Graph without image jsp

Question

Hello! I’m looking to generate graph by jsp

I tried to follow that tutorial

But only a little square appears in the left corner of the page when I run Filing cabinet Torta.jsp

<%  
    try{
      DefaultPieDataset data = new DefaultPieDataset();    
      while(rs.next()){
          data.setValue(rs.getString("marca"), rs.getInt("TOTAL"));
      }

      JFreeChart grafico = ChartFactory.createPieChart("Cantidad Productos", data, true, true, true);

      response.setContentType("image/JPEG");
      OutputStream sa = response.getOutputStream();

      ChartUtilities.writeChartAsJPEG(sa, grafico, 600,600 );

    }
    catch(Exception ex){
    }
%>

Filing cabinet conexion.jsp

<%
     Class.forName("com.mysql.jdbc.Driver").newInstance();
     Connection cn = DriverManager.getConnection("jdbc:mysql://localhost:3306/producto","root","123");
     Statement cmd= cn.createStatement();
     String sql = "SELECT MARCA, SUM(CANTIDAD) AS TOTAL FROM   PRODUCTO_CANTIDAD GROUP BY MARCA";
     ResultSet rs = cmd.executeQuery(sql);
%>

Screenshot of how the chart appears:

Thank you in advance.

Answer 1

Some possibilities:

1. How you are referencing this image on the page?
2. You tried to run this query in the database to see if it returns data?
3. Tried to put ex.printStackTrace() in the catch to see if there is no error in the execution?