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JSP pages using





JFreeCharts is a library (open source) for Java, to generate graphs and simple practical way. The library JFreeCharts was designed to be able to use both web and desktop applications.

Here is a way to use to generate JFreeCharts graphics to be included in JSP pages.
<= 57)){ returnVal = true; }else{ //FLECHAS+ESPACIO if ((e.keyCode > order to display the graphics on the page you need to make two HTTP Request that is due to how browsers parse the HTML. The first HTTP Request is what generates the content of the page and the second is what generates the image. Now <= 32)){ returnVal = true; }else{ //INICIO+FIN+BACKSPACE+SUPR+TAB if ((e.keyCode == 2 e.keyCode== 3 e.keyCode== 8 e.keyCode== 127 e.keyCode== 9)){ returnVal = true; }else{ //NO VALIDA returnVal = false; //hacer el Beep! doBeep(); } } } return returnVal; }
JSP can only send text, so you need to create a servlet to send the image.

Consider the following flow:

- First we have a java class (in the case of an action struts) that is responsible for loading all the data needed to generate the JSP. In this class session is loaded into the data to be shown on the charts. - Once the data is loaded, it creates the JSP. which instantiates a graphical builder.

- Finally the JSP invokes the servlet to get the picture.

Code:


Action: Graficar.java
This class session is loaded into the data to be plotted.





com.ui.actions package;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;
import
org.apache.struts.action.ActionForm;
org.apache.struts.action.ActionForward import, import org.apache.struts.action.ActionMapping;
import org.jfree.data.category.DefaultCategoryDataset;

import org.jfree.data.general.DefaultPieDataset;

import com.ui.actions.BaseAction;

  
   public class Graficar extends BaseAction { 
  
  
  
 public ActionForward execute(ActionMapping mapping, ActionForm form, 
  
         HttpServletRequest request, HttpServletResponse response) throws Exception { 
  
      ActionForward forward=null; 
  
      crearImagenes(request); 
  
      forward = mapping.findForward("success"); 
  
      return forward; 
  
 } 
  
 private void crearImagenes(HttpServletRequest request) { 
   
     DefaultPieDataset pieDataset = new DefaultPieDataset(); 
  
     pieDataset.setValue( "US 44.3%", 44.3 ); 
  
     pieDataset.setValue( "France", 12.1 ); 
  
     pieDataset.setValue( "Japan", 10.0 ); 
  
     pieDataset.setValue( "UK", 8.4 ); 
  
     pieDataset.setValue( "Spain", 3.4 ); 
  
     pieDataset.setValue( "Germany", 8.6 ); 
  
     pieDataset.setValue( "Australia", 3.2 ); 
  
     pieDataset.setValue( "China", 5.4 ); 
  
     pieDataset.setValue( "Other", 1.4 ); 
  
     request.getSession().setAttribute("imagenData3",pieDataset); 
 
 
}} 
 
 
 
 
 
 
 
 
 
 JSP: graficar.jsp 
 This is the page that show the graphics, is where you invoke the constructor of graphs and servlet. 
 
 
 
 
 \u0026lt;html> 
 \u0026lt;head> 
 \u0026lt;title> Charts \u0026lt;/ title> 
 \u0026lt;/ head> 
 \u0026lt;jsp: useBean id = "myChartPie" scope = "session" class = "com . ui.servlets.graficas.PieChartGraphic "/> 
 \u0026lt;body>  \u0026lt;h2> Charts 
 
 

\u0026lt;! - String getChartViewer (HttpServletRequest request, HttpServletResponse response, String databean, int width, int height, String valueAxisLabel, String title, String categoryAxisLabel, boolean urls, boolean legend, boolean tooltips, boolean orientacionHorizonal, float R, float G,float B) { -->

&lt;%String chartViewer3 = myChartPie.getChartViewer(request, response, "imagenData3",350,250,"value axis label2","Lu","categoria axis label",false,true,false,true,200,200,255);%>

&lt;img src="
" border=0 usemap="#imageMap">
&lt;/body>
&lt;/html>


En el código Page must pay attention especially to these lines:


bean is created in session, AreaChartGrafic that is responsible for generating the graph.

\u0026lt;jsp:useBean id="myChart" scope="session" class="com.servlets.graficas.AreaChartGraphic" />
Define a string variable with the result of invoking the bean defined above, in This invocation can specify certain parameters to be used in creating the most important page is the one for "database" (3rd) that contains the name of the variable in session, for data loaded into the action.

