Does asp.net MVC have Application variables?

问题

I am busy converting a web application to MVC and have some information saved to Application variables used across multiple tenants/accounts to make things a bit more efficient.

I realise the point of MVC is to keep things as stateless as possible, Sesion State obviously makes sense to have and exists in MVC but we dont want to just convert Application to Session variables as we would rather have something more global and more secure. Do MVC applications have Application Variables? I have seen some examples where caching is used? Is this now standard and How robust/secure is this compared to Application/Session State?

回答1:

Yes, you can access Application variables from .NET MVC. Here's how:

System.Web.HttpContext.Current.Application.Lock();
System.Web.HttpContext.Current.Application["Name"] = "Value";
System.Web.HttpContext.Current.Application.UnLock();

回答2:

Session state or the Cache are better choices. They are mockable in MVC and are designed to store session and application-scoped data.

Static classes seems like a popular choice here. However static classes create dependencies between your types and make versioning/testing harder. Its also a bit of an odd pattern to use in a framework that is designed to break apart these kinds of dependencies. For instance, the standard ASP.NET framework is riddled with statics and sealed types. These are all replaced with mock-able instances.

"Secure" is a bit unclear in this context. Exactly what do you mean by "secure?"

回答3:

I implemented something like below as an Extension for Global state variable. I put things like Site title,Service Endpoints, authorized roles

public static class ApplicationStateExtension
 {
    public static T GetSetApplicationState<T>(this HttpApplicationState appState, string objectName, object objectValue = null, int syncCheckMinutes = 0)
    {
        T retVal = default(T);
        appState.Lock();
        if (appState[objectName + "LastSync"] == null || DateTime.Now.Subtract(((DateTime)appState[objectName + "LastSync"])).TotalMinutes >= syncCheckMinutes)
        {
            appState[objectName + "LastSync"] = DateTime.Now;

            if (objectValue != null)
                appState[objectName] = objectValue;
        }
        if (appState[objectName] != null)
            retVal = (T)appState[objectName];
        appState.UnLock();
        return retVal;
    }
    public static object GetSetApplicationState(this HttpApplicationState appState, string objectName, object objectValue = null, int syncCheckMinutes = 0)
    {
        object retVal = null;
        appState.Lock();
        if (appState[objectName + "LastSync"] == null || DateTime.Now.Subtract(((DateTime)appState[objectName + "LastSync"])).TotalMinutes >= syncCheckMinutes)
        {
            appState[objectName + "LastSync"] = DateTime.Now;

            if (objectValue != null)
                appState[objectName] = objectValue;
        }
        if (appState[objectName] != null)
            retVal = appState[objectName];
        appState.UnLock();
        return retVal;
    }
    public static void SetApplicationState(this HttpApplicationState appState, string objectName, object objectValue, int syncCheckMinutes = 0)
    {
        appState.Lock();
        if (appState[objectName + "LastSync"] == null || DateTime.Now.Subtract(((DateTime)appState[objectName + "LastSync"])).TotalMinutes >= syncCheckMinutes)
        {
            appState[objectName + "LastSync"] = DateTime.Now;
            appState[objectName] = objectValue;
        }
        appState.UnLock();
    }
    public static object GetApplicationState(this HttpApplicationState appState, string objectName)
    {
        object retVal = null;
        appState.Lock();
        if (appState[objectName] != null)
            retVal = appState[objectName];
        appState.UnLock();
        return retVal;
    }
    public static T GetApplicationState<T>(this HttpApplicationState appState, string objectName)
    {
        T retVal = default(T);
        appState.Lock();
        if (appState[objectName] != null)
            retVal = (T)appState[objectName];
        appState.UnLock();
        return retVal;
    }
}

So I can set them from Global.asax.cs something like this

Application.SetApplicationState("UISiteTitle",paramHelper.GetUIConfigXML<XMLParams.UISiteOptions>("UISiteOptions")
                .SiteOptionCollection.Where(v => v.name.Equals("title", StringComparison.InvariantCultureIgnoreCase)).FirstOrDefault().value););

or

var uiPermissions = Application.GetSetApplicationState<XMLParams.UIPermissions>("UIPermissions", paramHelper.GetUIConfigXML<XMLParams.UIPermissions>("UIPermissions"), 30);

回答4:

Make a static class?

回答5:

You can declare Application variables in Application_Start like this:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RouteConfig.RegisterRoutes(RouteTable.Routes);

    var e = "Hello";
    Application["value"] = e;
}

To access this on controller write:

string appVar = HttpContext.Application["value"] as string;

回答6:

Do they have Application Variables? Yes, MVC is a framework that sits on top of the normal asp.net framework.

I would however create a static class that uses a cache store as it's backing.

来源：https://stackoverflow.com/questions/2266533/does-asp-net-mvc-have-application-variables