iText PDF：文档没有页面

Question

我正在尝试使用基于日期范围的过滤器将报告导出为 PDF；但是，当我单击导出 PDF 时，我收到以下消息： ExceptionConverter: java.io.IOException: 文档没有页面。这是我的 PDF class' 代码：

import com.itextpdf.text.Document;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfWriter;
import java.io.FileOutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.swing.JOptionPane;

public class PDFPrinter {
    private String date1;
    private String date2;
    public void printpdf(){
    try {
            
            String file_name = JOptionPane.showInputDialog("Digite o nome do arquivo: ");
            String file_place = "C:\";
            String file_name_and_place = "C:\File\" + file_name + ".pdf";
            Document document = new Document();           
            PdfWriter.getInstance(document,new FileOutputStream(file_name_and_place));
            document.open();
            ConnectionFactory myConn = new ConnectionFactory();
            Connection connection = myConn.getConnection();
            PreparedStatement ps = null;
            ResultSet rs = null;
            String query = "SELECT * FROM tb_pacientes";
            ps = connection.prepareStatement(query);
            rs=ps.executeQuery();
            
            while(rs.next()){
                PdfPTable table = new PdfPTable(3);
        
                Paragraph para = new Paragraph(rs.getString("UID")+" "+rs.getString("Name")+" "+rs.getString("Address")+" "+rs.getString("Age")+" "+rs.getString("Frontline")+" "+rs.getString("VaccinationDate")+" "+rs.getString("Priority"));
                document.add(para);
                document.add(new Paragraph(" "));
                
            }
            document.close();
            JOptionPane.showMessageDialog(null, "Seu arquivo foi criado com sucesso em "+file_name_and_place);
        }         
        catch (Exception e) {
            JOptionPane.showMessageDialog(null, "Ocorreu um erro, tente novamente, por favor.");
            e.printStackTrace();
        }
}
    public void printPDFWithFilter(String date1, String date2){
        this.date1 = date1;
        this.date2 = date2;
        ConnectionFactory factory= new ConnectionFactory();
        try(Connection c = factory.getConnection()){
            String file_name = JOptionPane.showInputDialog("Digite o nome do arquivo: ");
            String file_place = "C:\";
            String file_name_and_place = "C:\File\" + file_name + ".pdf";
            Document document = new Document();           
            PdfWriter.getInstance(document,new FileOutputStream(file_name_and_place));
            document.open();
            ConnectionFactory myConn = new ConnectionFactory();
            Connection connection = myConn.getConnection();
            PreparedStatement ps = null;
            ResultSet rs = null;
            String query = "SELECT * FROM tb_pacientes WHERE VaccinationDate BETWEEN ? AND ?";
                         
            ps = connection.prepareStatement(query);
            ps.setString(1, "%" +date1+ "%");
            ps.setString(2, "%" +date2+ "%");
            rs=ps.executeQuery();            
            while(rs.next()){
                PdfPTable table = new PdfPTable(3);        
                Paragraph para = new Paragraph(rs.getString("UID")+" "+rs.getString("Name")+" "+rs.getString("Address")+" "+rs.getString("Age")+" "+rs.getString("Frontline")+" "+rs.getString("VaccinationDate")+" "+rs.getString("Priority"));
                document.add(para);
                document.add(new Paragraph(" "));                
            }
            document.close();
            JOptionPane.showMessageDialog(null, "Seu arquivo foi criado com sucesso em "+file_name_and_place);
        }
        catch(Exception e){
            e.printStackTrace();
            StringWriter sw = new StringWriter();
            PrintWriter pw = new PrintWriter(sw);
            e.printStackTrace(pw);
            String sStackTrace = sw.toString(); 
            System.out.println(sStackTrace);
            if (sStackTrace == "ExceptionConverter: java.io.IOException: The document has no pages."){
              JOptionPane.showMessageDialog (null,"Selecione as datas novamente; com as configurações atuais, o documento não teria páginas.");
            }
            else{
              JOptionPane.showMessageDialog(null, "Ocorreu um erro ao filtrar o PDF; por favor, tente novamente.");  
            }            
        }
    }
}

下面是 PDF 生成按钮的代码：

   private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
  String date1 = jDateChooser1.getDate().toString();
  String date2 = jDateChooser2.getDate().toString();
  PDFPrinter pdfp = new PDFPrinter();
  pdfp.printPDFWithFilter(date1, date2);
    }

我认为 SQL 和 JDateChooser 有问题，因为它的日期格式似乎与 SQL 的 DATE 格式不兼容，但我不确定，我还没有找不到任何改变它的方法，所以，我在这里寻求帮助。

Answer 1

您的 SQL 请求似乎没有 return 任何行，
将您的 PdfTable(3) 从 while() 中删除；

Answer 2

好吧，在bigtheo的回答和一点点毅力的帮助下，我能够解决问题哈哈；好吧，问题出在第二种方法中优先级列表中的百分比符号上。我只是擦掉了它们，它起作用了！

iText PDF：文档没有页面

iText PDF: the document has no pages

java

sql

pdf

itext