閱讀/寫作大文件VB.NET

Question

我是一個新用戶，並與下方掙扎：

我需要讀取該文件，並與一些修改，寫回，問題是：

1. 「ReadToEnd」適用於較小文件[約100MB]，一切正常，我喜歡做的事情。 但是對於更大的文件[300 MB +]，它會彈出。
2. 然後我嘗試「的ReadLine」（讀逐行） 它適用於更小的或更大的文件不錯，但它需要非常非常長的救回來。

我既包括下面的「ReadToEnd的」和「的ReadLine」 代碼測試你的需要創建「100MB-FILE.TXT」和「300MB-FILE.TXT」文件在C：\ TEMP \區域。

我真的很感激在這方面

'----------------Reading whole File ReadToEnd 
Dim sr As New StreamReader("C:\temp\100MB-File.txt") 
Dim path As String = "C:\temp\myFileNew1.txt" 
Dim oneLine As String 
oneLine = sr.ReadToEnd 
Using sw As StreamWriter = File.CreateText(path) 
    sw.WriteLine(oneLine) 
End Using 
sr.Close() 

''---------------Reading Line by Line 
Dim sr As New StreamReader("C:\temp\300MB-File.txt") 
Dim path As String = "C:\temp\myFileNew2.txt" 
Dim oneLine As String 
oneLine = sr.ReadLine 

Using sw As StreamWriter = File.CreateText(path) 
    sw.WriteLine(oneLine) 
End Using 

Do Until sr.EndOfStream 
    Console.WriteLine(oneLine) 
    oneLine = sr.ReadLine() 

    Using sw As StreamWriter = File.AppendText(path) 
     sw.WriteLine(oneLine) 
    End Using 
Loop 
sr.Close() 

Answer 1

除了在評論中，你打開和關閉你正在寫的每一行輸出文件中提到的Console.WriteLine你的幫助。如果你只是打開該文件一次，它應該會快很多：

Dim sr As New StreamReader("C:\temp\300MB-File.txt") 
Dim path As String = "C:\temp\myFileNew2.txt" 
Dim oneLine As String 
oneLine = sr.ReadLine 

Using sw As StreamWriter = File.CreateText(path) 
    sw.WriteLine(oneLine) 
    Do Until sr.EndOfStream 
     'Console.WriteLine(oneLine) 
     oneLine = sr.ReadLine() 
     sw.WriteLine(oneLine) 
    Loop 
End Using 

sr.Close() 

你也可以使用File.ReadLines簡化代碼：

Dim inPath As String = "C:\temp\300MB-File.txt" 
Dim outPath As String = "C:\temp\myFileNew2.txt" 

Using sw As StreamWriter = File.CreateText(outPath) 
    For Each oneLine As String In File.ReadLines(inPath) 
     ' modify line here 
     sw.WriteLine(oneLine) 
    Next 
End Using