录策略名"
  }
  

• 配置Program.cs：添加身份验证服务、启用授权中间件，保护Blazor路由
• 组件授权配置：在App.razor中添加<CascadingAuthenticationState>和<AuthorizeRouteView>，对需要授权的页面做访问控制

二、Program.cs核心配置示例 #

var builder = WebApplication.CreateBuilder(args);

// 添加身份验证服务
builder.Services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
    .AddMicrosoftIdentityWebApp(builder.Configuration.GetSection("AzureAdB2C"))
    .EnableTokenAcquisitionToCallDownstreamApi()
    .AddInMemoryTokenCaches();

// 添加MVC与Blazor相关服务
builder.Services.AddControllersWithViews()
    .AddMicrosoftIdentityUI();
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor()
    .AddMicrosoftIdentityConsentHandler();

var app = builder.Build();

// 配置请求管道
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();

// 映射路由端点
app.MapRazorPages();
app.MapControllers();
app.MapBlazorHub();
app.MapFallbackToPage("/_Host");

app.Run();

三、自定义声明映射处理 #

如果需要解析自定义策略中的自定义声明，可在OpenID Connect配置中添加声明转换逻辑：

.AddMicrosoftIdentityWebApp(options =>
{
    builder.Configuration.Bind("AzureAdB2C", options);
    options.Events = new OpenIdConnectEvents
    {
        OnTokenValidated = context =>
        {
            // 示例：映射自定义声明extension_CustomClaim到本地声明CustomClaim
            var customClaim = context.Principal.FindFirst("extension_CustomClaim");
            if (customClaim != null)
            {
                context.Principal.Identities.First().AddClaim(new Claim("CustomClaim", customClaim.Value));
            }
            return Task.CompletedTask;
        }
    };
})

内容的提问来源于stack exchange，提问作者Pritorian