安装这两个库，第二个库一定要安装否则有些pdf文件读取会出现异常

读取

using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Canvas.Parser;
using iText.Kernel.Pdf.Canvas.Parser.Listener;namespace TestReadPdf
{public static class PdfHelper{public static IEnumerable<string> ExtractText(string filename){using (var r = new PdfReader(filename))using (var doc = new PdfDocument(r)){for (int i = 1; i < doc.GetNumberOfPages(); i++){ITextExtractionStrategy strategy = new LocationTextExtractionStrategy();string text = PdfTextExtractor.GetTextFromPage(doc.GetPage(i), strategy);yield return text;}}}}
}