Pausing Code to Wait Until a Shelled Process Is Finished in Access 95-2002

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标题：Pausing Code to Wait Until a Shelled Process Is Finished in Access 95-2002

作者: Attac Consulting Group



Here's how to shell to another program from Access, stop your code while the shelled process operates and then resume your code once the process is finished. To do this you use the api functions "WaitforSingleObject", and "OpenProcess" to launch a shelled process and wait for it to complete. Listed below is the code to use.

1. On the declarations page of your module, add the following functions: Private Declare Function OpenProcess Lib "kernel32.dll" (ByVal _

     dwAccess As Long, ByVal fInherit As Integer, ByVal hObject _

     As Long) As Long

Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal _

      hHandle As Long, ByVal dwMilliseconds As Long) As Long

Private Declare Function CloseHandle Lib "kernel32" (ByVal _

      hObject As Long) As Long



2. Try out this test function, which launches any app you want to and waits until it is finished to display a message box (Note an " _ " underscore means line continuation): Function LaunchApp32 (MYAppname As String) As Integer

On Error Resume Next

Const SYNCHRONIZE = 1048576

Const INFINITE = -1&

Dim ProcessID&

Dim ProcessHandle&

Dim Ret&



LaunchApp32=-1

ProcessID = Shell(MyAppName, vbNormalFocus)

   If ProcessID<>0 then

       ProcessHandle = OpenProcess(SYNCHRONIZE, True, ProcessID&)

       Ret = WaitForSingleObject(ProcessHandle, INFINITE)

       Ret = CloseHandle(ProcessHandle)

  

       MsgBox "This code waited to execute until " _

          & MyAppName & " Finished",64

   Else

        MsgBox "ERROR : Unable to start " & MyAppname

        LaunchApp32=0

   End If

End Function

3. It is important to note that your function must include the code to close the process handle after the shelled application is complete, otherwise you will have a memory leak until you shut down Windows.

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标题:在Access 95-2002中，如何使代码的执行时中断，并启动一个外部程序直至完成后，恢复中断。

作者: Attac顾问组织

    以下是如何从access启动另一个外部程序，使原来执行代码中断，直至这个外部程序完成后，恢复中断。完成这个功能我们可以"WaitforSingleObject"和"OpenProcess" API函数来启动这个外部程序直至完成。请参考下面列出代码。

1.在您模块的声明页中，加上以下声明和过程：





Private Declare Function OpenProcess Lib "kernel32.dll" (ByVal _

     dwAccess As Long, ByVal fInherit As Integer, ByVal hObject _

     As Long) As Long

Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal _

      hHandle As Long, ByVal dwMilliseconds As Long) As Long

Private Declare Function CloseHandle Lib "kernel32" (ByVal _

      hObject As Long) As Long

2.请试验下面这个测试过程，它可是实现任何您想启动的一个外部应用程序直至完成，才弹出一个提示框。（“_”表示续行。）

Function LaunchApp32 (MYAppname As String) As Integer

On Error Resume Next

Const SYNCHRONIZE = 1048576

Const INFINITE = -1&

Dim ProcessID&

Dim ProcessHandle&

Dim Ret&



LaunchApp32=-1

ProcessID = Shell(MyAppName, vbNormalFocus)

   If ProcessID<>0 then

       ProcessHandle = OpenProcess(SYNCHRONIZE, True, ProcessID&)

       Ret = WaitForSingleObject(ProcessHandle, INFINITE)

       Ret = CloseHandle(ProcessHandle)

  

       MsgBox "This code waited to execute until " _

          & MyAppName & " Finished",64

   Else

        MsgBox "ERROR : Unable to start " & MyAppname

        LaunchApp32=0

   End If

End Function







值得注意的一点是，当这个外部应用程序完成后，在你的过程中必需包含一段代码用以关闭这个进程的句柄。否则内存将会溢出(即:内存死区)直到你关闭窗口为止。[em01][em01][em01]

[此贴子已经被作者于2005-8-18 15:42:12编辑过]

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