当用户在Blazor WASM应用程序中的会话过期时，我们需要以某种方式通知他们并引导他们重新登录。以下是一种可能的解决方案。

1. 创建SessionService类来管理会话状态。

public class SessionService
{
    private readonly HttpClient httpClient;
    private readonly NavigationManager navigationManager;
    private CancellationTokenSource cancellationTokenSource;

    private bool isSessionExpired;

    public event Func SessionExpired;

    public bool IsSessionExpired
    {
        get { return isSessionExpired; }
        private set
        {
            if (isSessionExpired != value)
            {
                isSessionExpired = value;

                if (value)
                {
                    OnSessionExpired();
                }
            }
        }
    }

    public SessionService(HttpClient httpClient, NavigationManager navigationManager)
    {
        this.httpClient = httpClient;
        this.navigationManager = navigationManager;
        this.cancellationTokenSource = new CancellationTokenSource();

        this.httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    }

    public async Task CheckSession()
    {
        var request = new HttpRequestMessage(HttpMethod.Get, "api/Session/CheckSession");

        try
        {
            var response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationTokenSource.Token);

            if (response.IsSuccessStatusCode)
            {
                IsSessionExpired = false;
                return true;
            }

            if (response.StatusCode == HttpStatusCode.Unauthorized)
            {
                IsSessionExpired = true;
                return false;
            }

            // Handle other HTTP status codes if necessary...
        }
        catch (OperationCanceledException)
        {
            // The request was cancelled, likely due to a timeout
        }

        return false;
    }

    public void CancelSessionCheck()
    {
        cancellationTokenSource.Cancel();
        IsSessionExpired = true;
    }

    private async void OnSessionExpired()
    {
        if (SessionExpired != null)
        {
            await SessionExpired.Invoke();
        }
    }
}

2. 在Blazor中注入SessionService类并在App.razor文件中添加以下代码。

@inject SessionService SessionService


    
        
            
        
        
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@if (SessionService.IsSessionExpired)
{
    

        Your session has expired. Please click here to login again.
        
            ×
        
    
}

3. 创建一个名为SessionController的ASP.NET Core Web API Controller，其中包含一个名为CheckSession的操作，该操作用于检查用户的会话状态。

[ApiController]
[Route("api/[controller]")]
public class SessionController : ControllerBase
{
    [HttpGet("CheckSession")]
    public IActionResult CheckSession()
    {
        if (User.Identity.IsAuthenticated)
        {
            return Ok();
        }

        return Unauthorized();
    }
}

4. 在应用程序中使用SessionService类来检