jfreechart servlet to jsp

Question

my problem: i have a jsp where a button press will send a ID to the servlet. with the iD, my Servlet will send it further to a method, to use a sql statement to fetch data from the database base on the id. it all works fine, even the chart.

but now i want to include the chart back to my jsp and let the user see it without changing sites. with the outputstream it will stay on the servlet, and if i want to change my data, i need to go back. i tried going for the saveasPng route, but java always say that path was not found.

any help is appreciated.

OutputStream outputStream = response.getOutputStream();
        response.setContentType("image/png");
        int width = 500;
        int height = 350;
        ChartUtilities.writeChartAsPNG(outputStream, chart, width, height);
        
//       try {
//           final ChartRenderingInfo info = new 
//            ChartRenderingInfo(new StandardEntityCollection());
//
//            final File file1 = new File(request.getContextPath() + "WebContent/images/piechart.png");
//            ChartUtilities.saveChartAsPNG(
//             file1, chart, 600, 400, info);
//            System.out.println("hallo TRue");
//            } catch (Exception e) {
//            e.printStackTrace();
//            }
         request.setAttribute("imagePath", request.getContextPath() + "/WebContent/images/piechart.png");
         request.setAttribute("chart", chart);
         //request.getRequestDispatcher("Diagramm.jsp").forward(request, response);

Are you asking [_How to call servlet through a JSP page_](https://stackoverflow.com/q/5649722/230513)? — trashgod, Nov 01 '20 at 14:04
@trashgod well my problem is that i want to display the jfreechart on my jsp. right now it is displayed in the servlet, after pressing the button in the jsp. — thobbe, Nov 01 '20 at 20:31
Why not create a servlet for just the chart, and include it as needed? — trashgod, Nov 01 '20 at 21:20

score 1 · Answer 1 · edited Nov 03 '20 at 12:01

I see two different approaches here:

Add JavaScript to your JSP page and using AJAX patterns to invoke your servlet and modify dynamically the content of the JSP page within the browser with the result.
Refresh your JSP page adding a static HTML IMG tag where you invoke the servlet with the new ID parameter within the SRC attribute of the IMG tag. Something like <IMG src="/MyServlet?ID=xxx" width="500" height="350">

jfreechart servlet to jsp

1 Answers1