Add page number to pdf using pdfstamper(Itext)

问题

I have this code

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        try{
        response.setContentType("application/pdf");
        response.setHeader("Content-Disposition", "inline; filename=details.pdf");
        try{
        Document document = new Document(PageSize.A4, 20, 20, 130, 20);
        PdfWriter writer=PdfWriter.getInstance(document, output);
        document.open();
        BaseFont bf = BaseFont.createFont("c:/windows/fonts/arialuni.ttf", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
        writer.setPageEvent(new HeaderAndFooter(date));
        XMLWorkerHelper worker = XMLWorkerHelper.getInstance();
        List arrlist = new ArrayList();
        List arrlist1 = new ArrayList();//user list
        List arrlist2 = new ArrayList();//time list
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/765a", "root", "root");
        Statement st=con.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
        ResultSet rs=st.executeQuery("SELECT * FROM user_start2 where date='"+date+"' ");
         while(rs.next()){
         arrlist.add(rs.getString("data"));
         arrlist1.add(rs.getString("users"));
         arrlist2.add(rs.getString("strtime"));
         }
         for(int i=0;i<interval+1;i++){
          String str =(String) arrlist.get(i);
          String str1 ='\n'+(String) arrlist1.get(i);
          String str2 =(String) arrlist2.get(i);
          String string =str.replace("<p>","\n").replace("</p>", "\n");
          document.add(new Paragraph(str1+"("+str2+")",new com.itextpdf.text.Font(bf, 10)));
          document.add(new Paragraph(str2,new com.itextpdf.text.Font(bf, 10)));
          document.add(new Paragraph(string,new com.itextpdf.text.Font(bf, 12)));
        }
        document.close();
        response.setContentLength(output.size());
         OutputStream os = response.getOutputStream();
         output.writeTo(os);
         os.flush();
         os.close();
        con.close();
        }catch(IOException e){e.printStackTrace();}
            }catch(IOException e){e.printStackTrace();} 
        catch(DocumentException e) {}
        catch(Exception e) {    
    }
        //PDF READER
          // Create a reader  
        try{
        OutputStream out = new ByteArrayOutputStream(); 
        PdfReader reader = new PdfReader(output.toByteArray());
        PdfStamper stamper = new PdfStamper(reader, out);
        Document document = new Document(); 
        document.open();
        int n = reader.getNumberOfPages();
        PdfContentByte cbq;
        Font headerFont = new Font(FontFamily.COURIER, 13, Font.UNDERLINE);
        for (int i = 1; i <= n; i++) {
            cbq = stamper.getOverContent(i);
             ColumnText ct = new ColumnText( cbq );
             ct.setSimpleColumn( 300 , 300, 50, 50 , 150, Element.ALIGN_CENTER );
              ct.addElement( new Paragraph( "Mathias" , headerFont ) );
              ct.go();
        }
        // Close the stamper
            stamper.close();
            reader.close();
            document.close();
        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

}

I am trying to add page numbers to my pdf but this above code doesnt work.Right now as an example I am just adding text "mathias" to check if it works but the text "mathias" doesnt appear on the pdf page.Everything else works fine,the headers,text on the pdf get displayed but not the data from the stamper.

I also tried using this

 for (int i = 1; i <= n; i++) {
            getHeaderTable(i, n).writeSelectedRows(0, -1, 34, 803, stamper.getOverContent(i));
        }

public static PdfPTable getHeaderTable(int x, int y) {
            PdfPTable table = new PdfPTable(2);
            table.setTotalWidth(527);
            table.setLockedWidth(true);
            table.getDefaultCell().setFixedHeight(20);
            table.getDefaultCell().setBorder(Rectangle.BOTTOM);
            table.addCell("FOOBAR FILMFESTIVAL");
            table.getDefaultCell().setHorizontalAlignment(Element.ALIGN_RIGHT);
            table.addCell(String.format("Page %d of %d", x, y));
            return table;
        }

But nothing appears from the stamper.

Am I missing something?

回答1:

What mkl is trying to explains is very simple. You are sending a PDF document to the browser using:

response.setContentLength(output.size());
OutputStream os = response.getOutputStream();
output.writeTo(os);

However, this document is a PDF document before stamping, hence it shouldn't surprise you that you don't see any changes applied to the document with PdfStamper. Please remove these lines and take a look at this code:

//PDF READER
// Create a reader  
try{
    ByteArrayOutputStream out = new ByteArrayOutputStream(); 
    PdfReader reader = new PdfReader(output.toByteArray());
    PdfStamper stamper = new PdfStamper(reader, out);
    int n = reader.getNumberOfPages();
    PdfContentByte cbq;
    Font headerFont = new Font(FontFamily.COURIER, 13, Font.UNDERLINE);
    for (int i = 1; i <= n; i++) {
        cbq = stamper.getOverContent(i);
        ColumnText ct = new ColumnText( cbq );
        ct.setSimpleColumn( 300 , 300, 50, 50 , 150, Element.ALIGN_CENTER );
        ct.addElement( new Paragraph( "Mathias" , headerFont ) );
        ct.go();
    }
    // Close the stamper
    stamper.close();
    reader.close();
    response.setContentLength(out.size());
    OutputStream os = response.getOutputStream();
    out.writeTo(os);
} catch (DocumentException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Note that I removed the Document document = new Document(); from this snippet. Please read the documentation. You don't need a Document instance when using PdfStamper.

来源：https://stackoverflow.com/questions/21374006/add-page-number-to-pdf-using-pdfstamperitext