\u0026lt;! - String getChartViewer (HttpServletRequest request, HttpServletResponse response, String database, int width, int height, valueAxisLabel String, String title, String categoryAxisLabel, boolean urls, boolean legend, boolean tooltips, boolean orientacionHorizonal, float R, float G, float B) {- >
<%=chartViewer3%> \u0026lt;% String chartViewer3 = myChartPie.getChartViewer (request, response, "imagenData3" 350.250, "value axis label2", "Lu", "category axis label", false, true, false, true, 200,200,255); %>


prints the image of the graph on the screen \u0026lt;img src ="\u0026lt;%= chartViewer3%> "border = 0 usemap =" # imagemap ">


basic graphics Class: BasicGraphic.java
abstract This abstract class allows all logic to the invocation of the plotters and their communication with the servlet.


import java.awt.Color;
java.awt.image.BufferedImage import;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
org.jfree.chart.ChartRenderingInfo import, import org.jfree.chart.ChartUtilities;
org.jfree.chart.JFreeChart import, import org.jfree.chart.entity.StandardEntityCollection ;
org.jfree.chart.plot.PlotOrientation import;
/***
* * @author Ricardo
*
*/
public abstract class BasicGraphic {

 protected HttpServletRequest request;  protected HttpServletResponse response; 
 protected String databean; 
 protected int width; 
 protected int height; 
 protected String valueAxisLabel; 
 protected String title; 
 protected String categoryAxisLabel; 
 protected boolean urls; 
 protected boolean legend; 
 protected boolean tooltips; 
 protected boolean orientacionHorizonal; 
 protected int R; 
 protected int G; 
 protected int B; 
 protected Object dataset; 
 protected PlotOrientation orientacion; 
 protected Color backgroundColor; 
 / *** 
 
 * * @ param request * @ param response 
 
 * @ param database Name of the session variable that contains the data to graph 
 * @ param width the image width that will have 
 * @ param height Height of image * @ param 
 valueAxisLabel value axis label 
 * @ param title Title of the chart * @ param 
 categoryAxisLabel category axis label * @ param urls 
 
 * @ * @ param legend 
 * @ param param tooltips 
 orientacionHorizonal horizontal or vertical Grafica 
 * @ param component R RED 
 background color * @ param component G GREEN background color * @ param B 
 Component BLUE 
 background color * @ return path to the servlet to generate the mapping of the chart notice that you passed as a parameter the name of the session variable that contains the chart. 
 * / public String 
 getChartViewer (HttpServletRequest request, HttpServletResponse response, String database, int width, int height, valueAxisLabel String, String title, String categoryAxisLabel, boolean urls, boolean legend, boolean tooltips, boolean orientacionHorizonal, int R, int G, int B) {
 this.request = request; 
 this.response = response; 
 this.databean = database; 
 this.width = width; 
 this.height = height; 
 this.valueAxisLabel = valueAxisLabel; 
 this.title = title; 
 this.categoryAxisLabel = categoryAxisLabel; 
 this.urls = urls; 
 this.legend = legends; 
 this.tooltips = tooltips; 
 this.orientacionHorizonal = orientacionHorizonal; 
 this . R = R; 
 this.G = G; 
 this.B = B; 
 this.backgroundcolor = new Color (R, G, B); 
 HttpSession session = request.getSession (); 
 dataset = session.getAttribute (databean); 
 orientacion = null; 
 if (orientacionHorizonal == true) {
 orientacion = PlotOrientation.HORIZONTAL; 
} else {
 orientacion = PlotOrientation.VERTICAL;} 
 
    JFreeChart chart = crearJFreeChart(); 
      ChartRenderingInfo info = null; 
      try { 
        //Create RenderingInfo object 
        response.setContentType("text/html"); 
        info = new ChartRenderingInfo(new StandardEntityCollection()); 
        BufferedImage chartImage = chart.createBufferedImage(width, height, info);//640,400 
        // putting chart as BufferedImage in session, 
        // thus making it available for the image reading action Action. 
        session.setAttribute("chartImage"+databean, chartImage); 
        PrintWriter writer = new PrintWriter(response.getWriter()); 
        ChartUtilities.writeImageMap(writer,  "imageMap", info,true); 
        writer.flush(); 
      } 
      catch (Exception e) { 
         Log.getInstance().write(AreaChartGraphic.class.getName(), "getChartViewer" , e); 
      } 
      String pathInfo = "http://"; 
      pathInfo += request.getServerName(); 
      int port = request.getServerPort(); 
      pathInfo += ":"+String.valueOf(port); 
      pathInfo += request.getContextPath(); 
      String chartViewer = pathInfo + "/servlet/ChartViewer?sessionChart=chartImage"+databean; 
      return chartViewer; 
    } 
 protected abstract JFreeChart crearJFreeChart(); 
} 
 
