vb.net io 操作问题

[tangailingling]

问题如下：
先有一文本文档 a.txt
内容如下：
GMCC,11,11
GMCC,22,22
GMCC,33,33
AMCC,11,11
AMCC,33,33
.........
........
如此类推

用一个DATAGIRD显示文件内容，然后我选中其中的一条修改 然后保存 还有添加功能 小弟对IO操作还不熟悉 项目突然出现问题了 万分感激啊 ！！！！

[allanli]

TextWriter
TextReader

看看msdn下面System.IO命名空间下面的类吧

[hztltgg]

最方便的方法应该是用text文本格式的odbc访问方式来处理

http://www.cnblogs.com/yequancheng/archive/2007/04/23/odbc.html

[zzxap]

GMCC,11,11
GMCC,22,22
GMCC,33,33
AMCC,11,11
AMCC,33,33

把这些数据行列分割放进table里就

[zzxap]

比较麻烦

[DengXingJie]

先说读取：

Option Explicit

Dim Cn As New ADODB.Connection
Dim Rst As New ADODB.Recordset

   'The delimiter can be specified in the registry at the following location:
   'HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Jet \ 4.0 \ Engines \ Text
   '"Format" = "TabDelimited" 用Tab符作分隔符
   'or
   '"Format" = "Delimited(;)" 用指定的符号作分隔符
Private Sub Command1_Click()
   Cn.ConnectionString = "Driver={Microsoft Text Driver (*.txt; *.csv)};Dbq=F:\TEST\杂\各种资料的连接\File;Extensions=asc,csv,tab,txt;HDR=Yes;FMT=Delimited;"
   Cn.Open
   Dim Sql As String
   Sql = "select * from test.txt"
   Rst.CursorLocation = adUseClient
   Rst.Open Sql, Cn, adOpenStatic, adLockPessimistic
   Set DataGrid1.DataSource = Rst
End Sub

[DengXingJie]

楼主要的是VB.NET

Imports System
Imports System.Data
Imports System.Data.OleDb

Public Class Form1

    Dim MyDataSet As DataSet = New DataSet()
    Dim Cn As New OleDb.OleDbConnection
    Dim MyDataAdapterSysSet As OleDbDataAdapter


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If Cn.State = ConnectionState.Open Then
            Cn.Close()
        End If

        Cn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\VS\VS2008\ODBCTextFile\TextFile\;Extended Properties='text;HDR=Yes;FMT=Delimited';"
        Cn.Open()

        Dim SqlStr As String
        SqlStr = "select * from test.txt"

        MyDataAdapterSysSet = New OleDbDataAdapter(SqlStr, Cn)
        MyDataAdapterSysSet.SelectCommand.CommandText = SqlStr
        MyDataAdapterSysSet.Fill(MyDataSet, "tabText") '此名可任取
        DataGridView1.DataSource = MyDataSet.Tables("tabText")

    End Sub
End Class

[DengXingJie]

完整代码

Imports System
Imports System.Data
Imports System.Data.OleDb

Imports System.IO

Public Class Form1

    Dim MyDataSet As DataSet = New DataSet()
    Dim Cn As New OleDb.OleDbConnection
    Dim MyDataAdapterSysSet As OleDbDataAdapter


    Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
        LoadData()
    End Sub


    Private Sub btnWrite_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnWrite.Click
        Dim w As StreamWriter
        w = File.CreateText(Cn.DataSource & "\test.txt")

        Dim nCols As Integer
        Dim nRows As Integer
        Dim i As Integer, j As Integer
        Dim strLine As String

        nRows = DataGridView1.RowCount
        nCols = DataGridView1.ColumnCount

        strLine = DataGridView1.Columns(0).Name
        For j = 1 To nCols - 1
            strLine = strLine & getDelimited() & DataGridView1.Columns(j).Name
        Next
        w.WriteLine(strLine)

        For i = 0 To nRows - 2
            strLine = DataGridView1.Rows(i).Cells(0).Value.ToString
            For j = 1 To nCols - 1
                strLine = strLine & getDelimited() & DataGridView1.Rows(i).Cells(j).Value.ToString
            Next
            w.WriteLine(strLine)
        Next
        w.Close()

        MsgBox("OK")

    End Sub

    Private Sub LoadData()
        If Cn.State = ConnectionState.Open Then
            Cn.Close()
        End If

        Cn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\VS\VS2008\ODBCTextFile\TextFile\;Extended Properties='text;HDR=Yes;FMT=Delimited';"
        Cn.Open()

        Dim SqlStr As String
        SqlStr = "select * from test.txt"

        MyDataSet.Clear()
        DataGridView1.DataSource = Nothing
        MyDataAdapterSysSet = New OleDbDataAdapter(SqlStr, Cn)
        MyDataAdapterSysSet.SelectCommand.CommandText = SqlStr
        MyDataAdapterSysSet.Fill(MyDataSet, "tabText") 
        DataGridView1.DataSource = MyDataSet.Tables("tabText")
    End Sub

    Private Function getDelimited() As String
        Dim key As Microsoft.Win32.RegistryKey
        key = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("SOFTWARE\Microsoft\Jet\4.0\Engines\Text")  
        Dim value As String = CType(key.GetValue("Format"), String)
        If value = "TabDelimited" Then
            getDelimited = vbTab
        Else
            getDelimited = Replace(Replace(value, "Delimited(", ""), ")", "")
        End If
    End Function
End Class

[HAVENT]

使用 System.IO.StreamReader 进行文件流的读取，用System.IO.StreamWriter 进行文件的存储

采用readline的方式一行一行读取，定位记录
用Writeline一行一行的写入记录

这个都比较简单，根据楼主的意思可能需要一个单独的转换方法，将序列化的txt文件记录转换为DataTable对象

这个转换方法也很简单，无非就是独立创建一个DataTable对象，将读取的readline字符串分解为一条DataRow

存储的时候反向写入到TXT文本文件即可，不过这种方式效率是就有点差了，每次保存等于是重写了一次TXT文件