Question

是否可以在VB6中生成同步进程（即调用外部.exe），等待它终止，并获取返回值？

我们有遗留代码（显然在VB6中）我们需要调用.NET应用程序来执行一些复杂的任务，并且基于.NET应用程序的返回值，要么继续要么失败。有没有更好的方法来做这样的事情？

Answer 1

你的第一个选择应该是公开一个接口，将.NET接口暴露给COM并使用它（它更干净），但是如果由于某种原因你必须通过一个衍生过程来完成它使用这个VB6代码。

 Private Type STARTUPINFO
      cb As Long
      lpReserved As String
      lpDesktop As String
      lpTitle As String
      dwX As Long
      dwY As Long
      dwXSize As Long
      dwYSize As Long
      dwXCountChars As Long
      dwYCountChars As Long
      dwFillAttribute As Long
      dwFlags As Long
      wShowWindow As Integer
      cbReserved2 As Integer
      lpReserved2 As Long
      hStdInput As Long
      hStdOutput As Long
      hStdError As Long
   End Type

   Private Type PROCESS_INFORMATION
      hProcess As Long
      hThread As Long
      dwProcessID As Long
      dwThreadID As Long
   End Type

   Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
   Private Declare Function CreateProcessA Lib "kernel32" (ByVal lpApplicationName As Long, ByVal lpCommandLine As String, ByVal lpProcessAttributes As Long, ByVal lpThreadAttributes As Long, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, ByVal lpEnvironment As Long, ByVal lpCurrentDirectory As Long, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
   Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
   Private Declare Function GetExitCodeProcess Lib "kernel32" (ByVal hProcess As Long, lpExitCode As Long) As Long

   Private Const NORMAL_PRIORITY_CLASS = &H20&
   Private Const INFINITE = -1&
   Private Const SW_HIDE = 0
   Private Const SW_SHOWMINNOACTIVE = 7

   Public Function ExecCmd(cmdline As String, workdir As String) As Integer
      Dim proc As PROCESS_INFORMATION
      Dim start As STARTUPINFO
      Dim ret as Long

        ChDrive Left(workdir, 1) & ":"
        ChDir workdir

        start.cb = Len(start)
        start.wShowWindow = SW_SHOWMINNOACTIVE

        Call CreateProcessA(0&, cmdline, 0&, 0&, 1&, NORMAL_PRIORITY_CLASS, 0&, 0&, start, proc)
        Call WaitForSingleObject(proc.hProcess, INFINITE)
        Call GetExitCodeProcess(proc.hProcess, ret)
        Call CloseHandle(proc.hThread)
        Call CloseHandle(proc.hProcess)
        ExecCmd=ret
   End Function

Answer 2

' References: "Windows Script Host Shell Object Model" '
Function ExecuteCommand(cmd As String, ExpectedResult as Long) As Boolean
  Dim shell As New IWshRuntimeLibrary.WshShell
  Dim Result As Long

  Result = shell.Run(Command:=cmd, WindowStyle:=WshHide, WaitOnReturn:=True)

  ExecuteCommand = (Result = ExpectedResult)
End Function

Answer 3

您可以使用：

Option Explicit

Private Const INFINITE = &HFFFF&
Private Const SYNCHRONIZE = &H100000
Private Const PROCESS_QUERY_INFORMATION = &H400&

Private Declare Function CloseHandle Lib "kernel32" ( _
    ByVal hObject As Long) As Long

Private Declare Function GetExitCodeProcess Lib "kernel32" ( _
    ByVal hProcess As Long, _
    lpExitCode As Long) As Long

Private Declare Function OpenProcess Lib "kernel32" ( _
    ByVal dwDesiredAccess As Long, _
    ByVal bInheritHandle As Long, _
    ByVal dwProcessId As Long) As Long

Private Declare Function WaitForSingleObject Lib "kernel32" ( _
    ByVal hHandle As Long, _
    ByVal dwMilliseconds As Long) As Long

Private Function SyncShell( _
    ByVal PathName As String, _
    ByVal WindowStyle As VbAppWinStyle) As Long
    'Shell and wait.  Return exit code result, raise an
    'exception on any error.
    Dim lngPid As Long
    Dim lngHandle As Long
    Dim lngExitCode As Long

    lngPid = Shell(PathName, WindowStyle)
    If lngPid <> 0 Then
        lngHandle = OpenProcess(SYNCHRONIZE _
                             Or PROCESS_QUERY_INFORMATION, 0, lngPid)
        If lngHandle <> 0 Then
            WaitForSingleObject lngHandle, INFINITE
            If GetExitCodeProcess(lngHandle, lngExitCode) <> 0 Then
                SyncShell = lngExitCode
                CloseHandle lngHandle
            Else
                CloseHandle lngHandle
                Err.Raise &H8004AA00, "SyncShell", _
                          "Failed to retrieve exit code, error " _
                        & CStr(Err.LastDllError)
            End If
        Else
            Err.Raise &H8004AA01, "SyncShell", _
                      "Failed to open child process"
        End If
    Else
        Err.Raise &H8004AA02, "SyncShell", _
                  "Failed to Shell child process"
    End If
End Function

我可以在VB6中生成同步进程并检索其返回值吗？

3 个答案: