问如何提取pdf文件中表格的内容？

EN

import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.parser.PdfTextExtractor;

public class PDFReader {

    public static void main(String[] args) {

        // TODO, add your application code
        System.out.println("Lecteur PDF");
        System.out.println (ReadPDF("D:/test.pdf"));
    }
        private static String ReadPDF(String pdf_url)
    {
        StringBuilder str=new StringBuilder();
        try
        {

         PdfReader reader = new PdfReader(pdf_url);
        int n = reader.getNumberOfPages();
         for(int i=1;i<n;i++)
         {
            String str2=PdfTextExtractor.getTextFromPage(reader, i);
            str.append(str2);
           System.out.println(str);
         }
        }catch(Exception err)
        {
            err.printStackTrace();
        }
        return String.format("%s", str);
    }
}