dependency-injection - 如何在 Blazor 类中注入(inject)服务(AuthenticationStateProvider)

Question

我正在努力在 Blazor 服务器的类中注入(inject)服务 (AuthenticationStateProvider)。如果我在 Razor 组件中执行此操作，则非常简单:
@inject AuthenticationStateProvider AuthenticationStateProvider
进而

private async Task LogUsername()
{
    var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
    var user = authState.User;

    if (user.Identity.IsAuthenticated)
    {
       ClientMachineName = $"{user.Identity.Name}";
    }
    else
    {
       ClientMachineName = "Unknown";
    }
} 

但是我需要这样做，即在类而不是 Razor 组件中检索经过身份验证的用户机器名称。

我试过例如:

[Inject]
AuthenticationStateProvider AuthenticationStateProvider { get; set; }

public async Task LogUsername()
{        
    var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
    var user = authState.User;

    if (user.Identity.IsAuthenticated)
    {
        ClientMachineName = $"{user.Identity.Name}";
    }
    else
    {
        ClientMachineName = "Unknown";
    }
}

但这似乎不起作用。

任何帮助将非常感激。

Answer 1

使用 Blazor 服务器(.Net Core 3)，这对我有用:

public class AuthTest
{
    private readonly AuthenticationStateProvider _authenticationStateProvider;

    public AuthTest(AuthenticationStateProvider authenticationStateProvider)
    {
        _authenticationStateProvider = authenticationStateProvider;
    }

    public async Task<IIdentity> GetIdentity()
    {
        var authState = await _authenticationStateProvider.GetAuthenticationStateAsync();
        var user = authState.User;
        return user.Identity;
    }
}

您需要在 Startup.ConfigureServices 中向 ASP.Net Core DI 注册它。 :

services.AddScoped<AuthTest>();

然后将其注入(inject)您的 .razor页:

@page "/AuthTest"
@inject AuthTest authTest;
<button @onclick="@LogUsername">Write user info to console</button>

@code{
    private async Task LogUsername()
    {
        var identity= await authTest.IsAuthenticated();
        Console.WriteLine(identity.Name);
    }

您应该看到写入 ASP.Net 输出控制台的登录用户名。
更新
如果您想从一个单独的类中获取当前登录的用户并且您没有将其注入(inject)到 blazor 页面中，请遵循指南 here