VB动态调用外部API函数的方法

现在还是人类 2008-09-28 03:58:28

加精

这么久了都没放出过什么比较好的程序出来，让大家失望了。前段时间无聊搞了个类，今天拿出来和大家分享一下
主要是实现在VB中动态调用API函数的类，才疏学浅，见笑了。



'******************************************************************************** 

' 

'Name.......... APIClass 

'File.......... APIClass.cls 

'Version....... 1.0.0 

'Dependencies.. kernel32.DLL 

'Author........ Zhou Wen Xing<humanhome@126.com> 

'Date.......... Apr, 17nd 2008 

'UpdateURL..... http://bbs.rljy.com/?m=vbAPIClass 

' 

'Copyright (c) 2008 by www.rljy.com 

'Liuzhou city, China 

' 

'******************************************************************************** 

Option Explicit 

'============================================================================== 

'数据类型定义 

'============================================================================== 

Private Type VariableBuffer 

   VariableParameter() As Byte 

End Type 

'============================================================================== 

'API 函数声明 

'============================================================================== 

Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long 

Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Long, ByVal lpProcName As String) As Long 

Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long 

Private Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As Long) As Long 

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (lpDest As Any, lpSource As Any, ByVal cBytes As Long) 

'============================================================================== 

'成员定义 

'============================================================================== 

'类中的全局变量 

Private m_opIndex As Long 

Private m_OpCode() As Byte 

'******************************************************************************** 

'**   作    者 ：    人类(Supermanking) 

'**   函 数 名 ：    ExecuteAPI 

'**   输    入 ：    LIBPath(String)         -  刷新的目标窗口句柄，可为0 

'**            ：    APIScript(String)       -  场景图像的宽度 

'**   返    回 ：    (Long)                  -  返回零表示失败，非零表示成功 

'**   功能描述 ：    动态执行类库里的API函数 

'**   创建日期 ：    2008-04-17 

'**   修 改 人 ： 

'**   修改日期 ： 

'**   版    本 ：    Version 1.0.0 

'******************************************************************************** 

Public Function ExecuteAPI(LIBPath As String, APIScript As String) As Long 

   Dim hProcAddress As Long, hModule As Long, x As Long, y As Long 

   Dim RetLong As Long, FunctionName As String, FunctionParameter As String 

   Dim LongCount As Long, StringInfo As String, StrByteArray() As VariableBuffer 

   Dim StringSize As Long, ByteArray() As Byte, IsHaveParameter As Boolean 

   Dim ParameterArray() As String, OutputArray() As Long 

   StringSize = 0 

   ReDim StrByteArray(StringSize) 

   '识别函数名称 

   RetLong = InStr(1, APIScript, " ", vbTextCompare) 

   If RetLong = 0 Then 

      '没有参数的函数 

      FunctionName = APIScript 

      IsHaveParameter = False 

   Else 

      '带参数的函数 

      FunctionName = Left(APIScript, RetLong - 1) 

      IsHaveParameter = True 

       

      '识别函数参数 

      FunctionParameter = Right(APIScript, Len(APIScript) - RetLong) 

    

      '分析函数参数 

      ParameterArray = Split(FunctionParameter, ",") 

    

      '初始化函数内存大小 

      ReDim OutputArray(UBound(ParameterArray)) 

    

      '格式化函数参数 

      For x = 0 To UBound(ParameterArray) 

         If IsNumeric(Trim(ParameterArray(x))) = True Then 

            LongCount = CLng(Trim(ParameterArray(x))) 

            OutputArray(x) = LongCount 

         Else 

            StringInfo = Mid(Trim(ParameterArray(x)), 2, Len(ParameterArray(x)) - 3) 

            If Len(StringInfo) = 0 Then 

               OutputArray(x) = CLng(VarPtr(Null)) 

            Else 

               ReDim Preserve StrByteArray(StringSize) 

               ByteArray = StrConv(StringInfo, vbFromUnicode) 

               ReDim Preserve StrByteArray(StringSize).VariableParameter(UBound(ByteArray) + 1) 

