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VB中文件操作的两种方式

freebird — Sat, 15 Jul 2006 05:35:00 GMT

1.文本文�g的操�?br />

此种方式是以行�ؓ单位�q�行��d��的基本单位，主要应用的方法和函数有Open,Close,Line Input,FreeFile�Q�EOF�{�。下面先��q�其功能然后�l�合代码�C�Z��q�行说明�?/font>

Open�Q�顾名思义�Q�它的作用是打开文�g�Q�换而言之打开某个文�g��是获得某个的控制权�Q�一般情况下当文件处于打开状态时只有打开者才能对它进行操作。打开文�g时要指定一个整��C��为文件号�Q�以后的操作都是针对�q�个代号�q�行的，而不是针�Ҏ��件名。文件号也叫句柄�Q�在�E�序中一个文件号只能指向一个文�Ӟ��不能出现两个文�g同时��h��相同句柄的情��c�?/font>

Close:关闭文�g�Q�即释放文�g的控制权�?/font>

Line Input:以行为单位取得文件内容，以行为单位是指从当前位置开始到下一个换行符为止的内宏V��换行符是Chr(13) & Chr(10)两个字节�l�成�Q�VB中已定义了常量vbCrLf�Q�可直接使用。要注意的是Line Input��d��一行时会把行尾的换行符��L��Q�因此我们在��d��每行内容时要记得补上换行�W�才能保持得到的内容与文件一致�?/font>

FreeFile:得到�I�闲的文件号�Q�用�q�个函数取得文�g号可以避免文件号的冲�H��?/font>

例如�Q?br />

    Dim strFileName As String '文�g�?/span>
     Dim lngHandle As Long ' 文�g句柄
     Dim strAll As String ' 所��d��的文本文件的所有内�?/span>
     Dim strLine As String ' 在��@环中存放每行的内�?/span>

    strFileName = " c:\b.txt "
     ' 获得文�g的句�?/span>
    lngHandle = FreeFile()

     ' For后面的参数表�C�Z��何种方式打开文�g�Q�Input是读取，Output是覆盖写入，Append是追加写�?/span>
    Open strFileName For Input As lngHandle

     ' 循环直到文�g��?/span>
     Do While Not EOF(lngHandle)
         ' 每次��d��一行存攑֜�strLine变量�?/span>
        Line Input #lngHandle, strLine
         ' 每次��d��都把所��d��的内容连接到strAll变量�Q�由于Line Input��L��了换行符�Q�所以这里补�?/span>
        strAll = strAll & strLine & vbCrLf
     Loop

     ' 昄��得到的全部分内容
MsgBox strAll, vbInformation

    �Ҏ��本文件的写入相对��单些�Q�有三个步骤�Q�打开文�g�Q�写入文本，关闭文�g�?br />
代码�C�Z��Q?br />
     Dim strFileName As String ' 文�g�?/span>
     Dim lngHandle As Long ' 句柄
     Dim strWrite As String ' 要写入的文本内容

    strFileName = " c:\w.txt "
    lngHandle = FreeFile() ' 取得句柄

     ' 准备要写入的内容
    strWrite = " 落日楼头�Q�断鸿声里，江南游子。把吴钩看了�Q�栏�q�拍遍，无�h会、登临意�?/span> "
    Open strFileName For Output As lngHandle     ' 打开文�g
    Print #lngHandle, strWrite     ' 写入文本
    Close lngHandle     ' 关闭文�g
MsgBox " 写入完成�?/span> " , vbInformation

常用到的一个函敎ͼ�用来写日志用�Q?br />

Sub setLog(str As String )
' ---------
' 写日�?/span>
' ---------
Open App.Path & " \log\ " & CStr ( Date ) & " _log.txt " For Append As # 1
Write # 1 , str
Close # 1
End Sub

二进制文件的操作

所有文件的存储其实质都是二�q�制的，二进制文件往往�׃��部分�l�成�Q�一部分是文件头另一部分存放了文件的内容。文件头通常存放与文件格式有关的信息�Q�以BMP�{�图象文件�ؓ例，它们的文件头中存放了是何�U�图形格式、图象大��、调色板�{�信息，要显�C�图象时先读取文件头以获得文件的详细信息�Q�然后再按其格式把图象内�Ҏ��C�出来。用二进制方式可以操作�Q何的文�g�Q�当然至关重要的一�Ҏ��要清楚了解所操作文�g的文件头�l�构�?/font>

