Question

我有一个WinForm加载方法需要很长时间来收集一些数据才能显示给用户。

当此方法正在执行时，我会显示一个带有大字体且带有“正在加载”字样的表单。

但是，有时会出现此错误并且“正在加载”进度表单未关闭，最终我的整个应用程序将退出：

创建窗口句柄时出错。在System.Windows.Forms.NativeWindow.CreateHandle（CreateParams cp）

在我在load方法中执行代码时，是否有更好的方法来显示我的进度/加载表单？

这是我的代码：

//I launch a thread here so that way the Progress_form will display to the user
//while the Load method is still executing code.  I can not use .ShowDialog here
//or it will block.

//Progress_form displays the "Loading" form    
Thread t = new Thread(new ThreadStart(Progress_form));  

t.SetApartmentState(System.Threading.ApartmentState.STA);
t.IsBackground = true;
t.Start();

//This is where all the code is that gets the data from the database.  This could
//take upwards of 20+ seconds.

//Now I want to close the form because I am at the end of the Load Method                         

try
{
   //abort the Progress_form thread (close the form)
   t.Abort();
   //t.Interrupt();
}
catch (Exception)
{
}

Answer 1

BackgroundWorker是在不锁定UI线程的情况下执行长时间运行操作的好方法。

使用以下代码启动BackgroundWorker并显示加载表单。

// Configure a BackgroundWorker to perform your long running operation.
BackgroundWorker bg = new BackgroundWorker()
bg.DoWork += new DoWorkEventHandler(bg_DoWork);
bg.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bg_RunWorkerCompleted);

// Start the worker.
bg.RunWorkerAsync();

// Display the loading form.
loadingForm = new loadingForm();
loadingForm.ShowDialog();

这将导致在后台线程上执行以下方法。请注意，您无法从此线程操纵UI。试图这样做会导致异常。

private void bg_DoWork(object sender, DoWorkEventArgs e)
{
    // Perform your long running operation here.
    // If you need to pass results on to the next
    // stage you can do so by assigning a value
    // to e.Result.
}

当长时间运行的操作完成时，将在UI线程上调用此方法。您现在可以安全地更新任何UI控件。在您的示例中，您需要关闭加载表单。

private void bg_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // Retrieve the result pass from bg_DoWork() if any.
    // Note, you may need to cast it to the desired data type.
    object result = e.Result;

    // Close the loading form.
    loadingForm.Close();

    // Update any other UI controls that may need to be updated.
}

Answer 2

我会把你在load方法中的代码放到一个线程中。在表单的某处设置一个进度条，并在收集数据的代码的关键阶段递增它 - 注意不要在线程本身中执行此操作，即不要在单独的线程中篡改ui元素，你将会需要使用委托来调用它们。

Answer 3

我已经在.NET 4.0上成功测试了这个。（WinForms）我合理地确定这可以在.NET 4.0+上运行，并且应该是一个有用的代码片段，可以在大多数需要在流程结束时关闭表单的项目中重用。

private void SomeFormObject_Click(object sender, EventArgs e)
{
    myWait = new YourProgressForm();//YourProgressForm is a WinForm Object
    myProcess = new Thread(doStuffOnThread);
    myProcess.Start();
    myWait.ShowDialog(this);
}

private void doStuffOnThread()
{
    try
    {
        //....
        //What ever process you want to do here ....
        //....

        if (myWait.InvokeRequired) {
            myWait.BeginInvoke( (MethodInvoker) delegate() { closeWaitForm(); }  );
        }
        else
        {
            myWait.Close();//Fault tolerance this code should never be executed
        }
    }
    catch(Exception ex) {
        string exc = ex.Message;//Fault tolerance this code should never be executed
    }
}

private void closeWaitForm() {
    myWait.Close();
    MessageBox.Show("Your Process Is Complete");
}

在方法执行代码时显示进度表单的最佳方法？

3 个答案: