webmvc中使用异步，出现HttpContext.Current为null的情况解决

原因：子线程不能够得到主线程的HttpContext.Current数据

解决方案  采用缓存 共享数据

再异步方法之前  

  HttpContext context = System.Web.HttpContext.Current;
            HttpRuntime.Cache.Insert("context", context);

 

 

异步方法中调用

   HttpContext context = HttpContext.Current;
            if (context == null) {
                context = HttpRuntime.Cache.Get("context") as HttpContext;
            }