VB中二�q�制文�g操作主要应用的方法和函数有：Open,Close,Get,Put�{��?/font>

Open�Q�在For后面的打开模式要用Binary�?/font>

Close:关闭文�g�?/font>

Get:在指定位�|�取得文件的内容�Q�如果省略位�|�则从当前位�|�读取�?/font>

Put:在指定位�|�写入文�Ӟ��如果省略位置参数��׃��当前位置写�?/font>

下面�l�合代码讲解二进制文件的操作�?/font>

下述�E�序完成了将两个文�g�l�合成一个文件以及将�q�个�l�合后的文�g再拆分成原来的两个文件。文件头的结构是自己定义的，非常��单，�?个字节（也就是两个长整型的长度）�Q�前4个字节存攄��一个文件的长度�Q�后4个字节存攄��二个文�g的长度。�ؓ了更直观地表达文件的�l�构�Q�现假设有两个文�Ӟ��W�一个文仉��度是100字节�Q�第二个文�g�?00字节�Q�那么合�q�后得到的文件应该是308字节。按��序来看�Q�文件的�l�构是：

4�W�一文�g的长�?/font>

4�W�二文�g的长�?/font>

100�W�一文�g的二�q�制内容

200�W�二文�g的二�q�制内容

除了文�g头的8字节长度是固定的后面的长度都会因文�g的不同而变化的�?/font>

‘实现文件的合�ƈ

Private Sub MergeFile()

     Dim strFileName1 As String ' �W�一个文�?/span>
     Dim strFileName2 As String ' �W�二个文�?/span>
     Dim strOutput As String ' 合�ƈ后的文�g
     Dim aryContent() As Byte ' 用来��d��文�g的数�l�，每次��d��前要重定�?/span>

    strFileName1 = " c:\a.bmp "
    strFileName2 = " c:\b.bmp "
    strOutput = " c:\out.bmp "

     ' 注意下面三个Open语句都是用Binary模式打开�?/span>
    Open strOutput For Binary As # 100
    Open strFileName1 For Binary As # 1
    Open strFileName2 For Binary As # 2

    Put # 100 , , LOF( 1 ) ' 取得�W�一文�g的长度，�q�把它写入到合�ƈ文�g的文件头�?/span>
    Put # 100 , , LOF( 2 ) ' 取得�W�二文�g的长度，�q�写入到合�ƈ文�g的文件头�?/span>

     ReDim aryContent(LOF( 1 ) - 1 ) ' 重定义数�l�，��取文件做准备
     Get # 1 , , aryContent() ' 取得�W�一文�g的内容到数组

    Put # 100 , , aryContent() ' 把第一文�g的内容写到合�q�文件中

     ReDim aryContent(LOF( 2 ) - 1 )

     Get # 2 , , aryContent()
    Put # 100 , , aryContent()

     ' 关闭文�g
    Close # 1
    Close # 2
    Close # 100
End Sub

实现文�g的拆�?/font>

Private Sub SplitFile()

     Dim strFileName1 As String
     Dim strFileName2 As String
     Dim strFileSplit As String
     Dim aryContent() As Byte
     Dim lngLOF( 1 ) As Long ' 存放从文件头取得的两个文件的长度
    strFileName1 = " c:\a2.bmp "
    strFileName2 = " c:\b2.bmp "
    strFileSplit = " c:\out.bmp "

    Open strFileSplit For Binary As # 100

     Get # 100 , , lngLOF( 0 ) ' 取得�W�一文�g的长�?/span>
     Get # 100 , , lngLOF( 1 ) ' �W�二文�g的长�?/span>

    Open strFileName1 For Binary As # 1
    Open strFileName2 For Binary As # 2

     ReDim aryContent(lngLOF( 0 ) - 1 ) ' 用第一文�g的长度重定义数组�Q��ؓ��d��W�一文�g做准�?/span>
     Get # 100 , 9 , aryContent() ' 从第9字节�Q�即文�g后面开始读取第一文�g的内�?/span>
    Put # 1 , , aryContent() ' 把取得的内容写入到拆分文件中

     ReDim aryContent(lngLOF( 1 ) - 1 )

     Get # 100 , 9 + lngLOF( 0 ) + 1 , aryContent() ' 从第9字节再加上第一文�g的长度处开始读取第二文件的内容�Q�这里可以清楚地看到文�g头的作用�?/span>

    Put # 2 , , aryContent

    Close # 1
    Close # 2
    Close # 100
     MsgBox " 拆分完成�?/span> " , vbInformation

