使用iTextSharp读取PDF文档会创建具有重复首页的字符串 [英] Reading PDF document with iTextSharp creates string with repeating first page

问题描述

我目前使用iTextSharp读取一些PDF文件，并使用收到的字符串对其进行解析.我在处理某些PDF文件时遇到了奇怪的行为.当获取例如4页PDF的字符串时，该字符串将按以下顺序用页面填充:

I currently use iTextSharp to read in some PDF files and parse them by using the string I receive. I have encountered a strange behavior with some PDF files. When getting the string back of a for example 4 page PDF, the string is filled with the pages in the following order:

1 2 1 3 1 4

1 2 1 3 1 4

我读取文件的代码如下:

My code for reading the files is as follows:

using (PdfReader reader = new PdfReader(fileStream))
{
     StringBuilder sb = new StringBuilder();

     ITextExtractionStrategy strategy = new SimpleTextExtractionStrategy();
     for (int page = 0; page < reader.NumberOfPages; page++)
     {
         string text = PdfTextExtractor.GetTextFromPage(reader, page + 1, strategy);
         if (!string.IsNullOrWhiteSpace(text))
             sb.Append(Encoding.UTF8.GetString(Encoding.Convert(Encoding.Default, Encoding.UTF8, Encoding.Default.GetBytes(text))));
     }

     Debug.WriteLine(sb.ToString());
}

这里是发生此行为的文件的链接:

Here is a link to a file with which this behaviour occurs:

https://onedrive.live .com/redir?resid = D9FEFF3BF45E05FD！1536& authkey =！AFLRlskAvlg89yY& ithint = file％2cpdf

希望你们能帮助我！

推荐答案

感谢克里斯·哈斯(Chris Haas)，我发现自己出了问题.在网上找到的有关如何使用iTextSharp.Pdf的示例对于我的实现不正确或不正确.

Thanks to Chris Haas I found out was going wrong. The samples found online on how to use iTextSharp.Pdf are incorrect or incorrect for my implementation.

您尝试读取的每个页面都必须实例化SimpleTextExtractionStrategy.如果不这样做，则会在结果字符串中乘以每个上一页.

The SimpleTextExtractionStrategy needs to be instantiated for every page you try to read. Not doing this will multiply each previous page in the resulting string.

另外，可以将StringBuilder附加到的行更改为:

Also the line where the StringBuilder is being appended can be changed from:

sb.Append(Encoding.UTF8.GetString(Encoding.Convert(Encoding.Default, Encoding.UTF8, Encoding.Default.GetBytes(text))));

到

sb.Append(text);

因此以下代码给出了正确的结果:

Thus the following code gives the correct result:

using (PdfReader reader = new PdfReader(fileStream))
{
    StringBuilder sb = new StringBuilder();

    for (int page = 0; page < reader.NumberOfPages; page++)
    {
        string text = PdfTextExtractor.GetTextFromPage(reader, page + 1, new SimpleTextExtractionStrategy());
        if (!string.IsNullOrWhiteSpace(text))
            sb.Append(text);
    }
    Debug.WriteLine(sb.ToString());                    
}

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