获取cmd程序的输出结果(vb模块)
已有 10717 次阅读  2008-09-20 20:42  标签:  cmd  模块  程序  结果  输出 
cmd命令有很多具有强大的功能的，如果我们自己编码实现这些的功能，往往比较复杂。因此我们会想到在自己的程序通过调用这些命令以实现这些复杂的功能。比如修改目录的NTFS权限，如果通过自己编码来实现就很复杂，但是如果使用命令就很简单了。
如何获取到cmd命令执行的结果呢？网上有可以看到两种解决方案，一种是通过">>"管道操作符将输出数据写入文件，然后通过读取文件获取命令执行结果（实现简单，但时效性较差）。第二种是通过管道实现的（实现复杂，但时效性强）。
下面是第二种方案的实现（大部分是老外写的，我略作修改，放到一个VB模块中，方便使用）：
Option Explicit
Public Declare Function CreateProcess Lib "kernel32" Alias "CreateProcessA" _
(ByVal lpApplicationName As String, _
ByVal lpCommandLine As String, _
lpProcessAttributes As SECURITY_ATTRIBUTES, _
lpThreadAttributes As SECURITY_ATTRIBUTES, _
ByVal bInheritHandles As Long, _
ByVal dwCreationFlags As Long, _
lpEnvironment As Any, _
ByVal lpCurrentDirectory As String, _
lpStartupInfo As STARTUPINFO, _
lpProcessInformation As PROCESS_INFORMATION) As Long
Public Declare Function CloseHandle Lib "kernel32.dll" (ByVal hObject As Long) As Long
Public Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, _
lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, _
lpOverlapped As Long) As Long
Public Declare Function WaitForSingleObject Lib "kernel32" _
(ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
Public Declare Function CreatePipe Lib "kernel32" (phReadPipe As Long, _
phWritePipe As Long, lpPipeAttributes As SECURITY_ATTRIBUTES, _
ByVal nSize As Long) As Long
Public Type STARTUPINFOstartupinfo
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
Public Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessId As Long
dwThreadId As Long
End Type
Public Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type
Public Const NORMAL_PRIORITY_CLASS As Long = &H20&
Public Const STARTF_USESTDHANDLES As Long = &H100&
Public Const STARTF_USESHO
WWINDOW As Long = &H1&
Public Const SW_HIDE As Long = 0&
Public Const INFINITE As Long = &HFFFF&
Public Function RunCommand(commandline As String) As String
Dim si As STARTUPINFO 'used to send info the CreateProcess
Dim pi As PROCESS_INFORMATION 'used to receive info about the created process
Dim retval As Long 'return value
Dim hRead As Long 'the handle to the read end of the pipe
Dim hWrite As Long 'the handle to the write end of the pipe
Dim sBuffer(0 To 63) As Byte 'the buffer to store data as we read it from the pipe
Dim lgSize As Long 'returned number of bytes read by readfile
Dim sa As SECURITY_ATTRIBUTES
Dim strResult As String 'returned results of the command line
'set up security attributes structure
With sa
.
nLength = Len(sa)
.bInheritHandle = 1& 'inherit, needed for this to work
.lpSecurityDescriptor = 0&
End With
'create our anonymous pipe an check for success
' note we use the default buffer size
' this could cause problems if the process tries to write more than this buffer size
retval = CreatePipe(hRead, hWrite, sa, 0&)
If retval = 0 Then
MsgBox "错误提示：创建管道失败!"
RunCommand = ""
Exit Function
End If
'set up startup info
With si
.cb = Len(si)
.dwFlags = STARTF_USESTDHANDLES Or STARTF_USESHOWWINDOW 'tell it to use (not ignore) the values below
.wShowWindow = SW_HIDE
.hStdOutput = hWrite 'pass the write end of the pipe as the processes standard output
End With
'run the command line and check for success
retval = CreateProcess(vbNullString, _
commandline & vbNullChar, _
sa, _
sa, _
1&, _
NORMAL_PRIORITY_CLASS, _
ByVal 0&, _
vbNullString, _
si, _
pi)
If retval Then
'wait until the command line finishes
' trouble if the app doesn't end, or waits for user input, etc
WaitForSingleObject pi.hProcess, INFINITE
'read from the pipe until there's no more (bytes actually read is less than what we told it to)
Do While ReadFile(hRead, sBuffer(0), 64, lgSize, ByVal 0&)
'convert byte array to string and append to our result
strResult = strResult & StrConv(sBuffer(), vbUnicode)
'TODO = what's in the tail end of the byte array when lgSize is less than 64???
Erase sBuffer()
If lgSize <> 64 Then Exit Do
DoEvents
Loop
'close the handles of the process
CloseHandle pi.hProcess
CloseHandle pi.hThread
Else
MsgBox "错误提示：创建进程失败!" & vbCrLf
End If
'close pipe handles
CloseHandle hRead
CloseHandle hWrite
'return the
command line output
RunCommand = Replace(strResult, vbNullChar, "")
End Function

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