VB.NET中从ListView控件导出数据到CSV文件的问题求助

使用VB.NET开发时需要将ListView中存储的数值导出为CSV文件，需求如下：

• 导出内容仅保留纯数值，无多余格式字符
• 所有数值排布在CSV的同一列，不要分散到多列/多单元格
  当前导出结果显示的是ListBox控件的展示文本而非纯数值，不符合要求。

运行界面截图：

现有导出结果截图：

Imports System.IO
Imports System.IO.StreamReader
Imports System.IO.StreamWriter
Imports System.Data.DataSet

Public Class Form1

    Private Sub startcol_Click(sender As Object, e As EventArgs) Handles startcol.Click
        Timer1.Enabled = True
    End Sub

    Private Sub stopcol_Click(sender As Object, e As EventArgs) Handles stopcol.Click
        Timer1.Enabled = False
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Const MIN As Double = 5.0
        Const MAX As Double = 400.0
        Const DEC_PLACES As Integer = 2

        Dim rnd As New Random
        Dim list As Integer()

        '生成介于MIN到MAX之间的随机数，保留DEC_PLACES位小数
        Dim dbl As Double = Math.Round(rnd.NextDouble() * (MAX - MIN) + MIN, DEC_PLACES)
        weight.Text = dbl

        Dim newItem As New ListViewItem(weight.Text)
        newItem.SubItems.Add(weight.Text)

        'newItem.SubItems.Add(TextBox3.Text)
        ListBox1.Items.Add(newItem)
        ListView1.Items.Add(newItem)
        rowcnt.Text = ListView1.Items.Count
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Timer1.Enabled = True
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Me.DoSave()
    End Sub

    Private Sub DoSave()
        Dim SFD As New SaveFileDialog()
        Try
            With SFD
                .AddExtension = True
                .CheckPathExists = True
                .CreatePrompt = False
                .OverwritePrompt = True
                .ValidateNames = True
                .ShowHelp = True
                .DefaultExt = "txt"
                .Filter = _
                "CSV Files (*.csv)|*.csv|" & _
                "All files|*.*"
                .FilterIndex = 1

                If .ShowDialog() = Windows.Forms.DialogResult.OK Then
                    Me.DoSaveItems(.FileName)
                End If
            End With
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Exclamation, Me.Text)
        End Try
    End Sub

    ' 原有保存方法（存在问题）
    Private Sub DoSaveItems(ByVal fileName As String)
        If fileName Is Nothing = False Then
            If fileName.Length > 0 Then
                Using writer As New System.IO.StreamWriter(fileName)
                    For Each currentItem As Object In Me.ListView1.Items
                        writer.Write(currentItem.ToString() & ",")
                    Next
                End Using
            End If
        End If
    End Sub

    Public Function ExportListViewToCSV(ByVal filename As String, ByVal lv As ListView) As Boolean
        Try
            ' 打开输出文件
            Dim os As New StreamWriter(filename)

            ' 写入表头
            For i As Integer = 0 To lv.Columns.Count - 1
                ' 替换引号避免格式错误
                os.Write("""" & lv.Columns(i).Text.Replace("""", """""") & """,")
            Next
            os.WriteLine()

            ' 写入记录
            For i As Integer = 0 To lv.Items.Count - 1
                For j As Integer = 0 To lv.Columns.Count - 1
                    os.Write("""" & lv.Items(i).SubItems(j).Text.Replace("""", """""") + """,")
                Next
                os.WriteLine()
            Next
            os.Close()
        Catch ex As Exception
            Return False
        End Try
        Return True
    End Function

    Public Sub TestExportToCSV()
        Dim dlg As New SaveFileDialog
        dlg.Filter = "CSV files (*.CSV)|*.csv"
        dlg.FilterIndex = 1
        dlg.RestoreDirectory = True
        If dlg.ShowDialog = Windows.Forms.DialogResult.OK Then
            If ExportListViewToCSV(dlg.FileName, ListView1) Then
                Process.Start(dlg.FileName)
            End If
        End If
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        'TestExportToCSV()
    End Sub
End Class

原有代码存在两个核心问题：

1. 直接调用currentItem.ToString()会返回ListViewItem的类型描述字符串，而非存储的数值文本
2. 用逗号拼接所有数值写在同一行，CSV打开后会分散到同一行的不同列，不符合单列要求

将DoSaveItems方法替换为以下代码即可满足需求：

Private Sub DoSaveItems(ByVal fileName As String)
    If Not String.IsNullOrEmpty(fileName) Then
        Using writer As New System.IO.StreamWriter(fileName)
            For Each currentItem As ListViewItem In Me.ListView1.Items
                ' 直接读取存储的数值文本，每行写一个值，CSV打开后自动归为同一列
                writer.WriteLine(currentItem.Text)
            Next
        End Using
    End If
End Sub

如果需要使用ExportListViewToCSV方法实现需求，修改后的代码如下：

Public Function ExportListViewToCSV(ByVal filename As String, ByVal lv As ListView) As Boolean
    Try
        Using os As New StreamWriter(filename)
            ' 遍历所有行只取第一列的纯数值，不需要表头和额外引号
            For i As Integer = 0 To lv.Items.Count - 1
                os.WriteLine(lv.Items(i).SubItems(0).Text)
            Next
        End Using
    Catch ex As Exception
        Return False
    End Try
    Return True
End Function

修改后导出的CSV仅包含纯数值，所有内容都会显示在第一列，无多余格式字符。

内容的提问来源于stack exchange，提问作者dev-ux