c# - 为什么设置表单的 enabled 属性会使应用程序崩溃？

Question

private void launchbutton_Click(object sender, EventArgs e)
    {
        launchbutton.Enabled = false;
        Process proc = new Process();
        proc.EnableRaisingEvents = true;
        proc.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
        //The arguments/filename is set here, just removed for privacy.
        proc.Exited += new EventHandler(procExit);
        proc.Start();
    }

    private void procExit(object sender, EventArgs e)
    {
        MessageBox.Show("YAY","WOOT");
        Thread.Sleep(2000);
        launchbutton.Enabled = true;
    }

退出创建的进程 2 秒后，我的程序崩溃了。为什么？

Answer 1

您正在与创建该控件的线程(主 UI 线程)不同的线程上修改 winform 控件。 Winform 控件不是线程安全的，如果您从创建它的线程以外的任何线程修改它们的状态，通常会引发异常。

您可以使用窗体或控件对象上的 InvokeRequired 属性和 BeginInvoke 方法来完成此操作。

例如，像这样:

    private void procExit(object sender, EventArgs e)
    {
        MessageBox.Show("YAY", "WOOT");
        Thread.Sleep(2000);
        // ProcessStatus is just a class I made up to demonstrate passing data back to the UI
        processComplete(new ProcessStatus { Success = true });
    }

    private void processComplete(ProcessStatus status)
    {
        if (this.InvokeRequired)
        {
            // We are in the wrong thread!  We need to use BeginInvoke in order to execute on the correct thread.
            // create a delegate pointing back to this same function, passing in the same data
            this.BeginInvoke(new Action<ProcessStatus>(this.processComplete), status);
        }
        else
        {
            // check status info
            if (status.Success)
            {
                // handle success, if applicable
            }
            else
            {
                // handle failure, if applicable
            }

            // this line of code is now safe to execute, because the BeginInvoke method ensured that the correct thread was used to execute this code.
            launchbutton.Enabled = true;
        }
    }