How to invoke a servlet generating an image ?

Hello,

I am using a Servlet that generates a PNG image using JFreeChart on a
Tomcat 6.0 server.

I would like to test the servlet but in don't know how to invoke it
from my brower. I tried to open the URL http://localhost:8080/myapp/ServletBarChart
but Tomcat displays an error saying that the file could not be found.

Here is my servlet file :

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.data.*;
import org.jfree.data.category.*;

public class ServletBarChart extends HttpServlet {

  protected void service(HttpServletRequest request,
HttpServletResponse response)
    throws ServletException, IOException {

    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    dataset.addValue(120000.0, "Produit 1", "2000");
    dataset.addValue(550000.0, "Produit 1", "2001");
    dataset.addValue(180000.0, "Produit 1", "2002");
    dataset.addValue(270000.0, "Produit 2", "2000");
    dataset.addValue(600000.0, "Produit 2", "2001");
    dataset.addValue(230000.0, "Produit 2", "2002");
    dataset.addValue(90000.0, "Produit 3", "2000");
    dataset.addValue(450000.0, "Produit 3", "2001");
    dataset.addValue(170000.0, "Produit 3", "2002");

    JFreeChart barChart = ChartFactory.createBarChart("Evolution des
ventes", "",
      "Unite vendue", dataset, PlotOrientation.VERTICAL, true, true,
false);
    OutputStream out = response.getOutputStream();
    response.setContentType("image/png");
    ChartUtilities.writeChartAsPNG(out, barChart, 400, 300);
  }
}

What am I doing wrong ?

Fabzy