'context.Request' 引发了 'System.Web.HttpException' 类型的异常

Question

我正在尝试在 Global.asax Application_Start() 事件中使用访问 HTTPContext。

        var context = HttpContext.Current;
        if (context != null)
        {
            if (context.Request != null) //Getting error here
            {
                  .....
            }
        }

访问 context.Request 时出现 'context.Request' threw an exception of type 'System.Web.HttpException' 异常。

在这种情况下 context.Request 不是 null 但它抛出异常。

我使用以下代码来识别 Request 属性 是否存在：

context.GetType().GetProperty("Request");

我得到了以下回复。

{System.Web.HttpRequest Request}
    Attributes: None
    CanRead: true
    CanWrite: false
    CustomAttributes: Count = 0
    DeclaringType: {Name = "HttpContext" FullName = "System.Web.HttpContext"}
    GetMethod: {System.Web.HttpRequest get_Request()}
    IsSpecialName: false
    MemberType: Property
    MetadataToken: 385876876
    Module: {System.Web.dll}
    Name: "Request"
    PropertyType: {Name = "HttpRequest" FullName = "System.Web.HttpRequest"}
    ReflectedType: {Name = "HttpContext" FullName = "System.Web.HttpContext"}
    SetMethod: null

I am not sure how to confirm if context.Request exists and is not null ?

Answer 1

来自the documentation：

ASP.NET will throw an exception if you try to use this property when the HttpRequest object is not available. For example, this would be true in the Application_Start method of the Global.asax file, or in a method that is called from the Application_Start method. At that time no HTTP request has been created yet.

Application_Start 并不意味着处理特定请求，因此您需要将您正在做的事情转移到不同事件的处理程序中，例如 BeginRequest.

Answer 2

public class Global : HttpApplication
{
   private static HttpRequest initialRequest;

   static Global()
   {
      initialRequest = HttpContext.Current.Request;       
   }

   void Application_Start(object sender, EventArgs e)
   {
      //access the initial request here

    }

您可以在此处使用 Application_Start 事件。静态类型是在其 HTTPContext 中使用请求创建的，允许您存储它并立即在 Application_Start 事件中重用它。