1. 创建CustomAuthenticationStateProvider类，并继承自ServerAuthenticationStateProvider：

public class CustomAuthenticationStateProvider : ServerAuthenticationStateProvider
{
    // 构造函数
    public CustomAuthenticationStateProvider(NavigationManager navigationManager) : base(navigationManager)
    {
    }

    // 在此自定义身份验证状态
    public override Task GetAuthenticationStateAsync()
    {
        // 自定义身份验证逻辑
        var identity = new ClaimsIdentity(new[]
        {
            new Claim(ClaimTypes.Name, "username"),
        }, "Custom");

        return Task.FromResult(new AuthenticationState(new ClaimsPrincipal(identity)));
    }
}

2. 在Startup.cs中将默认的ServerAuthenticationStateProvider替换为CustomAuthenticationStateProvider：

public void ConfigureServices(IServiceCollection services)
{
    services.AddAuthentication();
    services.AddScoped();
    services.AddRazorPages();
    services.AddServerSideBlazor();

    services.AddAuthorization(options =>
    {
        options.AddPolicy("CustomPolicy", builder =>
        {
            // 自定义策略逻辑
        });
    });

    services.AddScoped();
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseAuthentication();
    app.UseAuthorization();
    app.UseRouting();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapBlazorHub();
        endpoints.MapFallbackToPage("/_Host");
    });
}

3. 在组件中使用身份验证状态：

@page "/"
@using Microsoft.AspNetCore.Components.Authorization
@inject AuthenticationStateProvider AuthenticationStateProvider


    
        
Hello, @context.User.Identity.Name!
    
    
        
You are not authorized to access this page.
    


@code {
    private AuthenticationState authState;

    protected override async Task OnInitializedAsync()
    {
        authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
    }
}