vb.net 获取活动窗口的标题
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Get the title of the active window
提问by Max
I have declared the following WinAPI calls
我已经声明了以下 WinAPI 调用
<DllImport("USER32.DLL", EntryPoint:="GetActiveWindow", SetLastError:=True,
CharSet:=CharSet.Unicode, ExactSpelling:=True,
CallingConvention:=CallingConvention.StdCall)>
Public Shared Function GetActiveWindowHandle() As System.IntPtr
End Function
<DllImport("USER32.DLL", EntryPoint:="GetWindowText", SetLastError:=True,
CharSet:=CharSet.Unicode, ExactSpelling:=True,
CallingConvention:=CallingConvention.StdCall)>
Public Shared Function GetActiveWindowText(ByVal hWnd As System.IntPtr, _
ByVal lpString As System.Text.StringBuilder, _
ByVal cch As Integer) As Integer
End Function
Then, I call this subroutine to get the text in the active window's title bar
然后，我调用这个子程序来获取活动窗口标题栏中的文本
Public Sub Test()
Dim caption As New System.Text.StringBuilder(256)
Dim hWnd As IntPtr = GetActiveWindowHandle()
GetActiveWindowText(hWnd, caption, caption.Capacity)
MsgBox(caption.ToString)
End Sub
Finally, I get the following error
最后，我收到以下错误
Unable to find an entry point named 'GetWindowText' in DLL 'USER32.DLL'
无法在 DLL 'USER32.DLL' 中找到名为 'GetWindowText' 的入口点
How can I fix this issue?
我该如何解决这个问题？
回答by Hans Passant
<DllImport("USER32.DLL", EntryPoint:="GetWindowText", SetLastError:=True,
CharSet:=CharSet.Unicode, ExactSpelling:=True,
You insisted on ExactSpelling. Which is the problem, there are twoversions of GetWindowText exported by user32.dll. GetWindowTextA and GetWindowTextW. The A version uses an ansi string, a legacy string format with 8-bit characters encoded in the default code page that was last used in Windows ME. The W version uses a Unicode string, encoded in utf-16, the native Windows string type. The pinvoke marshaller will try either of them, based on the CharSet but you stopped it from doing so by using ExactSpelling := True. So it cannot find GetWindowText, it doesn't exist.
您坚持使用 ExactSpelling。这是哪个问题，user32.dll导出的GetWindowText有两个版本。GetWindowTextA 和 GetWindowTextW。A 版本使用 ansi 字符串，这是一种旧的字符串格式，其 8 位字符编码在 Windows ME 上次使用的默认代码页中。W 版本使用 Unicode 字符串，以 utf-16 编码，Windows 原生字符串类型。pinvoke 编组器将根据 CharSet 尝试其中的任何一个，但您使用 ExactSpelling := True 阻止了它这样做。所以它找不到GetWindowText，它不存在。
Either use EntryPoint := "GetWindowTextW" or drop ExactSpelling.
使用 EntryPoint := "GetWindowTextW" 或删除 ExactSpelling。
