从ASP.NET中的静态类更新控件的值

Question

Say that I have an ASP.NET page with a Label control and the following static class which executes a scheduled job:

public static class Job
{
    // The Execute method is called by a scheduler and must therefore 
    // have this exact signature (i.e. it cannot take any paramters).
    public static string Execute()
    {
        // Do work
    }
}

When the job is done, the execute method should update the value of the Label control on the page.

I've done some research and the only way seems to be to use HttpContext.Current.CurrentHandler. However, this is undesirable for me since it can potentially return null.

Since the Execute method cannot take any parameters (see comment), passing the Page instance as an argument is not an option.

Is there any other way to update the control from the static class?

NOTE: the Execute method must be static because I'm creating an EPiServer scheduled job, which requires a static Execute method (that doesn't take any parameters).

Answer 1

If the job is not executed synchronously (or even if it is), I think that you may want to consider the order of control.

What I suggest in a case like this is a structure similar to the following:

1) The web page issues the request for the job

2) Somewhere, a unique reference to the job is created and stored (such as GUID or an identity column in a database table)

3) The job is executed asynchronously by code-behind and then the unique identifier is returned to the web page.

4) The web page, on startup, initiates a javascript method (using window.timeout, for example) that on a regular basis, issues an ajax query to the web server to check on the status of the job.

5) When the job is complete, it updates the global reference with the appropriate information.

6) When the javascript sees that the job is complete, it updates the label.

This process allows the user to carry on with other work if necessary and not have to worry about timeouts due to long postback times, etc.

For your specific scenario, you could add a GUID property to the Job class (which would be passed back to the client).

When Execute is complete, you could add this GUID to a static collection (ie Dictionary<Guid, string> ) which the ajax request would check (the string value could store status or completion information).

When the ajax request fires, it would check this static collection and, when it finds its job, remove it and return the value to the caller.

Answer 2

尝试使用全局变量（静态）或通过Execute（）方法引发事件。

Answer 3

You can create a static property that is updated by your Execute method and bind the Text property of the Label to the static property in the aspx's OnInit method, Label.Text = Job.StaticProperty, if you need a somewhat dynamic response you could use the Ajax Timer Control to call a method on the aspx page to return the same static value from the aspx Page.

public static class Job 
{ 
    public static string UpdatedValue { get; private set; } // Or whatever the property is you wish to expose.

    // The Execute method is called by a scheduler and must therefore  
    // have this exact signature (i.e. it cannot take any paramters). 
    public static string Execute() 
    { 
        // Do work
        Job.UpdatedValue = "Execute Completed";
    } 
} 


protected override OnInit(EventArgs e)
{
    base.OnInit(e);
    this.TextLabel.Text = Job.UpdatedValue;
}


// Using MSDN basic sample
protected void Timer1_Tick(object sender, EventArgs e)
{
    this.TextLabel.Text = Job.UpdatedValue;
}