HttpContext.Current為空匯總

1. async異步模式下為空

解決辦法：

<httpRuntime targetFramework="4.5" />

或者：

In your appSettings, set aspnet:UseTaskFriendlySynchronizationContext to true.

2. 在非Http請求線程中使用爲空

示例代碼——將主線程的HttpContext傳遞進去：

var httpContext = HttpContext.Current;

TaskWithDuration = new Task<long>(() =>
{
    var sw = new Stopwatch();
    sw.Start();

    HttpContext.Current = httpContext;

    action();

    sw.Stop();

    return sw.ElapsedMilliseconds;
});

REF:

[HttpContext.Current並不是無處不在] http://www.cnblogs.com/fish-li/archive/2013/04/06/3002940.html