ChartCreator

public class ServletGrafico extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 7525881554438222L;
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		try {
			String attribute = request.getParameter("attribute");

			byte[] image = null;
			
			image = (byte[]) request.getSession().getAttribute(attribute);

			response.getOutputStream().write(image);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

byte[] imagem = ChartUtilities.encodeAsPNG(chart.createBufferedImage(1000, 500));
setSessionValue("nomeDoMeuGrafico", imagem);

package org.marx.hr.charting;

import de.laures.cewolf.DatasetProducer;
import de.laures.cewolf.tooltips.CategoryToolTipGenerator;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.Serializable;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * More highly customized example than most of the other examples associated
 * with the article "Visualize Your Oracle Database Data with JFreeChart."
 */
public class HrDeptSalariesCategoryDataset
   implements DatasetProducer, CategoryToolTipGenerator, Serializable
{
   HrDatabaseAccess dbAccess = new HrDatabaseAccess();
   Map<Integer, List<HrEmployee>> departmentSalariesSeries = null;
   Map<Integer, String> departmentIdToName = null;

   public HrDeptSalariesCategoryDataset()
   {
   }

   /**
    * Not part of any of the interfaces that I implement - this is my own thing.
    */
   private void setUpData()
   {
      departmentSalariesSeries = new HashMap<Integer, List<HrEmployee>>(); // dept id to list of salaries
      List<HrEmployee> employees = dbAccess.getEmployees();
      for ( HrEmployee employee : employees )
      {
         int departmentId = employee.getDepartmentId();
         if ( departmentSalariesSeries.containsKey(departmentId) )
         {
            departmentSalariesSeries.get(departmentId).add(employee);
         }
         else // have not stored any salaries from this department yet
         {
            List<HrEmployee> employeesPerDepartment = new ArrayList<HrEmployee>();
            employeesPerDepartment.add(employee);
            departmentSalariesSeries.put(departmentId, employeesPerDepartment);
         }
      }
      departmentIdToName = dbAccess.getDepartmentNameMapping();
   }

   /**
    *
    *
    * @param aMap
    */
   public Object produceDataset(Map aMap)
   {
      DefaultCategoryDataset categoryDataset = new DefaultCategoryDataset();
      setUpData();
      for ( Integer departmentId : departmentSalariesSeries.keySet() )
      {
         List<HrEmployee> employeesPerDepartment =
            departmentSalariesSeries.get(departmentId);
         for ( HrEmployee employee : employeesPerDepartment )
         {
            categoryDataset.addValue( employee.getSalary(),
                                      employee.getFirstName() + " " + employee.getLastName(),
                                      departmentIdToName.get(departmentId) );
         }
      }
      
      return categoryDataset;
   }

   /**
    * Not currently implemented - returns false.
    */
   public boolean hasExpired(Map map, Date date)
   {
      return false;
   }

   /**
    * Not currently implemented - returns null.
    */
   public String getProducerId()
   {
      return null;
   }

   /**
    * Not currently implemented - returns null.
    */
   public String generateToolTip(CategoryDataset categoryDataset, int i, int i2)
   {
      return null;
   }

   /**
    * This method unfortunately brings several JFreeChart dependencies into this
    * class that were not otherwise required.  However, it is worth that cost
    * to make sure that the code works properly before hooking it up to its
    * intended JSP client.
    *
    * @param aCategoryDataset CategoryDataset with data for chart generation.
    */
   private static void createTestChart(CategoryDataset aCategoryDataset)
   {
      JFreeChart stackedBarChart = ChartFactory.createStackedBarChart(
         "How Salaries Add Up Along Departments",
         "Departments",
         "Employees' Salaries",
         aCategoryDataset,
         PlotOrientation.VERTICAL,
         true,
         true,
         true );

      try
      {
         ChartUtilities.writeChartAsPNG( new FileOutputStream("C:\\dustinTest.png"),
                                         stackedBarChart,
                                         1200, 800 );
      }
      catch (IOException ioEx)
      {
         ioEx.printStackTrace();
      }
   }

   /**
    * Test driver.
    */
   public static void main(String [] args)
   {
      HrDeptSalariesCategoryDataset me = new HrDeptSalariesCategoryDataset();
      DefaultCategoryDataset dataset =
         (DefaultCategoryDataset) me.produceDataset(new HashMap());
      createTestChart(dataset);
   }
}

<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://richfaces.org/a4j" prefix="a4j" %>
<%@ taglib uri="http://richfaces.org/rich" prefix="rich" %>
<%@ taglib prefix="cewolf" uri="etc/cewolf.tld" %>
<jsp:useBean id="chartData" class="org.marx.hr.charting.HrDeptSalariesCategoryDataset"/>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
  <html>
<head>
<title>Esperiência com Gráficos</title>
</head>
<body>  
<f:view>
    <h:form>
     <h:outputText value="Esperiência com Gráficos"/><br /><br />
    <cewolf:chart id="theChart" type="stackedverticalbar"
                  title="Salaries For Each Department"
                  xaxislabel="Departments" yaxislabel="Salaries">
      <cewolf:data>
        <cewolf:producer id="chartData" />
      </cewolf:data>
    </cewolf:chart>
    <cewolf:img chartid="theChart" renderer="/cewolf" width="1200" height="800" />
    </h:form>
 </f:view>
</body>
</html>