使用 vb.net 从具有 100k 行的文本文件中轻松快速地加载数据网格

Question

我用VB.net创建了一个程序，其中文本文件用于加载数据网格，但它非常慢，有很多代码，当从文本文件有很多行导入时。

有没有更简单的编码方式，所以数据网格加载不会那么慢？

Private Sub Load_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Load.Click

OpenFileDialog1.Filter = "Text Files|*.txt|All Files|*.*"
    OpenFileDialog1.Title = "Select Text File for Path"
    OpenFileDialog1.FileName = "Select File"
    If OpenFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.Ok Then
        txttblnm.Text = OpenFileDialog1.FileName
        txtfilenm.Text = System.IO.Path.GetFileName(txttblnm.Text)
        txtfilenm.Text = txtfilenm.Text.Substring(0, txtfilenm.Text.Length - 4)
        Label7.Text = System.IO.Path.GetDirectoryName(txttblnm.Text)
    End If

    If Len(txtfilenm.Text) = 8 And CheckBox1.CheckState = CheckState.Checked Then
        Dim textfiles() = Directory.GetFiles(Label7.Text, "*.txt")
        For Each file As String In textfiles
            Call dgv1_load()
            Call Access_export()
            Call clear_item()
        Next
    ElseIf Len(txtfilenm.Text) >= 9 Then
        MsgBox("Please Load DATA", MsgBoxStyle.Information, "Load Data Error")
        Exit Sub
    End If
End Sub

Answer 1

您与用户界面的交互过多。与 gridview + 文本框的每次交互都是昂贵的。

您应该首先创建一个 DataTable 并用行数据填充它。

然后在所有加载完成后，将 datagridview.DataSource 设置为该表，所有内容都将只绘制一次。

    Private Function ParseFile(filename As String) As DataTable
        Dim result As New DataTable()
        result.Columns.Add("colname 1 ....")
        result.Columns.Add("colname 2 ....")

        Using inputFile As New StreamReader(filename) 'Open text file

            Do Until inputFile.EndOfStream
                Dim row = result.Rows.Add()
                row(0) = "blah"
            Loop
        End Using
        return result
    End Function

    Private Sub ShowResult()
        dgv1.DataSource = ParseFile(filename)
    End Sub