在调用Application.Restart之前,先在ApplicationContext中处理表单
本文关键字:ApplicationContext 处理 表单 先在 调用 Application Restart 之前 | 更新日期: 2023-09-27 18:29:49
我有一个winforms应用程序,它使用自定义应用程序上下文,该上下文提供了在系统托盘中运行应用程序的框架。
public partial class MyApplicationContext : ApplicationContext
{
private IContainer components;
private NotifyIcon notifyIcon = null;
/// the main application form, which may never be shown
private AppForm appForm = null;
public MyApplicationContext()
{
components = new System.ComponentModel.Container();
notifyIcon = new NotifyIcon(components)
{
ContextMenuStrip = new ContextMenuStrip(),
Icon = Properties.Resources.icon2a,
Text = "Application",
Visible = true
};
appForm = new AppForm();
}
}
应用程序监视配置文件的更改,并在必要时重新启动自己。
private void requestRestart()
{
/// dispose the application context
this.Dispose();
Application.Restart();
}
我必须在重新启动之前处理应用程序上下文,因为应用程序的新实例需要一些资源。然而,requestRestart()
可以从另一个线程调用所以我不能在ApplicationContext.Dispose()
方法中或直接在重新启动方法中处理appForm
,否则我会得到一个跨线程异常。
如果在用户单击调用appForm.Show()
的托盘图标时,表单在重新启动之前已显示,则会自动调用appForm.Dispose(true)
。根据MSDN:
如果使用Show方法显示表单,则会自动调用Dispose。
否则,如果表单从未显示,GC终结器将调用Dispose(false)
。
如何确保在重新启动之前处理此表单?
我建议您将appForm.Show()
从构造函数中删除,并将其放入从任务栏图标调用的方法中。
在您的托盘图标打开形式方法中,将appForm.Show()
包装在使用块中:
using (appForm = new AppForm()) {
appForm.Show();
}
这样,每当窗体关闭时,它就会自行处理。
此外,在requestRestart()
方法中放置以下内容:
appForm?.Close();
这将确保在上下文强制重新启动时关闭窗体。
如果你没有使用最新版本的.NET,下面的程序将实现同样的效果:
if (appForm != null)
appForm.Close();
编辑
这是一个完整的例子。这个答案对你如何处理背景任务有点固执己见,但我认为你会发现它非常有效。
解释被内联为注释。
在您的程序.cs:
private static void Main()
{
int restartCount = 0;
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
var applicationCtx = new MyApplicationContext();
applicationCtx.RestartRequested += (o, e) =>
{
restartCount++; //this is just here so my program would stop restarting
if (restartCount > 5) Application.Exit();
Application.Restart();
};
Application.Run(applicationCtx);
}
然后在MyApplicationContext.cs:中
internal class MyApplicationContext : ApplicationContext
{
private NotifyIcon notifyIcon;
private IContainer components;
private AppForm appForm;
public event EventHandler RestartRequested;
public MyApplicationContext()
{
notifyIcon = new NotifyIcon()
{
ContextMenuStrip = new ContextMenuStrip { Text = "Open Form" },
Text = "Application",
Visible = true,
Icon = new Icon("icon.ico")
};
appForm = new AppForm();
notifyIcon.DoubleClick += (o, e) =>
{
appForm.Show();
};
RestartRequested += (o, e) =>
{
appForm?.Close(); //Close() will dispose the form as well.
notifyIcon?.Dispose();
};
BackgroundWork();
}
private void BackgroundWork()
{
Task.Run<bool>(() => //Here we are telling Task to run a background operation and return a bool
{
//this body will run in a separate thread
Thread.Sleep(5000); //this represents your background work
var restart = true; //whatever result the bg work yields
return restart;
}).ContinueWith((task) => //task is an instance of Task from above containing the result fromm the background work
{
var shouldRestart = task.Result; // Result is the value you returned in the body Run body above
if (shouldRestart) RestartRequested?.Invoke(this, EventArgs.Empty);
},
TaskScheduler.FromCurrentSynchronizationContext()); //This will return on the UI thread now, no need to worry about thread boundaries
}
}