我有一个jsp，它调用一个servlet来创建pdf文件。

public class HelloWorld extends Action
  {
     public static final String RESULT= "C:\hello.pdf";

     public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
     {
        try {
           new HelloWorld().createPdf(RESULT);
        } catch (Exception e) {
           e.printStackTrace();
           return mapping.findForward("Failure");
        }
        return mapping.findForward("Success");
     }

     public void createPdf(String filename) throws IOException, DocumentException {
        Document document = new Document();
        PdfWriter.getInstance(document, new FileOutputStream(filename));
        document.open();
        PdfPTable table = createTable1();
        document.add(table);
        document.close();
     }

     public static PdfPTable createTable1() throws DocumentException {
        ...
     }
  }

我希望有一个类似“另存为”的消息框，而不是静态路径 C:\hello.pdf