FileStream

Posted on 2016-04-07 Edited on 2023-11-24 In C# Views: Disqus:

以下演示與FileStream配合的資料寫入讀出的範例

一、使用FileStream做創立、寫入設定，並藉由StreamWriter.Write()寫入資料

FileStream filestream = new FileStream(@"d:\stream.txt", FileMode.Create, FileAccess.Write);
string sStringText = "sStringText2";
StreamWriter sw = new StreamWriter(filestream, Encoding.Default);
sw.Write(sStringText);
sw.Close();
filestream.Close();

二、使用FileStream做開啟、讀取設定，並藉由StreamReader.ReadToEnd()讀取資料

filestream = new FileStream(@"d:\stream.txt", FileMode.Open, FileAccess.Read);
StreamReader sr = new StreamReader(filestream, Encoding.Default);
Console.WriteLine(sr.ReadToEnd());
sr.Close();

三、使用FileStream.Write方法將資料寫入檔案(buffer to FileStream instance)

using System;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                //使用FileStream將資料寫入檔案
                FileStream filestream = new FileStream(@"d:\stream.txt", FileMode.Create, FileAccess.Write);
                string sStringText = "sStringText";

                char[] cCharArray = null;
                cCharArray = sStringText.ToCharArray();
                byte[] bBytes = new byte[cCharArray.Length];
                for (int i = 0; i <= cCharArray.Length - 1; i++)
                {
                    bBytes[i] = Convert.ToByte(cCharArray[i]);
                }

                filestream.Write(bBytes, 0, bBytes.Length);
                filestream.Close();

                Console.WriteLine("finish");
                Console.ReadKey();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
                Console.ReadKey();
            }
        }
    }
}

由以上程式可知將字串寫入檔案的方式，是使用FileStream.Write，

是將待寫入的字串先轉成char陣列，然後再轉成byte陣列，

最後利用FileStresm.Write()方法，把byte陣列寫入檔案裡，

開啟檔案就會發現字串sStringText已經寫在裡面了。

值得注意的是，從watch來看，char陣列與byte陣列裡的數值皆為十進位表示，

十進位是轉給開發人員看的，並不表示char與byte就是十進制。

四、FileStream.Write方法與Stream.Read方法的配合應用

using System;
using System.IO;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                WebRequest request = WebRequest.Create("HTTP://images.cnblogs.com/logo_small.gif");
                WebResponse response = request.GetResponse();
                Stream reader = response.GetResponseStream();
                FileStream writer = new FileStream(@"d:\pic.jpg", FileMode.OpenOrCreate, FileAccess.Write);
                byte[] buff = new byte[512];
                int c = 0;

                while ((c = reader.Read(buff, 0, buff.Length)) > 0)
                {
                    writer.Write(buff, 0, c);
                }
                writer.Close();
                writer.Dispose();
                reader.Close();
                reader.Dispose();
                response.Close();
                Console.WriteLine("finish");
                Console.ReadKey();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
                Console.ReadKey();
            }
        }
    }
}

說明：

此範例功能為從網路下載圖片，從網路的stream轉存成檔案的filestream，

此程式主要分為兩部分，一為從網路存資料到緩衝區，第二部分為從緩衝區將資料存成檔案。

一開始為從網路response個stream回來，

然後使用Stream.Read(buff,offset,count)語法為從Stream讀取資料到buff陣列(緩衝區)裡面，

如果程式為每讀一次寫一次則偏移位置可以為零，代表每次都可以覆寫緩衝區，

如為整批讀完整批寫入的話，則每一次的讀取後都需要使用偏移值來指定預寫指標，以防在緩衝區的資料被覆寫到，

每次讀取量通常是由陣列buff.Length指定，讀取量可以小於緩衝區,批次讀取直到讀取完畢，

通常緩衝區會指定的比較小所以無法一次讀完，Stream.Read方法會回傳此次讀取量，

如果已到資料末端時會回傳長度為零。

第二部分從緩衝區資料轉存成檔案，用法與Stream.Read類似，請參考第一範例。

五、FileStream.Write方法與StreamReader.Read方法的配合應用

using System;
using System.IO;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string result = "";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://dotblogs.com.tw/brooke");
            request.Method = WebRequestMethods.Http.Get;
            try
            {
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    Stream stream = response.GetResponseStream();
                    StreamReader streamReader = new StreamReader(stream);
                    char[] buffer = new char[512];//buffer大小可自由設定，通常不會設太大
                    int data = 0;

                    while ((data = streamReader.Read(buffer, 0, buffer.Length)) > 0)
                    {
                        string msg = new string(buffer, 0, data);
                        result = result + msg;
                    }

                    if (streamReader != null) streamReader.Close();
                    if (stream != null) stream.Close();
                }
                if (response != null) response.Close();
            }
            catch (WebException ex1)
            {
                HttpWebResponse exResponse = (HttpWebResponse)ex1.Response;
                Console.WriteLine(ex1.Message);
            }
            catch (NotSupportedException ex2)
            {
                Console.WriteLine(ex2.Message);
            }
            catch (ProtocolViolationException ex3)
            {
                Console.WriteLine(ex3.Message);
            }
            catch (InvalidOperationException ex4)
            {
                Console.WriteLine(ex4.Message);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
            }
        }
    }
}

