How can I get the value of a session variable inside a static method?

问题

I am using ASP.NET page methods with jQuery.... How do I get the value of a session variable inside a static method in C#?

protected void Page_Load(object sender, EventArgs e)
{
    Session["UserName"] = "Pandiya";
}

[WebMethod]
public static string GetName()
{
    string s = Session["UserName"].ToString();
    return s;
}

When I compile this I get the error:

An object reference is required for the non-static field, method, or property 'System.Web.UI.Page.Session.get'`

回答1:

HttpContext.Current.Session["..."]

HttpContext.Current gets you the current ... well, Http Context; from which you can access: Session, Request, Response etc

回答2:

If you haven't changed thread, you can use HttpContext.Current.Session, as indicated by jwwishart.

HttpContext.Current returns the context associated with the thread. Obviously this means you can't use it if you've started a new thread, for example. You may also need to consider thread agility - ASP.NET requests don't always execute on the same thread for the whole of the request. I believe that the context is propagated appropriately, but it's something to bear in mind.

回答3:

Try this:

HttpContext.Current.Session["UserName"].ToString();

回答4:

You can access the current Session via HttpContext.Current - a static property through which you can retrieve the HttpContext instance that applies to the current web request. This is a common pattern in static App Code and static page methods.

string s = (string)HttpContext.Current.Session["UserName"];

The same technique is used to access the Session from within ASMX web methods decorated with [WebMethod(EnableSession = true)] because whilst such methods are not static they do not inherit from Page and thus do not have direct access to a Session property.

Static code can access the Application Cache in the same way:

string var1 = (string)HttpContext.Current.Cache["Var1"];

If the static code is inside another project we need to reference System.Web.dll. However, in this case it is generally best to avoid such a dependency because if the code is called from outside of an ASP.NET context HttpContext.Current will be null, for obvious reasons. Instead, we can require a HttpSessionState as an argument (we'll still need the reference to System.Web of course):

public static class SomeLibraryClass
{
    public static string SomeLibraryFunction(HttpSessionState session)
    {
       ...
    }
}

Call:

[WebMethod]
public static string GetName()
{
    return SomeLibraryClass.SomeLibraryFunction(HttpContext.Current.Session);
}

来源：https://stackoverflow.com/questions/2577183/how-can-i-get-the-value-of-a-session-variable-inside-a-static-method

标签

ASP.NET

methods

static

session-variables