C#高效的读取大型文本文件的方法

ufferedStream+FileStream+StreamReader

开个10M缓冲池，然后加上异步，速度飞飞的。

 

[VB.NET][C#.NET] MemoryStream / BufferedStream 類別

 

MemoryStream 跟 StringReader / StringWriter 類別用法差不多，但兩者還是些微不同；MemoryStream可以將已經寫入記憶體的資料，直接另存到實體檔案，而StringWriter不能直接存。

        private void button1_Click(object sender, EventArgs e)

        {

            //引用MemoryStream類別

            MemoryStream myMem = new MemoryStream();

            //引用StreamWriter類別

            StreamWriter myWriter = new StreamWriter(myMem);

            //寫資料至記憶體

            myWriter.Write("寫資料至:");

            myWriter.WriteLine("記憶體(Memory)");

            //寫資料至檔案

            myWriter.Flush();

            FileStream myFile = File.Open(@"C:/myFile.txt", FileMode.OpenOrCreate);

            myMem.WriteTo(myFile);

            //釋放

            myFile.Dispose();

            myWriter.Dispose();

            myMem.Dispose();

        }

 

 

 

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        '引用MemoryStream類別

        Dim myMem As MemoryStream = New MemoryStream()

        '引用StreamWriter類別

        Dim myWriter As StreamWriter = New StreamWriter(myMem)

        '寫資料至記憶體

        myWriter.Write("寫資料至:")

        myWriter.WriteLine("記憶體(Memory)")

        '寫資料至檔案

        myWriter.Flush()

        Dim myFile As FileStream = File.Open("C:/myFile.txt", FileMode.OpenOrCreate)

        myMem.WriteTo(myFile)

        '釋放

        myFile.Dispose()

        myWriter.Dispose()

        myMem.Dispose()

    End Sub

 

 

BufferedStream 類別，是將緩衝層加入另一資料流上的讀寫。

有時候直接將資料寫入檔案效能並不好，由其是在處理大筆資料時，為了提高處理效率可以使用BufferedStream 類別，將資料寫入緩衝區內，當緩衝區被全部清除輸出時，資料才會真正的被寫入資料。

        private void button2_Click(object sender, EventArgs e)

        {

            FileStream myFile = File.Open(@"C:/myFile.txt", FileMode.Create, FileAccess.Write, FileShare.Write);

            BufferedStream myBuf = new BufferedStream(myFile);

            StreamWriter myWrite = new StreamWriter(myBuf);

            myWrite.Write("寫入緩衝區");

            myWrite.WriteLine("步驟還真麻煩");

            myBuf.Flush();

            //釋放

            myWrite.Dispose();

            myBuf.Dispose();

            myFile.Dispose();

        }

 

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Dim myFile As FileStream = File.Open("C:/myFile.txt", FileMode.Create, FileAccess.Write, FileShare.Write)

        Dim myBuf As BufferedStream = New BufferedStream(myFile)

        Dim myWrite As StreamWriter = New StreamWriter(myBuf)

        myWrite.Write("寫入緩衝區")

        myWrite.WriteLine("步驟還真麻煩")

        myBuf.Flush()

        '釋放

        myWrite.Dispose()

        myBuf.Dispose()

        myFile.Dispose()

    End Sub

 

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