vb.net使用FindWindowex在另一个应用程序中查找messagebox

发布时间：2020-12-17 07:20:52 所属栏目：百科来源：网络整理

导读：我有一个visual basic应用程序需要找到Microsoft Access,它有一个消息框,然后Send Enter到消息框. 我跟着这篇文章(FindWindow FindWindowEx). 它找到Access并将其带到前台,但它不想找到消息框并将其带到前面： Public Class Form1 Private Declare Function

我有一个visual basic应用程序需要找到Microsoft Access,它有一个消息框,然后Send Enter到消息框.

我跟着这篇文章(FindWindow FindWindowEx).

它找到Access并将其带到前台,但它不想找到消息框并将其带到前面：

enter image description here

Public Class Form1

 Private Declare Function SetForegroundWindow Lib "user32" (ByVal hwnd As IntPtr) As Long

 Private Declare Auto Function FindWindow Lib "user32.dll" ( _
 ByVal lpClassName As String,_
 ByVal lpWindowName As String _
 ) As IntPtr

 Private Declare Auto Function FindWindowEx Lib "user32.dll" ( _
 ByVal hwndParent As IntPtr,_
 ByVal hwndChildAfter As IntPtr,_
 ByVal lpszClass As String,_
 ByVal lpszWindow As String _
 ) As IntPtr

 Private Sub Form1_Load(sender As Object,e As EventArgs) Handles MyBase.Load
  Dim hWnd As IntPtr
  hWnd = FindWindow("OMain",Nothing)

  MsgBox(hWnd) 'FINDS 1640402

  Dim hWndChild1 As IntPtr = _
  FindWindowEx(hWnd,IntPtr.Zero,"#32770 (Dialog)","Microsoft Access")

  MsgBox(hWndChild1) 'FIRST PROBLEM IT FINDS ZERO HERE

  Dim hWndChild1Button As IntPtr = _
  FindWindowEx(hWndChild1,"Button","OK")

  MsgBox(hWndChild1Button) 'ALSO FINDS ZERO HERE

  If hWndChild1Button <> IntPtr.Zero Then
   SetForegroundWindow(hWndChild1Button)
   SendKeys.SendWait("{Enter}")
  End If

 End Sub
End Class

enter image description here

解决方法

代码未使用正确的winapi函数. FindWindowEx()可以找到子窗口,但MsgBox()显示的窗口不是子窗口.它是一个顶级窗口,您可以使用FindWindow()找到它.

但该功能不足以找到您要关闭的特定消息框.需要一种更好的方法,您可以使用的方法是使用EnumThreadWindows()枚举同一线程拥有的窗口.关于MsgBox()的好处是,由于对话框是模态的,因此只有一个这样的窗口.

SendKeys()也不够精确,如果消息框在前台,它只能正常工作.更好的方法是通过向BM_CLICK消息发送实际单击按钮.使用Access表单测试的代码：

Imports System.Runtime.InteropServices
Imports System.ComponentModel
Imports System.Text

Module Module1
    Sub Main()
        '' Find the MS-Access host window
        Dim access = FindWindow("OMain",Nothing)
        If access = IntPtr.Zero Then Throw New Win32Exception()
        '' Enumerate the windows owned by the same thread
        Dim pid As Integer
        Dim tid = GetWindowThreadProcessId(access,pid)
        If tid = 0 Then Throw New Win32Exception()
        EnumThreadWindows(tid,AddressOf ClickOkButton,Nothing)
    End Sub

    Private Function ClickOkButton(hWnd As IntPtr,lp As IntPtr) As Boolean
        '' Verify the class name is #32770
        Dim buf As New StringBuilder(256)
        GetClassName(hWnd,buf,256)
        If buf.ToString <> "#32770" Then Return True
        '' Find the OK button (control ID 2)
        Dim okbutton = GetDlgItem(hWnd,2)
        If okbutton = IntPtr.Zero Then Return True
        '' Activate the dialog,just in case
        SetActiveWindow(hWnd)
        '' Click the button
        SendMessage(okbutton,BM_CLICK,IntPtr.Zero)
        '' Done,no need to continue enumerating windows
        Return False
    End Function
End Module

Friend Module NativeMethods
    <DllImport("user32.dll",SetLastError:=True,CharSet:=CharSet.Auto)>
    Friend Function FindWindow(ByVal lpClassName As String,ByVal lpWindowName As String) As IntPtr
    End Function

    <DllImport("user32.dll",SetLastError:=True)>
    Friend Function GetWindowThreadProcessId(ByVal hwnd As IntPtr,ByRef lpdwProcessId As Integer) As Integer
    End Function

    Friend Delegate Function EnumThreadDelegate(hWnd As IntPtr,lParam As IntPtr) As Boolean

    <DllImport("user32.dll",SetLastError:=True)>
    Friend Function EnumThreadWindows(dwThreadId As Int32,lpfn As EnumThreadDelegate,lParam As IntPtr) As Boolean
    End Function

    <DllImport("user32.dll",CharSet:=CharSet.Auto)>
    Friend Function GetClassName(ByVal hWnd As System.IntPtr,ByVal lpClassName As System.Text.StringBuilder,ByVal nMaxCount As Integer) As Integer
    End Function

    <DllImport("user32.dll",CharSet:=CharSet.Auto)>
    Friend Function GetDlgItem(ByVal hDlg As IntPtr,id As Integer) As IntPtr
    End Function

    <DllImport("user32.dll",SetLastError:=True)>
    Friend Function SetActiveWindow(ByVal hWnd As IntPtr) As IntPtr
    End Function

    <DllImport("user32.dll")>
    Friend Function SendMessage(ByVal hWnd As IntPtr,ByVal msg As Integer,ByVal wp As IntPtr,ByVal lp As IntPtr) As IntPtr
    End Function

    Friend Const BM_CLICK As Integer = &HF5
End Module

通常的建议是favor UI Automation.

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!