Itextsharp HTMLWorker.Parse错误

Question

我在Windows窗体程序中遇到了来自iTextSharp的HTMLWorker.Parse问题.每当我执行代码并从HTMLWorker.Parse开始时,它都会给出objectDisposedException.例外情况说它无法访问已关闭的文件.但我检查了很多次,找不到关闭的文件.这是代码:

class HtmlToPdfConverter
 {
             private iTextSharp.text.Document doc = new iTextSharp.text.Document();

     public HtmlToPdfConverter()
     {
        this.doc.SetPageSize(PageSize.A4);

     }

     public string Run(string html, string pdfName)
     {
        try
        {
            using (doc)
            {
                StyleSheet styles = new StyleSheet();
                using (PdfWriter writer = PdfWriter.GetInstance(this.doc, new     FileStream(@"Z:\programs\" + pdfName + ".pdf", FileMode.Create)))
                {
                    this.doc.Open();
                    this.doc.OpenDocument();
                    this.doc.NewPage();
                    if (this.doc.IsOpen() == true)
                    {
                        StringReader reader = new StringReader(html);
                        //XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, reader);
                        this.doc.Add(new Paragraph(" "));
                        HTMLWorker worker = new HTMLWorker(this.doc);
                        worker.Open();
                        worker.StartDocument();
                        worker.NewPage();
                        worker.Parse(reader);
                        worker.SetStyleSheet(styles);

                        List<IElement> ie = iTextSharp.text.html.simpleparser.HTMLWorker.ParseToList(reader, null);

                        foreach (IElement element in ie)
                        {
                            this.doc.Add((IElement)element);
                        }

                        worker.EndDocument();
                        worker.Close();
                    }
                }
            }
            return string.Empty;
        }
        catch (Exception ex)
        {
            return ex.Message;
        }

    }
 }

这是例外:

System.ObjectDisposedException was caught
  Message=Cannot access a closed file.
  Source=mscorlib
  ObjectName=""
  StackTrace:
       at System.IO.__Error.FileNotOpen()
       at System.IO.FileStream.Write(Byte[] array, Int32 offset, Int32 count)
       at iTextSharp.text.pdf.OutputStreamCounter.Write(Byte[] buffer, Int32 offset, Int32 count)
       at iTextSharp.text.pdf.PdfIndirectObject.WriteTo(Stream os)
       at iTextSharp.text.pdf.PdfWriter.PdfBody.Add(PdfObject objecta, Int32 refNumber, Boolean inObjStm)
       at iTextSharp.text.pdf.PdfWriter.PdfBody.Add(PdfObject objecta, Int32 refNumber)
       at iTextSharp.text.pdf.PdfWriter.PdfBody.Add(PdfObject objecta, PdfIndirectReference refa)
       at iTextSharp.text.pdf.PdfWriter.AddToBody(PdfObject objecta, PdfIndirectReference refa)
       at iTextSharp.text.pdf.Type1Font.WriteFont(PdfWriter writer, PdfIndirectReference piref, Object[] parms)
       at iTextSharp.text.pdf.FontDetails.WriteFont(PdfWriter writer)
       at iTextSharp.text.pdf.PdfWriter.AddSharedObjectsToBody()
       at iTextSharp.text.pdf.PdfWriter.Close()
       at iTextSharp.text.DocWriter.Dispose()
       at WebPageExtraction.HtmlToPdfConverter.Run(String html, String pdfName)
  InnerException: 

Answer 1

您正在尝试在已经处置后调用close方法.

你有一个using自动处理对象的块,所以只需删除这两行:

doc.CloseDocument();
doc.Close();

如果您不相信内部配置代码正确关闭文档并且想要自己完成,请在using块内执行:

using (doc)
{
    StyleSheet styles = new StyleSheet();
    using (PdfWriter writer = PdfWriter.GetInstance(this.doc, new     FileStream(@"Z:\programs\" + pdfName + ".pdf", FileMode.Create)))
    {
        //.....
    }
    doc.CloseDocument();
    doc.Close();
}

编辑:在为自己尝试代码后,我发现了一些问题并找到了错误的真正原因:

• 您正在关闭并处置全局对象,doc并且从不创建新实例.
• 您不会丢弃所有可能导致内存泄漏或锁定文件的对象.
• 您得到的错误是因为默认情况下,PdfWriter正在关闭它正在使用的Stream,并且在处理时,编写器正在尝试使用此流.因此,要解决此问题,您必须自己关闭流并告诉编写者不要这样做.

完整的固定代码:

Document doc = new Document();
StyleSheet styles = new StyleSheet();
string filePath = @"Z:\programs\" + pdfName + ".pdf";
using (FileStream pdfStream = new FileStream(filePath, FileMode.Create))
{
    using (PdfWriter writer = PdfWriter.GetInstance(doc, pdfStream))
    {
        writer.CloseStream = false;
        doc.Open();
        doc.OpenDocument();
        doc.NewPage();
        if (doc.IsOpen() == true)
        {
            using (StringReader reader = new StringReader(html))
            {
                //XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, reader);
                doc.Add(new Paragraph(" "));
                using (HTMLWorker worker = new HTMLWorker(doc))
                {
                    worker.Open();
                    worker.StartDocument();
                    worker.NewPage();
                    worker.Parse(reader);
                    worker.SetStyleSheet(styles);
                    List<IElement> ie = iTextSharp.text.html.simpleparser.HTMLWorker.ParseToList(reader, null);
                    foreach (IElement element in ie)
                    {
                        doc.Add((IElement)element);
                    }
                    worker.EndDocument();
                    worker.Close();
                }
            }
        }
        writer.Close();
    }
}

doc.CloseDocument();
doc.Close();
doc.Dispose();