为什么HttpContext.Current在asp.net mvc中的用户定义类中始终为null？ [英] Why HttpContext.Current always null in user defined class in asp.net mvc ?

问题描述

我创建了一个名为MyLongRunningClass的类，其中包含一个方法：

  public   string  ProcessLongRunningAction（IEnumerable< HttpPostedFileBase>文件，字符串 id）
 {
 < span class =code-keyword> int  currentIndex =  0 ; 
  foreach （HttpPostedFileBase文件 in  files）
 {
 currentIndex ++; 
  lock （syncRoot）
 {
   string 路径= HttpContext.Current.Server.MapPath（ 〜// Content // images // + file .FileName）;   //  此处创建了Excecption ........  
 file.SaveAs（path）; 
} 
 Thread.Sleep（ 300 ）; 
} 
  return  id; 
} 

从控制器调用此方法，并使用要保存在images目录中的文件列表。每当执行HttpContext.Current.Server.MapPath（〜// Content // images //+ file.FileName）时，抛出NullReferenceException，并且HttpContext.Current始终为null。当我使用session时会发生同样的事情。我不知道我有什么不对劲。我马上需要帮助。请告诉我该怎么做，示例代码更明显。

感谢.......提前

解决方案

First确保你在指定的路径中有图像文件..

并尝试这样的事情，

 Server.MapPath（ @ 〜/ Content / images / + file.FileName）; 

I've created a class named "MyLongRunningClass" that contain a method bellow:

public string ProcessLongRunningAction(IEnumerable<HttpPostedFileBase> files ,string id)
        {
            int currentIndex = 0;
            foreach (HttpPostedFileBase file in files)
            {
                currentIndex++;
                lock(syncRoot)
                {                
                 string path=HttpContext.Current.Server.MapPath("~//Content//images       //"+file.FileName);//Excecption is created here........
                  file.SaveAs(path);
                }
              Thread.Sleep(300);
            }
            return id;
        }

From the controller this method is called with list of file to save in images directory. whenever HttpContext.Current.Server.MapPath("~//Content//images//"+file.FileName) is executed NullReferenceException thrown, and HttpContext.Current is always null. Same thing happen when I use session. I don't know whats wrong with me. I need help Immediately. please tell me what should i do, sample code is more appreciable.
THANKS.......IN ADVANCE

解决方案

First make sure, you have image file in the specified path..
And try something like this,

Server.MapPath(@"~/Content/images/"+file.FileName);

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