VB随机访问数据文件:关闭 [英] VB Random Access data file: close

问题描述

我的某些RA数据文件保持挂起状态打开".我还找不到这是怎么回事，我也不知道文件号是什么

有没有一种方法可以使用My.Computer.FileSystem方法关闭"文件?

Some of my RA datafiles remain hung "open". I have not been able to find how this is happening yet and I don''t know what the file number is

Is there a way to absolutley "close" a file using a My.Computer.FileSystem method?

Is there a way to determine what the file number is for a given data file?

推荐答案

您能解释一下如何创建随机访问文件吗?
是通过VB6-FileGet和FilePut等实现的.您引用的FileNumbers表示您正在使用VB6和FreeFile.

我可以建议您使用NET并使用标准FileStream方法吗?然后，您可以开发一个可以创建不同字段的类.

Can you explain how you are creating a random access file?
Is it via VB6 - FileGet and FilePut etc. You refer to FileNumbers which suggests you are using VB6 and FreeFile.

Can I suggest you use NET and use standard FileStream methods. You can then develop a class that then creates the different fields.

尝试一下

Imports System.Text

   Public Function FnLStr(ByVal a As String, ByVal i As Integer, Optional ByVal s As Integer = 32) As String
      If a Is Nothing Then a = ""
      Return a.PadRight(i, Chr(s))
   End Function

   Public Function Encode(ByVal bt() As Byte, ByVal bg As Integer, ByVal s As String, ByVal len As Integer) As Byte()
      s = FnLStr(s, len)
      Dim unicode As Encoding = Encoding.Unicode
      Dim b() As Byte = unicode.GetBytes(s)
      For i = 0 To len * 2 - 1
         bt(bg + i) = b(i)
      Next
      Return bt
   End Function

   Public Function Decode(ByVal bt() As Byte, ByVal bg As Integer, ByVal len As Integer) As String
      Dim ea As Encoding = Encoding.ASCII
      Dim eu As Encoding = Encoding.Unicode
      Dim b(len * 2 - 1) As Byte
      For i = 0 To len * 2 - 1
         b(i) = bt(i + bg)
      Next
      b = Encoding.Convert(eu, ea, b)
      For i = 0 To UBound(b)
         If b(i) = 0 Then b(i) = 32
      Next
      Dim a(ea.GetCharCount(b, 0, b.Length) - 1) As Char
      ea.GetChars(b, 0, b.Length, a, 0)
      Return New String(a).Trim
   End Function

如您所见，您需要两倍的字符来存储Unicode

as you can see, you need twice as many characters to store Unicode

这是一个典型的类:-

Here is a typical class:-

Public Class MyClass
 Private bt(1234) As Byte
#Region " Properties "
   Public Property Bytes() As Byte()
      Get
         Return bt
      End Get
      Set(ByVal value As Byte())
         bt = value
      End Set
   End Property
   Public Property Access() As Integer
      Get
         Return bt(0)
      End Get
      Set(ByVal Value As Integer)
         bt(0) = CByte(Value)
      End Set
   End Property
   Public Property ChargeExpenses() As Byte
      Get
         Return bt(1)
      End Get
      Set(ByVal value As Byte)
         bt(1) = value
      End Set
   End Property
   Public Property ChargeExpensesValue() As Integer
      Get
         Return bt(2) + bt(3) * cn256
      End Get
      Set(ByVal value As Integer)
         bt(3) = CByte(value \ cn256)
         bt(2) = CByte(value - bt(3) * cn256)
      End Set
   End Property
   Public Property ChargeVat() As Boolean
      Get
         Return bt(7) = 1
      End Get
      Set(ByVal value As Boolean)
         If value Then bt(7) = 1 Else bt(7) = 0
      End Set
   End Property
   Public Property Cost() As Double
      Get
         Return FnBytesToReal(bt, 8) ' my own conversion function
      End Get
      Set(ByVal Value As Double)
         bt = FnRealToBytes(bt, 8, Value)
      End Set
   End Property
   Public Property Created() As String
      Get
         Dim a As String
         Try
            a = New Date(bt(20) + l_Times.BaseYear, bt(19), bt(18)).ToShortDateString
         Catch ex As Exception
            Try
               a = New Date(bt(18) + l_Times.BaseYear, bt(19), bt(20)).ToShortDateString
            Catch ex1 As Exception
               a = ""
            End Try
            a = ""
         End Try
         If a = "" Then Return CStr(Today) Else Return a
      End Get
      Set(ByVal Value As String)
         Dim v As Date = CDate(Value)
         bt(18) = CByte(v.Day)
         bt(19) = CByte(v.Month)
         bt(20) = CByte(v.Year - l_Times.BaseYear)
      End Set
   End Property
    Public Property Description(ByVal Index As Integer) As String
      Get
         Dim k As Integer
         Select Case Index
            Case 0 : k = 163
            Case 1 : k = 227
            Case 2 : k = 291
            Case 3 : k = 355
         End Select
         Dim a As String = Decode(bt, k, 32)
         Return a.Trim
      End Get
      Set(ByVal value As String)
         Dim k As Integer
         Select Case Index
            Case 0 : k = 163
            Case 1 : k = 227
            Case 2 : k = 291
            Case 3 : k = 355
         End Select
         bt = Encode(bt, k, value, 32)
      End Set
   End Property 

现在，您需要读取文件并将其放入此类.
从类RandomFile开始

Now you need to read the file and put it into this class.
Start with class RandomFile

#Region " Read File "
   Public Function OpenReader() As e_ioRead '' my enum
      If File.Exists(fpath) Then '' fPath setup in New
         Dim r As Integer
         Do
            Try
               r += 1
               fs = New FileStream(fpath, FileMode.Open, FileAccess.Read, FileShare.None)
               Exit Do
            Catch ex As Exception
               If r > 256 Then Return e_ioRead.Lock
            End Try
         Loop
         sr = New BinaryReader(fs)
         Return e_ioRead.OK
      Else
         Return e_ioRead.Err
      End If
   End Function
   Public Function ReadBytes(ByVal Record As Integer) As Byte()
      Try
         fs.Seek(LineWidth * Record + hk, SeekOrigin.Begin) '' linewidth is width of record x2 if using Encoding
         Dim b() As Byte = sr.ReadBytes(LineWidth)
         Return b
      Catch ex As Exception
         Return Nothing
      End Try
   End Function
   Public Sub CloseReader()
      sr.Close()
      fs.Close()
      fs.Dispose()
   End Sub
#End Region

现在其他地方有这样的东西:-

Now somewhere else have something like this:-

Private Function OpenforRead(ByVal path As String) As Boolean
   mfs = New RandomFile(path)
   Select Case mfs.OpenReader(-1)
      Case e_ioRead.OK
         K = mfs.Count
         Return True
      Case e_ioRead.Lock
         MsgBox(path & " is locked!")
      Case Else
         K = -1
         Return False
   End Select
End Function

Public Function Read() As MyClass
      If OpenforRead() Then
         With mfs
            Try
               CurrentJd = New MyClass
               CurrentJd.Bytes = .ReadBytes(cJob)
            Catch ex As Exception
               MsgBox(ex.Message)
            End Try
            .CloseReader()
         End With
      End If
      Return CurrentJd
   End Function

希望你有主意

Hope you get the idea

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