Espress Chart

Question

Hi All,
Can you please tell me how to use Espress Chart API to generate a chart in JSP.
It would be really helpfull, if you give me a sample code.
Thanks
Martin

Answer 1

Well, I've not used that, but I've used JFreeChart. First, you need to create the chart. Then there would have to be a method to dump the chart as an image (JPEG or GIF or whatever). So you'd want the page to have an image tag to link to a servlet to output the image. I wouldn't use JSP, I'd use a servlet. So you get the servlet output stream. In the servlet's doGet method:
          ByteArrayOutputStream outBuffer = new ByteArrayOutputStream(1024*50);
          ChartUtilities.writeChartAsPNG(outBuffer, chart, width, height);
          // get buffer's data
          byte[] buf = outBuffer.toByteArray();
          // set response information
          response.setContentType("image/png");
          response.setContentLength(buf.length);
          // write the chart data
          OutputStream out = response.getOutputStream();
          out.write(buf, 0, buf.length);
          // clean up
          outBuffer.close();
          outBuffer = null;
          buf = null;this assumes that the package has something like ChartUtilities.writeChartAs... method.