C# 檔案流（開發者使用方法）

FileStream 使用案例

FileStream 是下列人士的理想選擇

• 直接從檔案讀取或寫入二進位資料。
• 有效率地處理大型檔案。
• 執行異步檔案作業。
• 透過有效使用記憶體來管理系統資源。

基本範例

以下是一個簡單的範例，使用 FileStream 開啟檔案、寫入資料，然後讀取：

using System;
using System.IO;

public class Example
{
    public static void Main()
    {
        string path = "example.txt";

        // Creating a FileStream object to handle the file. The file handle is acquired here.
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            byte[] data = System.Text.Encoding.UTF8.GetBytes("Hello, FileStream!");
            // Write data to file
            fileStream.Write(data, 0, data.Length);
        }

        // Read from the file
        using (FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
        {
            byte[] buffer = new byte[1024];
            int bytesRead = fileStream.Read(buffer, 0, buffer.Length);
            string text = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine(text);
        }
    }
}

using System;
using System.IO;

public class Example
{
    public static void Main()
    {
        string path = "example.txt";

        // Creating a FileStream object to handle the file. The file handle is acquired here.
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            byte[] data = System.Text.Encoding.UTF8.GetBytes("Hello, FileStream!");
            // Write data to file
            fileStream.Write(data, 0, data.Length);
        }

        // Read from the file
        using (FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
        {
            byte[] buffer = new byte[1024];
            int bytesRead = fileStream.Read(buffer, 0, buffer.Length);
            string text = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine(text);
        }
    }
}

本範例示範建立 FileStream 物件，以處理檔案讀寫作業。 FileStream 類別可直接讀寫位元組，因此適合處理大型檔案或二進位資料。 我們使用 Encoding 在文字和位元組之間進行轉換。

使用 FileStream 寫入資料。

若要將資料寫入檔案，您將使用 Write 方法。 以下是一個範例，可以更詳細地說明如何運作：

using System;
using System.IO;

public class FileWriteExample
{
    public static void Main()
    {
        string path = "output.txt";

        // Creating a FileStream object to write data to the file
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            byte[] buffer = System.Text.Encoding.UTF8.GetBytes("Writing data to FileStream.");
            int offset = 0;
            int count = buffer.Length;

            // Writing data to the file
            fileStream.Write(buffer, offset, count);
        }
    }
}

using System;
using System.IO;

public class FileWriteExample
{
    public static void Main()
    {
        string path = "output.txt";

        // Creating a FileStream object to write data to the file
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            byte[] buffer = System.Text.Encoding.UTF8.GetBytes("Writing data to FileStream.");
            int offset = 0;
            int count = buffer.Length;

            // Writing data to the file
            fileStream.Write(buffer, offset, count);
        }
    }
}

在此程式碼中，我們使用 UTF8 編碼將字串轉換為位元組陣列。 Write 方法會從目前位置 (由偏移量決定) 開始寫入位元組到檔案，並寫入指定的位元組數量。

• FileMode.Create 會建立新檔案，並覆寫任何具有相同名稱的現有檔案。
• FileAccess.Write 授予 FileStream 的寫入權限。

使用 FileStream 讀取資料。

現在，讓我們探索如何使用 FileStream 從檔案讀取資料。

using System;
using System.IO;

public class FileReadExample
{
    public static void Main()
    {
        // File path
        string path = "output.txt";

        // File Stream Object
        using (FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
        {
            byte[] buffer = new byte[1024];
            int bytesRead = fileStream.Read(buffer, 0, buffer.Length);
            // Output Stream
            string output = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine(output);
        }
    }
}

using System;
using System.IO;

public class FileReadExample
{
    public static void Main()
    {
        // File path
        string path = "output.txt";

        // File Stream Object
        using (FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
        {
            byte[] buffer = new byte[1024];
            int bytesRead = fileStream.Read(buffer, 0, buffer.Length);
            // Output Stream
            string output = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine(output);
        }
    }
}

在這個範例中

• FileMode.Open 開啟現有檔案。
• Read 方法讀取指定數量的位元組（基於緩衝區大小）並將其儲存到位元組緩衝區中。
• 我們使用 Encoding.UTF8.GetString 將位元組資料轉換回字串。

處理檔案位置

每次讀取或寫入檔案時，FileStream 都會追蹤檔案中的目前位置。您可以使用 Position 屬性存取此位置：

fileStream.Position = 0; // Move to the beginning of the file

fileStream.Position = 0; // Move to the beginning of the file

IronPDF 與 FileStream

以下是使用 IronPDF 生成 PDF 并将其保存到 FileStream 的示例。 這展示了 IronPDF 如何與 FileStream 順利整合，讓開發人員可以程式化地控制 PDF 的建立與儲存。

using System;
using System.IO;
using IronPdf;

public class IronPDFExample
{
    public static void Main()
    {
        // Define the file path
        string path = "output.pdf";

        // Create an HTML string that we want to convert to PDF
        var htmlContent = "<h1>IronPDF Example</h1><p>This PDF was generated using IronPDF and saved with FileStream.</p>";

        // Initialize IronPDF's ChromePdfRenderer to render HTML as PDF
        var renderer = new ChromePdfRenderer();

        // Generate the PDF from the HTML string
        var pdfDocument = renderer.RenderHtmlAsPdf(htmlContent);

        // Use FileStream to save the generated PDF
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            pdfDocument.SaveAs(fileStream);
        }

        Console.WriteLine("PDF created and saved successfully.");
    }
}

using System;
using System.IO;
using IronPdf;

public class IronPDFExample
{
    public static void Main()
    {
        // Define the file path
        string path = "output.pdf";

        // Create an HTML string that we want to convert to PDF
        var htmlContent = "<h1>IronPDF Example</h1><p>This PDF was generated using IronPDF and saved with FileStream.</p>";

        // Initialize IronPDF's ChromePdfRenderer to render HTML as PDF
        var renderer = new ChromePdfRenderer();

        // Generate the PDF from the HTML string
        var pdfDocument = renderer.RenderHtmlAsPdf(htmlContent);

        // Use FileStream to save the generated PDF
        using (FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write))
        {
            pdfDocument.SaveAs(fileStream);
        }

        Console.WriteLine("PDF created and saved successfully.");
    }
}