Question

I’m trying to generate a pdf file from data in a database using JasperReports with a java servlet. The first time I generated a pdf file successfully with data in database. Then I made some changes in my database table and recreated jrxml file and created a jasper file using that jrxml file. But now when I am trying to generate a pdf, the pdf file is always empty.

Code in my Servlet

response.setContentType("application/pdf");
try {

    HttpSession hs = request.getSession();
    String id = (String) hs.getAttribute("id");

    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/exam", "root", "pass");
    Statement statement = con.createStatement();
    ResultSet resultSet = statement.executeQuery 
            ("SELECT marks, date_time FROM result where sub_id = 1  and user_id = 3");

    ServletOutputStream set = response.getOutputStream();
    InputStream re = getServletConfig().getServletContext().getResourceAsStream("./results.jasper");
    JRResultSetDataSource resultSetDataSource = new JRResultSetDataSource(resultSet);
    JasperRunManager.runReportToPdfStream(re,set, new HashMap(), resultSetDataSource);

} catch (Exception e) {

}

How could I solve this?

Answer 1

Change every catch to

...
} catch (Exception e) { 
    e.printStackTrace(); 
}

That will provide details of what is going wrong, and where.