iTextSharp 创建的 PDF 仍在使用中

Question

如果我使用给定的源代码创建 pdf，我会遇到无法打开 pdf 文档的问题，例如 "adobe-acrobat"，因为它说它仍在被另一个进程使用.我在释放锁的代码中缺少什么？

var a = Guid.NewGuid();

Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);

PdfWriter writer2 = PdfWriter.GetInstance(pdfDoc, new FileStream(a.ToString()+".pdf", FileMode.Create));
writer2.SetFullCompression();
writer2.CloseStream = true;

iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(AppContext.BaseDirectory + "Ehrungsantrag.png");
img.SetAbsolutePosition(0, 0);
img.ScaleAbsoluteHeight(pdfDoc.PageSize.Height);
img.ScaleAbsoluteWidth(pdfDoc.PageSize.Width);
pdfDoc.Open();
pdfDoc.NewPage();
pdfDoc.Add(img);

pdfDoc.Close();
writer2.Close();

Answer 1

错误是没有关闭FileStream。同样正如@Amy 已经提到的，您需要确保执行了清理代码，例如：

Document pdfDoc = null;
PdfWriter writer2 = null;
System.IO.FileStream fs = null; // <- create the FileStream

try
{
   var a = Guid.NewGuid();
   pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);

   fs =  new FileStream(a.ToString()+".pdf", FileMode.Create);
   writer2 = PdfWriter.GetInstance(pdfDoc, fs);
   writer2.SetFullCompression();
   writer2.CloseStream = true;

   iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(AppContext.BaseDirectory + "Ehrungsantrag.png");
   img.SetAbsolutePosition(0, 0);
   img.ScaleAbsoluteHeight(pdfDoc.PageSize.Height);
   img.ScaleAbsoluteWidth(pdfDoc.PageSize.Width);

   pdfDoc.Open();
   pdfDoc.NewPage();
   pdfDoc.Add(img);
}
finally
{
        pdfDoc.Close();
        pdfDoc = null;

        //writer2.Close(); 

       // That was the eroor -> always close open filehandles explicity !
       fs.Close(); 
}

Answer 2

var a = Guid.NewGuid();

using (var pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f))
using (var writer2 = PdfWriter.GetInstance(pdfDoc, new FileStream(a.ToString()+".pdf", FileMode.Create));
{
    writer2.SetFullCompression();
    writer2.CloseStream = true;

    iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(AppContext.BaseDirectory + "Ehrungsantrag.png");
    img.SetAbsolutePosition(0, 0);
    img.ScaleAbsoluteHeight(pdfDoc.PageSize.Height);
    img.ScaleAbsoluteWidth(pdfDoc.PageSize.Width);
    pdfDoc.Open();
    pdfDoc.NewPage();
    pdfDoc.Add(img);

    pdfDoc.Close();
    writer2.Close()
}

iTextSharp 创建的 PDF 仍在使用中

iTextSharp Created PDF is still in use

c#

itext

asp.net-core-mvc