               CopyMemory StrByteArray(StringSize).VariableParameter(0), ByteArray(0), UBound(ByteArray) + 1 

               OutputArray(x) = CLng(VarPtr(StrByteArray(StringSize).VariableParameter(0))) 

               StringSize = StringSize + 1 

            End If 

         End If 

      Next x 

      ReDim m_OpCode(400 + 6 * UBound(OutputArray)) '保留用来写m_OpCode 

   End If 

    

   '读取API库 

   hModule = LoadLibrary(ByVal LIBPath) 

   If hModule = 0 Then 

       ExecuteAPI = 0   'Library 读取失败 

       Exit Function 

   End If 



   '取得函数地址 

   hProcAddress = GetProcAddress(hModule, ByVal FunctionName) 

   If hProcAddress = 0 Then 

      ExecuteAPI = 0   '函数读取失败 

      FreeLibrary hModule 

      Exit Function 

   End If 

    

   If IsHaveParameter = True Then 

      '带参数的情况在此执行 

      ExecuteAPI = CallWindowProc(GetCodeStart(hProcAddress, OutputArray), 0, 1, 2, 3) 

   Else 

      '不带参数的情况在此执行 

      ExecuteAPI = CallWindowProc(hProcAddress, 0, 1, 2, 3) 

   End If 

    

   '释放库空间 

   FreeLibrary hModule 

End Function 



Private Function GetCodeStart(ByVal lngProc As Long, arrParams() As Long) As Long 

    Dim lngIndex As Long, lngCodeStart As Long 

    lngCodeStart = (VarPtr(m_OpCode(0)) Or &HF) + 1 

    m_opIndex = lngCodeStart - VarPtr(m_OpCode(0)) 

    For lngIndex = 0 To m_opIndex - 1 

        m_OpCode(lngIndex) =  

    Next lngIndex 

    For lngIndex = UBound(arrParams) To 0 Step -1 

       AddByteToCode  

       AddLongToCode arrParams(lngIndex) 

    Next lngIndex 

    AddByteToCode  

    AddLongToCode lngProc - VarPtr(m_OpCode(m_opIndex)) - 4 

    AddByteToCode  

    AddByteToCode  

    AddByteToCode  

    GetCodeStart = lngCodeStart 

End Function 



Private Sub AddLongToCode(lData As Long) 

    CopyMemory m_OpCode(m_opIndex), lData, 4 

    m_opIndex = m_opIndex + 4 

End Sub 



Private Sub AddIntToCode(iData As Integer) 

    CopyMemory m_OpCode(m_opIndex), iData, 2 

    m_opIndex = m_opIndex + 2 

End Sub 



Private Sub AddByteToCode(bData As Byte) 

    m_OpCode(m_opIndex) = bData 

    m_opIndex = m_opIndex + 1 

End Sub

使用方法也很简单，我举个例子：



Private Sub Command1_Click() 

   Dim API As New APIClass 

   Dim APIScript As String 

   '最简单的调用API函数 

   APIScript = "MessageBoxA 0, ""这是动态调用API函数显示的MSGBOX内容，下面将要在作面画一笔。"", ""API信息提示"", 0" 

   API.ExecuteAPI "C:\WINDOWS\system32\user32.dll", APIScript 

    

   '=============在作面画画============ 

   Dim DesktophWnd As Long, DesktophDC As Long 

   '取得桌面窗口句柄 

   DesktophWnd = API.ExecuteAPI("C:\WINDOWS\system32\user32.dll", "GetDesktopWindow") 

   '取得桌面窗口设备句柄 

   DesktophDC = API.ExecuteAPI("C:\WINDOWS\system32\user32.dll", "GetWindowDC " & DesktophWnd) 

   '在作面设备上画一条线 

   API.ExecuteAPI "C:\WINDOWS\system32\gdi32.dll", "LineTo " & DesktophDC & "," & Screen.Width / 15 & "," & Screen.Height / 15 

End Sub