.net中简单而实用的类

01.Namespace My  02.    '右击解决方案的属性时，在“Application(应用)”中，单击“View  Application Events”便自动产生一个新的ApplicationEvents.vb。在此   03.    '里面共有五个事件。   04.  05.    '这是特别的类，几乎被很多开发者忽略，但是功能最简单，却是却实用的类，   06.    ' The following events are available for MyApplication:   07.    '    08.    ' Startup: Raised when the application starts, before the startup form is created.   09.    ' Shutdown: Raised after all application forms are closed.  This event is not raised if the application terminates abnormally.   10.    ' UnhandledException: Raised if the application encounters an unhandled exception.   11.    ' StartupNextInstance: Raised when launching a single-instance application and the application is already active.    12.    ' NetworkAvailabilityChanged: Raised when the network connection is connected or disconnected.   13.    Partial Friend Class MyApplication  14.        '检测计算是否接入网络   15.        Private Sub MyApplication_NetworkAvailabilityChanged(sender As Object, e As Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs) Handles Me.NetworkAvailabilityChanged  16.            SetConnectionStatus(e.IsNetworkAvailable)  17.        End Sub  18.  19.        '当应用程序各个窗体都关闭了。这个程序才运行，也是最后运行的程序   20.        Private Sub MyApplication_Shutdown(sender As Object, e As System.EventArgs) Handles Me.Shutdown  21.            MsgBox("程序已经关闭运行！")  22.        End Sub  23.  24.        '当应用程序最开始启动时就运行了。早于任何窗体，在这个地方来初始化变量是最好的   25.        Private Sub MyApp_Startup(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.StartupEventArgs) Handles Me.Startup  26.            ' When the application starts, set the connection status on the status strip   27.            MsgBox("程序将要开始启动")  28.  29.        End Sub  30.  31.        Public Sub SetConnectionStatus(ByVal connected As Boolean)  32.            'With My.Forms.MainForm.ConnectedStatusLabel   33.            '    If (connected) Then   34.            '        .Image = My.Resources.connected.ToBitmap   35.            '        .Text = My.Resources.ConnectedText   36.            '    Else   37.            '        .Image = My.Resources.disconnected.ToBitmap   38.            '        .Text = My.Resources.DisconnectedText   39.            '    End If   40.            'End With   41.        End Sub  42.  43.        Private Sub MyApplication_StartupNextInstance(sender As Object, e As Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs) Handles Me.StartupNextInstance  44.            MsgBox("程序已经启动一次了")  45.        End Sub  46.  47.        '当程序在运行中出错，而未作处理时，它是来收集错误并提示错误内容   48.        Private Sub MyApplication_UnhandledException(sender As Object, e As Microsoft.VisualBasic.ApplicationServices.UnhandledExceptionEventArgs) Handles Me.UnhandledException  49.            MsgBox("程序在运行中出现错误")  50.        End Sub  51.    End Class  52.  53.  54.End Namespace