在C# .NET中使用Syncfusion创建PDF时StreamReader读取Base64字符串的问题求助

Hey there, let's break down what's going wrong here and fix it quickly.

The core issue is this: your GetData() method already returns a Base64-encoded string of the generated PDF. But you're trying to pass that string directly to StreamReader, which expects a stream (like a file or memory stream) as input—not a plain string. That's why you're hitting problems at the StreamReader(result) line.

Even worse, the extra JSON serialization/deserialization step here is totally unnecessary. You're taking a perfectly valid Base64 string, wrapping it in a JSON reader, then converting it back to a string—this can introduce formatting issues or just waste cycles.

Here's the corrected code #

We can strip out the unnecessary stream reader and JSON handling steps entirely, since we already have the Base64 string we need:

using System;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Drawing;
using System.IO;

namespace pdf
{
    class Program
    {
        static void Main(string[] args)
        {
            string pdfBase64 = GetData();
            
            // Convert Base64 string directly to byte array
            byte[] pdfBytes = Convert.FromBase64String(pdfBase64);
            
            // Write bytes to a PDF file (using statements ensure proper resource cleanup)
            using (FileStream fileStream = new FileStream("Sample.pdf", FileMode.Create))
            using (BinaryWriter writer = new BinaryWriter(fileStream))
            {
                writer.Write(pdfBytes, 0, pdfBytes.Length);
            }
            
            System.Diagnostics.Process.Start("Sample.pdf");
        }
        
        static string GetData()
        {
            //Create a new PDF document
            PdfDocument document = new PdfDocument();
            //Add a page to the document
            PdfPage page = document.Pages.Add();
            //Create PDF graphics for the page
            PdfGraphics graphics = page.Graphics;
            //Set the standard font
            PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 20);
            //Draw the text
            graphics.DrawString("Hello World!!!", font, PdfBrushes.Black, new PointF(0, 0));
            
            string imagePath = Path.GetFullPath(@"Data\logo.png");
            //Load the image from the disk with proper stream disposal
            using (FileStream imageStream = new FileStream(imagePath, FileMode.Open, FileAccess.Read))
            {
                PdfBitmap image = new PdfBitmap(imageStream);
                //Draw the image
                graphics.DrawImage(image, 30, 30, 100, 25);
            }
            
            //Save the document into stream with proper cleanup
            using (MemoryStream stream = new MemoryStream())
            {
                document.Save(stream);
                document.Close();
                return Convert.ToBase64String(stream.ToArray());
            }
        }
    }
}

Key improvements made: #

• Removed unused System.Text.Json and Newtonsoft.Json references since JSON handling isn't needed here
• Simplified the Main method: directly use the Base64 string from GetData() to convert to bytes
• Added using statements for all streams to ensure proper resource disposal, preventing memory leaks
• Cleaned up image loading logic with a using block for the image file stream

This should resolve your reading issue and generate the PDF correctly. The Lambda example you referenced uses streams/Base64 for cloud input/output, but in a console app, we can keep things much simpler since we're working directly with local files.

内容的提问来源于stack exchange，提问作者Megatron213