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Evento Application.ApplicationExit

 

Publicado: octubre de 2016

Se produce cuando la aplicación se va a cerrar.

Espacio de nombres:   System.Windows.Forms
Ensamblado:  System.Windows.Forms (en System.Windows.Forms.dll)

public static event EventHandler ApplicationExit

You must attach the event handlers to the M:System.Windows.Forms.Application.Exit event to perform unhandled, required tasks before the application stops running. You can close files opened by this application, or dispose of objects that garbage collection did not reclaim.

Because this is a static event, you must detach any event handlers attached to this event in the E:System.Windows.Forms.Application.ApplicationExit event handler itself. If you do not detach these handlers, they will remain attached to the event and continue to consume memory.

The following code example displays two forms and exits the application when both forms are closed. When the application starts and exits, the position of each form is remembered. This example demonstrates using the E:System.Windows.Forms.Application.ApplicationExit event to know when the form positions should be persisted to the file, and when the FileStream should be closed.

The class MyApplicationContext inherits from T:System.Windows.Forms.ApplicationContext and keeps track of when each form is closed, and exits the current thread when they both are. The class remembers the position of each form when it is closed. When the E:System.Windows.Forms.Application.ApplicationExit event occurs, the class writes the positions of each for the user to the file. The form position data is stored in a file titled appdata.txt that is created in the location determined by P:System.Windows.Forms.Application.UserAppDataPath. The Main method calls Application.Run(context) to start the application given the T:System.Windows.Forms.ApplicationContext.

This code is an excerpt from the example shown in the T:System.Windows.Forms.ApplicationContext class overview. See T:System.Windows.Forms.ApplicationContext for the whole code listing.

private MyApplicationContext() {
    formCount = 0;

    // Handle the ApplicationExit event to know when the application is exiting.
    Application.ApplicationExit += new EventHandler(this.OnApplicationExit);

    try {
        // Create a file that the application will store user specific data in.
        userData = new FileStream(Application.UserAppDataPath + "\\appdata.txt", FileMode.OpenOrCreate);

    } catch(IOException e) {
        // Inform the user that an error occurred.
        MessageBox.Show("An error occurred while attempting to show the application." + 
                        "The error is:" + e.ToString());

        // Exit the current thread instead of showing the windows.
        ExitThread();
    }

    // Create both application forms and handle the Closed event
    // to know when both forms are closed.
    form1 = new AppForm1();
    form1.Closed += new EventHandler(OnFormClosed);            
    form1.Closing += new CancelEventHandler(OnFormClosing);            
    formCount++;

    form2 = new AppForm2();
    form2.Closed += new EventHandler(OnFormClosed);            
    form2.Closing += new CancelEventHandler(OnFormClosing);            
    formCount++;

    // Get the form positions based upon the user specific data.
    if (ReadFormDataFromFile()) {
        // If the data was read from the file, set the form
        // positions manually.
        form1.StartPosition = FormStartPosition.Manual;
        form2.StartPosition = FormStartPosition.Manual;

        form1.Bounds = form1Position;
        form2.Bounds = form2Position;
    }

    // Show both forms.
    form1.Show();
    form2.Show();
}

private void OnApplicationExit(object sender, EventArgs e) {
    // When the application is exiting, write the application data to the
    // user file and close it.
    WriteFormDataToFile();

    try {
        // Ignore any errors that might occur while closing the file handle.
        userData.Close();
    } catch {}
}

.NET Framework
Disponible desde 1.1
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