vb.net 使用 FindWindowex 在另一个应用程序中查找消息框

Question

我有一个可视化基本应用程序，它需要找到具有消息框的 Microsoft Access，然后将 Enter 发送到消息框。

我关注了这篇文章( FindWindow FindWindowEx )。

它找到 Access 并将其置于前台，但它不想找到消息框并将其置于前台:

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, IntPtr.Zero, "Button", "OK")

  MsgBox(hWndChild1Button) 'ALSO FINDS ZERO HERE

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

 End Sub
End Class

Answer 1

该代码未使用正确的 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() 找到的那种。

但该功能不足以定位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() 枚举由同一线程拥有的窗口。 MsgBox() 的好处是只有一个这样的窗口，因为对话框是模态的。

SendKeys() 也不够好，它只有在消息框在前台时才能正常工作。更好的方法是通过向按钮发送 BM_CLICK 消息来实际单击按钮。测试代码，使用访问表单:

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, 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", SetLastError:=True, 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

通常的建议是到 favor UI Automation .