Avoir un lien d'un PDF générer par une servlet (Modal)

 String tempdir = System.getProperty("java.io.tmpdir");
 String downPath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY;
 
                // creates the directory if it does not exist
                File downDir = new File(downPath);
                if (!downDir.exists()) {
                    downDir.mkdir();
                }
 
 
                String filename = "lettre.pdf";
                File temp = new File(downDir + File.separator + filename);
                if (!temp.exists()) {
                    temp.createNewFile();
 
                }
 
 
                Document document = new Document();
                PdfWriter.getInstance(document, new FileOutputStream(temp.getAbsolutePath()));
                document.open();
                addMetaData(document);
                addTitlePage(document);
                addContent(document);
                document.close();

                 PrintWriter out = response.getWriter();
                 String s="";
                 s="success";
                 out.println(s);
                 out.flush();
                 out.close();