VB.net - 更快的文本操作/存储到数组

Question

我必须编写一个程序来读取 .txt 文件中的字符串，并处理数据以返回各种结果。 我遇到的问题是执行时间。

    Dim OpenAnswerFile As New OpenFileDialog
    OpenAnswerFile.Multiselect = True
    Dim strFileName() As String '// String Array.
    Dim tempStr As String = "" '// temp String for result.
    Dim FileName As String
    Dim Watcher As New Stopwatch
    If OpenAnswerFile.ShowDialog = DialogResult.OK Then 
        Watcher.Restart()
        For Each FileName In OpenAnswerFile.FileNames

            strFileName = IO.File.ReadAllLines(FileName) 
            For Each myLine In strFileName 
                tempStr &= myLine & vbNewLine 
            Next

        Next
        Watcher.Stop()
        Dim TimeToArrays = Watcher.Elapsed
        Watcher.Reset()
        '========================WRITE TO FILE
        Dim file As System.IO.StreamWriter
        file = My.Computer.FileSystem.OpenTextFileWriter("c:\test.txt", True)
        Watcher.Restart()
        file.Write(tempStr)
        file.WriteLine(TimeToArrays)
        file.WriteLine(Watcher.Elapsed)
        Watcher.Stop()
        file.Close()

        '========================WRITE TO FILE

    End If

将这个从 A 到 Z 运行到字典样式的 txt 文件大约需要一分钟，我发现总共只有超过 1MB 的文件。

有什么方法可以加快整个过程？

Answer 1

试试这个代码 - 它在 6.5 秒内运行近 90Mb 的文件。

对代码的更改可以总结为：

• 检查 DialogResult 并且在这部分例程完成之前不要迭代文件。

• 在读取操作期间，使用Using...End Using 来提高IO 效率。

• 使用List(of String) 来保存数据，而不是继续附加到字符串。从内存管理的角度来看，我认为这更有效。使用其他集合可能有更快的方法。

• 在写操作过程中，使用Using...End Using来提高IO效率。

代码如下：

Sub DoItQuicker()

    Dim OpenAnswerFile As New OpenFileDialog
    OpenAnswerFile.Multiselect = True
    Dim strFileName() As String '// String Array.
    Dim strSingleFileContent As String
    Dim strFileData As New List(Of String)
    Dim FileName As String
    Dim Watcher As New Stopwatch

    'get user feedback
    If OpenAnswerFile.ShowDialog <> DialogResult.OK Then
        MessageBox.Show("Not OK")
        Exit Sub
    Else
        strFileName = OpenAnswerFile.FileNames
    End If
    OpenAnswerFile.Dispose()

    'read data
    Watcher.Restart()
    For Each FileName In OpenAnswerFile.FileNames

        Using sr As New IO.StreamReader(FileName)
            strSingleFileContent = sr.ReadToEnd
            For Each line As String In strSingleFileContent.Split(vbLf)
                strFileData.Add(line)
            Next
        End Using

    Next
    Watcher.Stop()
    Dim TimeToArrays = Watcher.Elapsed
    Debug.Print(Watcher.ElapsedMilliseconds)

    'write data
    Watcher.Restart()
    Using sw As New IO.StreamWriter("D:\temp\out.txt")
        For Each line As String In strFileData
            sw.WriteLine(line)
        Next
        sw.WriteLine(TimeToArrays)
        sw.WriteLine(Watcher.Elapsed)
    End Using
    Watcher.Stop()
    Debug.Write(Watcher.ElapsedMilliseconds)


End Sub