HttpContext.Current 在 Identity Framework 的方法中为 null

在Identity Framework的开发过程中，我们常常会遇到HttpContext.Current为null的情况。HttpContext.Current是ASP.NET中的一个静态属性，用于获取当前请求的上下文信息。然而，当我们在Identity Framework的方法中使用HttpContext.Current时，有时候会发现它的值为null，这给我们的开发工作带来了一些困扰。

csharp
var httpRequest = new HttpRequest("", "http://dummyurl.com", "");
var stringWriter = new StringWriter();
var httpResponce = new HttpResponse(stringWriter);
var httpContext = new HttpContext(httpRequest, httpResponce);
HttpContext.Current = httpContext;

csharp
var currentContext = HttpContext.Current;
await Task.Run(() =>
{
    // 异步操作
    // ...
}).ContinueWith(task =>
{
    HttpContext.Current = currentContext;
    // 执行完成后的操作
});

csharp
public class CustomHttpModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.BeginRequest += (sender, e) =>
        {
            HttpContext.Current.Items["OriginalHttpContext"] = HttpContext.Current;
        };
        context.EndRequest += (sender, e) =>
        {
            HttpContext.Current = HttpContext.Current.Items["OriginalHttpContext"] as HttpContext;
        };
    }
    // 其他方法...
}

csharp
public class UserController : Controller
{
    public ActionResult Index()
    {
        var currentUser = GetCurrentUser();
        // 其他操作...
        return View();
    }
    private ApplicationUser GetCurrentUser()
    {
        if (HttpContext.Current == null)
        {
            // 在非Web请求中创建HttpContext对象
            var httpRequest = new HttpRequest("", "http://dummyurl.com", "");
            var stringWriter = new StringWriter();
            var httpResponce = new HttpResponse(stringWriter);
            var httpContext = new HttpContext(httpRequest, httpResponce);
            HttpContext.Current = httpContext;
        }
        var userManager = new ApplicationUserManager(new UserStore(new ApplicationDbContext()));
        var userId = HttpContext.Current.User.Identity.GetUserId();
        return userManager.FindById(userId);
    }
}