C＃-如何更改辅助线程中进度条的值

Question

In my program I import millions of records to a SQL Server database with the help of SqlBulkCopy class. Since this is a heavy lifting it takes quite some time. While the process goes on I want to show the progress in a progressbar control. To be notified for the rows copied I've done this:

.......
bulkCopy.NotifyAfter = 2000;
bulkCopy.SqlRowsCopied += new SqlRowsCopiedEventHandler(bulkCopy_SqlRowsCopied);
.......

Now in the bulkCopy_SqlRowsCopied method I want to change the value of the progress bar. But I think I need to make it on a seperate thread. How can I do this?

Answer 1

You can have one extension class, like

public static class ControlExtensions
{
    public static void Invoke(this Control control, Action action)
    {
        if (control.InvokeRequired) control.Invoke(new MethodInvoker(action), null);
        else action.Invoke();
    }
 }

Now when ever and where ever you want to update status of progress bar, you can do

progressBar.Invoke(() => { progressBar.PerformStep(); };

Hope this works for you.

Answer 2

You could execute your copy in a BackgroundWorker and use ReportProgress to update your progressbar...
You can find an example at http://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx .

The use of a BackgroundWorker for time-consuming operations is good because your UI (with the main thread) is free to be updated/refreshed, making user experience better.

Answer 3

For non-collection properties WPF will marshall the value on to the UI thread for you. So if you have a ViewModel with a progress property that raises the PropertyChanged event you can bind your ProgressBar to the ProgressBar.

For this to work, your ViewModel instance should not be a DependencyObject (but that is a bad idea for so many reasons). This way you can reference it from your background thread and set the Progress property.

Answer 4

Using the Invoke() Method of the ProgressBar Control in your EventHandler "bulkCopy_SqlRowsCopied", make sure you set the NotifyAfter property of the SqlBulkCopy class to an amount that would reflect some form of percentage.

Now in the bulkCopy_SqlRowsCopied method I want to change the value of the progress bar. But I think I need to make it on a seperate thread. How can I do this?

If you are using .Net 4.0 you could start your bulk copy in a Task, other versions you could use the ThreadPool, create your own thread

Task.Factory.StartNew(MyBulkCopyMethod);