六、FileStream.Read方法寫到buffer(FileStream instance to buffer)

using System;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            FileStream fs = new FileStream(Directory.GetCurrentDirectory() + @"\pic.png", FileMode.Open);
            int length = (int)fs.Length;
            byte[] buffer = new byte[length];
            int count;
            int sum = 0;
            //fs資料寫到buffer
            //回傳buffer已讀取的總位元組數 FileStream.Read(buffer, buffer的索引「從零開始寫」, 準備要寫入buffer的最大位元組數)
            while ((count = fs.Read(buffer, sum, length - sum)) > 0)
                sum += count;
            fs.Close();
            Console.ReadLine();
        }
    }
}

七、以下為VB.NET範例僅供參考

Imports System.IO
Imports System.Text

'參考網址：http://www.dotblogs.com.tw/yc421206/archive/2009/01/18/6862.aspx
Module Module1

    Sub Main()
        Try
            '***先建立範例檔***
            If Directory.Exists("c:/system_io_test") = False Then
                Directory.CreateDirectory("c:/system_io_test") '建立資料夾與檔案
                File.Create("c:/system_io_test/aaa.txt").Dispose()
                File.Create("c:/system_io_test/aaa2.txt").Dispose()
                File.Create("c:/system_io_test/aaa3.txt2").Dispose()
            End If
            If Directory.Exists("c:/system_io_test/inDir") = False Then
                Directory.CreateDirectory("c:/system_io_test/inDir")
                File.Create("c:/system_io_test/inDir/aaa4.txt").Dispose()
            End If
            File.WriteAllText("c:/system_io_test/aaa.txt", "content1") '將字串content1寫進路徑txt中
            File.WriteAllText("c:/system_io_test/aaa2.txt", "content2") '將字串content2寫進路徑txt中
            File.WriteAllText("c:/system_io_test/aaa3.txt2", "content3") '將字串content3寫進路徑txt中
            File.WriteAllText("c:/system_io_test/inDir/aaa4.txt", "content4") '將字串content4寫進路徑txt中



            '1.Directory列舉目錄與子目錄的方法
            Dim filepaths() As String = Directory.GetFiles("c:\system_io_test\") '列舉出aaa aaa2 aaa3路徑
            Dim bmpFilePaths() As String = Directory.GetFiles("c:\system_io_test", "*.txt2") '列舉出aaa3路徑
            Dim allFilePath() As String = Directory.GetFiles("c:\system_io_test", "*.txt", SearchOption.AllDirectories) '列舉出aaa aaa2 aaa3 aaa4路徑

            '2.File提供檔案建立、複製、移動的靜態方法，並協助建立StreamWriter
            Dim sw As StreamWriter = File.CreateText("c:\system_io_test\CreateText1.txt")
            sw.Write("CreateText1")
            sw.Close()
            File.WriteAllText("c:/system_io_test/aaa.txt", "WriteAllText1") '將字串WriteAllText寫進路徑aaa.txt中
            Dim fileDate As Date = File.GetCreationTime("c:/system_io_test/aaa.txt") '針對aaa.txt檔取得創立時間

            '2.1使用File讀整個檔案，每行塞入字串陣列
            Dim sStrings() As String = File.ReadAllLines("c:/system_io_test/aaa.txt")

            '3.1FileStream資料寫入檔案
            Dim filestream As New FileStream("c:/system_io_test/stream.txt", FileMode.Create, FileAccess.Write)
            Dim sStringText As String = "sStringText"
            Dim cCharText() As Char
            cCharText = sStringText.ToCharArray
            Dim bBytes() As Byte = New Byte(cCharText.Length - 1) {}
            For i = 0 To cCharText.Length - 1
                bBytes(i) = CByte(AscW(cCharText(i)))
            Next
            filestream.Write(bBytes, 0, bBytes.Length)
            filestream.Close()

            '3.1.1 FileStream資料寫入檔案配合StreamWrite
            filestream = New FileStream("c:/system_io_test/stream.txt", FileMode.Create, FileAccess.Write)
            sStringText = "3.1.1FileStream資料寫入檔案配合StreamWrite"
            sw = New StreamWriter(filestream, Encoding.Default)
            sw.Write(sStringText)
            sw.Close()
            filestream.Close()

            '3.2FileStream資料讀出
            filestream = New FileStream("c:/system_io_test/stream.txt", FileMode.Open, FileAccess.Read)
            Dim sr As New StreamReader(filestream, Encoding.Default)
            'Dim sr As New StreamReader(filestream) '第二種寫法
            MsgBox(sr.ReadToEnd())
            sr.Close()

            '4.FileInfo用來幫助File精簡程式
            Dim FileInfo As New FileInfo("c:/system_io_test/info2.txt")
            Dim swOpFileInfo As StreamWriter = FileInfo.CreateText
            swOpFileInfo.WriteLine("test")
            swOpFileInfo.Close()

            MsgBox("完成")
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub

End Module

參考資料：

FileStream 類別

Stream 類別