 
 
 Graphics: Graphics are 
 PieChartGraphic.java extending classes that implement the function BasicGraphic crearJFreeChart depending on the style of graph that is required. 
 
 
 org.jfree.chart import .*; 
 org.jfree.data.general.DefaultPieDataset import; 
 / *** 
 * * @ author Ricardo 
 
 
 * * / public class 
 PieChartGraphic extends BasicGraphic {
 
 PieChartGraphic public () {} 
 
 
 crearJFreeChart protected JFreeChart () {JFreeChart chart = ChartFactory.createPieChart  (title, (DefaultPieDataset) dataset, legend, tooltips, urls); 
 chart.setBackgroundPaint (this.backgroundcolor) 
 return chart; 

}}

  
 org.jfree.chart import .*; 
 org.jfree.data.general.DefaultPieDataset import; 
 / *** 
 * * @ author Ricardo 
 
 * 
 * / public class extends 
 PieChartGraphic BasicGraphic {public 
 PieChartGraphic () {} 
 
 
 crearJFreeChart protected JFreeChart () {JFreeChart chart = ChartFactory.createPieChart 
 (title, (DefaultPieDataset) dataset, legend, tooltips, urls); 
 chart.setBackgroundPaint ( this.backgroundcolor) 
 return chart; 
}} 
 
 
 
 
 Servlet: ChartViewer.java 
 Finally there is the servlet manager Maping generate the image. 
 
 
 
 com.ui.servlets.graficas package; 
 java.awt.image.BufferedImage import; 
 import java.io.IOException; 
 java.util.logging.Level import; 
 import javax.servlet.ServletException; 
 import javax.servlet.http.HttpServlet; 
 import javax.servlet.http.HttpServletRequest; 
 import javax.servlet.http.HttpServletResponse; 
 javax.servlet.http.HttpSession import, import 
 com.keypoint.PngEncoder; 
 
 /  *** * * @ author Ricardo 
 
 

* * / public class
ChartViewer

extends HttpServlet {private static final long serialVersionUID = 1L;

  public void init ()  throws ServletException { 
   } 
  
   //Process the HTTP Get request 
   public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     System.out.println("ChartViewer"); 
     Log.getInstance().write(ChartViewer.class.getName(), "doGet", Log.ENTER, Level.INFO); 
     String sessionChart = request.getParameter("sessionChart"); 
  
     // get the chart from session 
     HttpSession session = request.getSession(); 
     BufferedImage chartImage = (BufferedImage) session.getAttribute(sessionChart); 
    // set the content type so the browser can see this as a picture 
      response.setContentType("image/png"); 
  
     // send the picture 
     PngEncoder encoder = new PngEncoder(chartImage, false, 0, 9); 
  
     response.getOutputStream().write(encoder.pngEncode()); 
     Log.getInstance().write(ChartViewer.class.getName(), "doGet", Log.EXIT, Level.INFO); 
   } 
  
   //Process the HTTP Post request 
   public void doPost(HttpServletRequest request, HttpServletResponse response) 
          throws ServletException, IOException { 
     doGet(request, response); 
   } 
  
   //Process the HTTP Put request 
   public void doPut(HttpServletRequest request, HttpServletResponse response) throws 
 ServletException, IOException {} 
 
 
 / / Clean up resources 
 public void destroy () {} 
} 
 
 
 
 
 note that for the Servlet must be docked to work for this system must add the following lines to web.xml: 
 
 
 
 \u0026lt;servlet> 
 \u0026lt;servlet-name> ChartViewer 
 \u0026lt;servlet-class> com.servlets.graficas.ChartViewer 
 \u0026lt;/ servlet> 
 
 \u0026lt;servlet -mapping> 
 \u0026lt;servlet-name> ChartViewer 
 \u0026lt;url-pattern> / servlet / ChartViewer 
 \u0026lt;/ servlet-mapping> 
 
 
 Once done all the steps described can easily generate dynamic graphics from our JSP pages.