在 VB 編程中經(jīng)常需要和文件系統(tǒng)打交道，比如獲取硬盤的剩余空間、判斷文件夾或文件是否存在等。在VB 推出文件系統(tǒng)對象(File System Object)以前，完成這些功能需要調(diào)用 Windows API 函數(shù)或者使用一些比較復(fù)雜的過程來實(shí)現(xiàn)，使編程復(fù)雜、可靠性差又容易出錯。使用 Windows 提供的的文件系統(tǒng)對象，一切變得簡單多了。以下筆者舉出一些編程中比較常用的例子，以函數(shù)或過程的形式提供給大家，讀者可在編程中直接使用，也可以改進(jìn)后實(shí)現(xiàn)更為強(qiáng)大的功能。
要應(yīng)用 FSO 對象，須要引用一個名為 Scripting 的類型庫，方法是，執(zhí)行 VB6.0 的菜單項(xiàng)“工程/引用”，添加引用列表框中的“Microsoft Scripting Runtime”一項(xiàng)。然后我們在“對象瀏覽器”中就可以看到 Scripting 類型庫下的眾多對象及其方法、屬性。
1、判斷光驅(qū)的盤符：
Function GetCDROM() ' 返回光驅(qū)的盤符(字母)
Dim Fso As New FileSystemObject '創(chuàng)建 FSO 對象的一個實(shí)例
Dim FsoDrive As Drive, FsoDrives As Drives '定義驅(qū)動器、驅(qū)動器集合對象
Set FsoDrives = Fso.Drives
For Each FsoDrive In FsoDrives '遍歷所有可用的驅(qū)動器
If FsoDrive.DriveType = CDRom Then '如果驅(qū)動器的類型為 CDrom
GetCDROM = FsoDrive.DriveLetter '輸出其盤符
Else
GetCDROM = ""
End If
Next
Set Fso = Nothing
Set FsoDrive = Nothing
Set FsoDrives = Nothing
End Function
2、判斷文件、文件夾是否存在：
'返回布爾值:True 存在，F(xiàn)alse 不存在，filername 文件名
Function FileExist(filename As String)
Dim Fso As New FileSystemObject
If Fso.FileExists(filename) = True Then
FileExist = True
Else
FileExist = False
End If
Set Fso = Nothing
End Function
'返回布爾值:True 存在，F(xiàn)alse 不存在，foldername 文件夾
Function FolderExist(foldername As String)
Dim Fso As New FileSystemObject
If Fso.FolderExists(foldername) = True Then
FolderExist = True
Else
FolderExist = False
End If
Set Fso = Nothing
End Function
3、獲取驅(qū)動器參數(shù):
'返回磁盤總空間大小(單位：M)，Drive = 盤符 A ,C, D ...
Function AllSpace(Drive As String)
Dim Fso As New FileSystemObject, Drv As Drive
Set Drv = Fso.GetDrive(Drive) '得到 Drv 對象的實(shí)例
If Drv.IsReady Then '如果該驅(qū)動器存在(軟驅(qū)或光驅(qū)里有盤片，硬盤存取正常)
AllSpace = Format(Drv.TotalSize / (2 ^ 20), "0.00") '將字節(jié)轉(zhuǎn)換為兆
Else
AllSpace = 0
End If
Set Fso = Nothing
Set Drv = Nothing
End Function
'返回磁盤可用空間大小(單位：M)，Drive = 盤符 A ,C, D ...
Function FreeSpace(drive)
Dim Fso As New FileSystemObject, drv As drive
Set drv = Fso.GetDrive(drive)
If drv.IsReady Then
FreeSpace = Format(drv.FreeSpace / (2 ^ 20), "0.00")
End If
Set Fso = Nothing
Set Drv = Nothing
End Function
'獲取驅(qū)動器文件系統(tǒng)類型，Drive = 盤符 A ,C, D ...
Function FsType(Drive As String)
Dim Fso As New FileSystemObject, Drv As Drive
Set Drv = Fso.GetDrive(Drive)
If Drv.IsReady Then
FsType = Drv.FileSystem
Else
FsType = ""
End If
Set Fso = Nothing
Set Drv = Nothing
End Function
4，獲取系統(tǒng)文件夾路徑：
'返回 Windows 文件夾路徑
Function GetWindir()
Dim Fso As New FileSystemObject
GetWindir = Fso.GetSpecialFolder(WindowsFolder)
Set Fso = Nothing
End Function
'返回 Windows\System 文件夾路徑
Function GetWinSysdir()
Dim Fso As New FileSystemObject
GetWinSysdir = Fso.GetSpecialFolder(SystemFolder)
Set Fso = Nothing
End Function
5，綜合運(yùn)用：一個文件備份通用過程：
'Filename = 文件名，Drive = 驅(qū)動器，F(xiàn)older = 文件夾(一層)
Sub BackupFile(Filename As String, Drive As String, Folder As String)
Dim Fso As New FileSystemObject '創(chuàng)建 FSO 對象實(shí)例
Dim Dest_path As String, Counter As Long
Counter = 0
Do While Counter < 6 '如果驅(qū)動器沒準(zhǔn)備好，繼續(xù)檢測。共檢測 6 秒
Counter = Counter + 1
Call Waitfor(1) '間隔 1 秒
If Fso.Drives(Drive).IsReady = True Then
Exit Do
End If
Loop
If Fso.Drives(Drive).IsReady = False Then '6 秒后目標(biāo)盤仍未準(zhǔn)備就緒，退出
MsgBox " 目標(biāo)驅(qū)動器 " & Drive & " 沒有準(zhǔn)備好！ ", vbCritical
Exit Sub
End If
If Fso.GetDrive(Drive).FreeSpace < Fso.GetFile(Filename).Size Then
MsgBox "目標(biāo)驅(qū)動器空間太?。?, vbCritical '目標(biāo)驅(qū)動器空間不夠，退出
Exit Sub
End If
If Right(Drive, 1) <> ":" Then
Drive = Drive & ":"
End If
If Left(Folder, 1) <> "\" Then
Folder = "\" & Folder
End If
If Right(Folder, 1) <> "\" Then
Folder = Folder & "\"
End If
Dest_path = Drive & Folder
If Not Fso.FolderExists(Dest_path) Then '如果目標(biāo)文件夾不存在，創(chuàng)建之
Fso.CreateFolder Dest_path
End If
Fso.CopyFile Filename, Dest_path & Fso.GetFileName(Filename), True
'拷貝，直接覆蓋同名文件
MsgBox " 文件備份完畢。", vbOKOnly
Set Fso = Nothing
End Sub
Private Sub Waitfor(Delay As Single) '延時過程，Delay 單位約為 1 秒
Dim StartTime As Single
StartTime = Timer
Do Until (Timer - StartTime) > Delay
Loop
End Sub
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