VB:如何發送WM_KEYDOWN和WM_KEYUP訊息

其實沒什麼說的，只是最近一段時間問的人比較多，所以寫上幾句
簡單的說，有兩個需要注意的地方，一是要用postmessage發送訊息，二是這兩個訊息lparam參數比較複雜，發送訊息的時候要構造好lparam參數，下面給出範例程式碼：
Option Explicit
Private Declare Function MapVirtualKey Lib "user32" Alias "MapVirtualKeyA" (ByVal wCode As Long, ByVal wMapType As Long) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Const WM_KEYDOWN = &H100
Private Const WM_KEYUP = &H101
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Private Sub Command1_Click()
    Dim jsb As Long
    jsb = FindWindow("notepad", vbNullString)
    Dim mhwnd As Long
    mhwnd = FindWindowEx(jsb, 0, "edit", vbNullString)
    Dim lParam As Long
    lParam = makelparam(vbKey5, False)
    PostMessage mhwnd, WM_KEYDOWN, vbKey5, lParam
    lParam = makelparam(vbKey5, True)
    PostMessage mhwnd, WM_KEYUP, vbKey5, lParam
End Sub

Private Function makelparam(ByVal VirtualKey As Long, ByVal flag As Boolean) As Long
    Dim s As String
    Dim Firstbyte As String 'lparam參數的24-31位
    If flag = False Then 'keydown
        Firstbyte = "00"
    Else
        Firstbyte = "C0" 'keyup
    End If
    Dim Scancode As Long
    '獲得虛擬鍵掃描碼
    Scancode = MapVirtualKey(VirtualKey, 0)
    Dim Secondbyte As String 'lparam參數的16-23位，即虛擬鍵掃描碼
    Secondbyte = Right("00" & Hex(Scancode), 2)
    s = Firstbyte & Secondbyte & "0001" '0001為lparam參數的0-15位，即發送次數
    makelparam = Val("&H" & s)
End Function