文本文�g�׃��没有格式所以它的读写都比较��单和直观�Q�而用二进制操作文件时其实质就是对文�g头的理解�Q�如果不知道文�g头的�l�构那就无法�Ҏ��件进行处理了�Q�知道了文�g头所包含的信息后�Q�对文�g的操作其实就是按规则�q�行Get、Put�|�了�?/font>

freebird 2006-07-15 13:35 发表评论

如何用CommonDialog实现只选择路径�Q��{载）

freebird — Mon, 03 Jul 2006 01:06:00 GMT

用CommonDialog实现只选择路径:

Private Declare Function SHBrowseForFolder Lib "shell32.dll" Alias "SHBrowseForFolderA" (LpBrowseInfo As BROWSEINFO) As Long
Private Declare Function SHGetPathFromIDlist Lib "shell32.dll" Alias "SHGetPathFromIDListA" (ByVal pidl As Long, ByVal pszPath As String) As Long
Private Type BROWSEINFO
  hOwner As Long
  pidlroot As Long
  pszDisplayName As String
  lpszTitle As String
  ulFlags As Long
  lpfn As Long
  lparam As Long
  iImage As Long
End Type
Public Function GetFolder(Optional Title As String, Optional hwnd) As String

    Dim bi As BROWSEINFO
    Dim pidl As Long
    Dim folder As String

folder = Space(255)

With bi
   If IsNumeric(hwnd) Then .hOwner = hwnd
   .ulFlags = BIF_RETURNONLYFSDIRS
   .pidlroot = 0
   If Title <> "" Then
      .lpszTitle = Title & Chr$(0)
   Else
      .lpszTitle = "选择目录" & Chr$(0)
    End If
End With

pidl = SHBrowseForFolder(bi)
If SHGetPathFromIDlist(ByVal pidl, ByVal folder) Then
    GetFolder = Left(folder, InStr(folder, Chr$(0)) - 1)
Else
    GetFolder = ""
End If
End Function
\'调用方式
\'FilePath=GetFolder("打开一个目�?, Form1.hwnd)

freebird 2006-07-03 09:06 发表评论

vb 实现查找�q�程

freebird — Wed, 28 Jun 2006 05:17:00 GMT

vb查找�q�程�Q�用到的API函数�?br />
Private Declare Function CreateToolhelp32Snapshot Lib "kernel32" (ByVal dwFlags As Long, ByVal th32ProcessID As Long) As Long

Private Declare Function Process32First Lib "kernel32" (ByVal hSnapshot As Long, lppe As PROCESSENTRY32) As Long

Private Declare Function Process32Next Lib "kernel32" (ByVal hSnapshot As Long, lppe As PROCESSENTRY32) As Long

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

Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Long, ByVal blnheritHandle As Long, ByVal dwAppProcessId As Long) As Long

Private Declare Function TerminateProcess Lib "kernel32" (ByVal ApphProcess As Long, ByVal uExitCode As Long) As Long

Private Type PROCESSENTRY32

dwSize As Long

cntUsage As Long

th32ProcessID As Long

th32DefaultHeapID As Long

th32ModuleID As Long

cntThreads As Long

th32ParentProcessID As Long

pcPriClassBase As Long

dwFlags As Long

szExeFile As String * 1024

End Type

Private Const TH32CS_SNAPHEAPLIST = &H1

Private Const TH32CS_SNAPPROCESS = &H2

Private Const TH32CS_SNAPTHREAD = &H4

Private Const TH32CS_SNAPMODULE = &H8

Private Const TH32CS_SNAPALL = (TH32CS_SNAPHEAPLIST Or TH32CS_SNAPPROCESS Or TH32CS_SNAPTHREAD Or TH32CS_SNAPMODULE)

Private Const TH32CS_INHERIT = &H80000000

Private Declare Function RegisterWindowMessage Lib "user32" Alias "RegisterWindowMessageA" (ByVal lpString As String) As Long
Private WM_TASKBARCREATED As Long

'**********************************************************************
'在查扑և��?br />'**********************************************************************
Private Function FindPro(jinchenming As String)
Dim my As PROCESSENTRY32
Dim l As Long
Dim l1 As Long
Dim mName As String

Dim I As Integer
l = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
If l Then
my.dwSize = 1060

If (Process32First(l, my)) Then '遍历开�?/font>

Do
I = InStr(1, my.szExeFile, Chr(0))

mName = LCase(Left(my.szExeFile, I - 1))

If mName = jinchenming Then

PID = my.th32ProcessID

pname = mName

Dim mProcID As Long

mProcID = OpenProcess(1&, -1&, PID)

MsgBox pname
'TerminateProcess mProcID, 0&

Exit Function
End If
Loop Until (Process32Next(l, my) < 1)
End If
l1 = CloseHandle(l)
End If
End Function

freebird 2006-06-28 13:17 发表评论