Question

我的第一个表单是登录表单，当用户正确登录时，我隐藏登录表单并显示第二个表单。现在，我想从第二种形式关闭它，而不是隐藏登录表单。我以为我能够做到这一点，但不知怎的，我遇到了麻烦。

到目前为止，我确实喜欢这个。

我制作了我的FrmLogin实现的界面：

df.loc

接口：

 Public Class FrmLogin
        Implements ICloseLogin

FrmLogin实现界面：

Public Interface ICloseLogin
    Sub Close()
End Interface

现在我将FrmLogin（Me）传递给第二个表单构造函数：

Private Sub ICloseLogin_Close() Implements ICloseLogin.Close
        Me.Close()
    End Sub

第二种形式：

Private Sub ShowMainForm()
        Dim FrmMain As New FrmMainMDI(Me)
        FrmMain.IsMdiContainer = True
        FrmMain.StartPosition = FormStartPosition.CenterScreen
        FrmMain.Show()
        'Me.Hide() 'not anymore
    End Sub

当我调试时，当涉及到行：closeloginfform.Close（）我想只看到FrmLogin被关闭，但所有都以某种方式关闭。为什么呢？

有待进一步讨论：

Public Class FrmMainMDI

    Private closeloginfform As ICloseLogin

 Sub New(frmlogin As ICloseLogin)

        ' This call is required by the designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.
        closeloginfform = frmlogin
    End Sub

    Private Sub FrmMainMDI_Shown(sender As Object, e As EventArgs) Handles MyBase.Shown
        closeloginfform.Close()
    End Sub

模块程序：

  Imports DataAccessLayer
        Imports FormsUtils
        Imports BusinessLayer
        Imports System.Data.SqlClient
        Imports System.Configuration
        Imports System.Reflection
        Imports System.IO
        Imports Microsoft.WindowsAPICodePack.Dialogs
        Imports Probix

        Public Class FrmLogin

            Private Property Form As New FormUtils
            Private Property DB As New Procs
            Private Property _login As String
            Private Property _password As String

            Private Sub btnLogin_Click(sender As System.Object, e As System.EventArgs) Handles btnLogin.Click
                CheckAccess()
            End Sub


            Private Sub btnClose_Click(sender As System.Object, e As System.EventArgs) Handles btnClose.Click
                Me.Close()
            End Sub

            Private Sub FrmLogin_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
                Try

                    DB.OpenConn()
                    If DB.conn.State = ConnectionState.Open Then
                        Call Form.InitCombo(CboLogin, "SELECT * from tbLogin", DB.conn, "Login", "Login")
                        Call Form.InitCombo(CboLanguage, "SELECT * from tbLanguage where Active = 1", DB.conn, "Language", "Id")
                        Lang.name = DirectCast([Enum].Parse(GetType(Lang.LangShortcut), CboLanguage.GetItemText(CboLanguage.SelectedItem)), Lang.LangShortcut)
                    Else
                        Logger.LogIt(Modules.FrmLogin.ToString & ":  " & Methods.FrmLogin_Load.ToString, WriteMsg.Write(IssueCode.SqlServerConnectionError_pl), Application.StartupPath & "\log.txt", False)
                        Application.Exit()
                    End If

                Catch ex As Exception
                   Logger.LogIt(ex.tostring)

                    Application.Exit()
                Finally
                    DB.CloseConn()
                End Try
            End Sub

             Private Sub CheckAccess()
    Try
        _login = CboLogin.SelectedValue
        _password = txtPassword.Text
        If Not String.IsNullOrEmpty(txtPassword.Text) And Form.WybranoCombo(CboLogin, "Zaznacz login") Then
            Dim strcon = New AppSettingsReader().GetValue("ConnectionString", GetType(System.String)).ToString()
            Using con As New SqlConnection(strcon)
                Using cmd As New SqlCommand("Select COUNT(*) FROM tbLogin WHERE Login = @Login And Password = @Password", con)
                    cmd.CommandType = CommandType.Text
                    cmd.Parameters.AddWithValue("@Login", _login)
                    cmd.Parameters.AddWithValue("@Password", _password)
                    con.Open()
                    Dim o As Integer = cmd.ExecuteScalar()

                    '--CREDENTIALS OK
                    If o > 0 Then
                        CboLogin.Hide()
                        txtPassword.Hide()
                        btnLogin.Hide()
                        Label1.Hide()
                        Label2.Hide()
                        Try
                        Catch ex As Exception
                            MsgBox(ex.ToString)
                            End
                        End Try
                        '--CREDENTIALS NOT OK !!
                    Else
                        MsgBox("Wrong credentials")
                    End If

                End Using
            End Using
        Else
            MsgBox("Write some password !!")
        End If
    Catch ex As Exception
        Logger.LogIt(Modules.FrmLogin.ToString & ":" & Methods.FrmLogin_Load.ToString, WriteMsg.Write(IssueCode.Unknown_pl) & " ------> EX-MESSAGE: " & ex.ToString, Application.StartupPath & " \log.txt", False)
        Return
    End Try
End Sub

            Public Sub taskDialog_Opened(sender As Object, e As EventArgs)
                Dim taskDialog As TaskDialog = TryCast(sender, TaskDialog)
                taskDialog.Icon = taskDialog.Icon
                If Not taskDialog.FooterIcon = TaskDialogStandardIcon.None Then
                    taskDialog.FooterIcon = taskDialog.FooterIcon
                End If
                taskDialog.InstructionText = taskDialog.InstructionText
            End Sub

        End Class

进一步讨论2

解决了???：我在CheckAccess（）子行中添加了一行，这一行：

  Module Program
    Public Sub main()
        Application.EnableVisualStyles()

        Dim result As DialogResult
        Using frmL As New FrmLogin
            result = frmL.ShowDialog
        End Using

        If result = DialogResult.OK Then
            Dim FrmMainMDI As New FrmMainMDI()
            Application.Run(FrmMain)
        End If
    End Sub
End Module

所以代码的和平只是改变了：

Me.DialogResult = DialogResult.OK

Answer 1

执行此操作的一种较少涉及的方法是从Sub Main启动您的应用，并且只有在LogIn正确的情况下才启动应用。为此：

将模块添加到您的应用程序，并将其命名为Program。添加Public Sub Main
转到项目属性，然后取消选中Enable Application Framework
现在，对于Startup Object，请选择“Sub Main”

您实际上可以为模块命名，“程序”是描述性的，并且是C＃中使用的约定。然后是Sub Main代码：

Public Sub Main()

    Application.EnableVisualStyles()

    Dim result As DialogResult
    Using frmL As New frmLogin
        result = frmL.ShowDialog
    End Using

    If result = DialogResult.OK Then
        frmMain = New MainFrm()
        Application.Run(frmMain)
    End If

End Sub

现在，你的两个表格甚至不需要彼此了解。如果/当登录失败时，MainForm甚至不存在。与开始/加载MainForm相关的任何开销也会延迟，直到（并且除非）登录通过。

您的登录按钮将是这样的（取决于允许的失败尝试次数）：

Private Sub btnLogIn_Click(sender As Object, e As EventArgs) Handles btnLogIn.Click
    If IsValidUser(tbName.Text, tbPW.Text) Then
        DialogResult = Windows.Forms.DialogResult.OK
    Else
        If tries >= 3 Then
            DialogResult = Windows.Forms.DialogResult.Cancel
        Else
            tries += 1
            Exit Sub
        End If
    End If
    Me.Hide()
End Sub

从第二种形式关闭表格

1 个答案: