import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import org.jfree.chart.*;
import org.jfree.data.category.*;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.xy.*;
import org.jfree.data.*;
import org.jfree.chart.renderer.category.*;
import org.jfree.chart.plot.*;
import java.awt.*;

public class ChartServlet extends HttpServlet {

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
        throws IOException, ServletException
    {
		response.setContentType("image/png");
		ServletOutputStream sos = response.getOutputStream();
		JFreeChart chart = getBarChart();
		ChartUtilities.writeChartAsPNG(sos, chart, 400, 400);
    }

	public JFreeChart getBarChart() {
		DefaultCategoryDataset dataset = new DefaultCategoryDataset();
		dataset.setValue(2, "Marks", "Rahul");
		dataset.setValue(7, "Marks", "Vinod");
		dataset.setValue(4, "Marks", "Deepak");
		dataset.setValue(9, "Marks", "Prashant");
		dataset.setValue(6, "Marks", "Chandan");
		JFreeChart chart = ChartFactory.createBarChart (
		"BarChart using JFreeChart","Student", "Marks", dataset, 
		PlotOrientation.VERTICAL, false,true, false);
		chart.setBackgroundPaint(Color.yellow);
		chart.getTitle().setPaint(Color.blue); 
		CategoryPlot p = chart.getCategoryPlot(); 
		p.setRangeGridlinePaint(Color.red); 
		return chart;
	}
}