9.  Creating server side graphics and forms 

9.1  Foreword 

This chapter provides some insight about how to create server side graphs and forms. These examples are 

quite rough and they should not be taken  as good all around solutions. There are many third party tools 

that can be used to create better looking graphics and maybe a bit easier, too. 

9.2  Graphs 

The basic idea is to use a third party graph toolset to create your desired graph and then send the graph 

image to the client browser. There are two options in getting the result image back to client browser: Either 

(a) stream it directly using a 

HttpServletResponse 

object provided by JSP container or (b) store the 

image to a file and provide a link to the file back to the client browser. Followed are examples of both by 

creating a simple graph with Sitraka JClass Chart tools 

(

com.klg.jclass.chart.beans.SimpleChart

). At least JBuilder6 Pro is shipped with a development 

version of the tools. 

9.2.1  Example of streaming a graph image back to the client browser 

The first example shows a JSP listing of how to create the graph, encode it to a PNG image and how to 

stream it to the client browser. The listing uses a tool function shipped with e FixIT 4.2 that wraps around 

Java Advanced Imaging (JAI) 1.1 tools. The tools are freely available at 

http://java.sun.com/products/java 

media/jai/

. Many commercial graph creation tools also contain methods to converting graph  to several 

image formats.  

<% 

  response.reset(); 

/* Init the chart object and set it's size */ 

  com.klg.jclass.chart.beans.SimpleChart chart = new 

com.klg.jclass.chart.beans.SimpleChart(); 

  chart.setSize(new java.awt.Dimension(500,300)); 

/* Fetch the graph data using a XfijFinder component. The graph will show 

lengths of lab test results (field number  6  in file  80001 ) in a simple plot 

graph connected with lines. */ 

  xfij.core.XfijFinder finder = new xfij.core.XfijFinder(); 

  finder.setFileNumber(new xfij.editor.FileNumber("80001")); 

  finder.setWRPCBroker(laboratoriotutkimusBean.getBroker()); 

  finder.setFields(new String[] { "6" }); 

  String[] results = finder.getList(); 

/* Create a TableModel that is used as data source by the graph component*/

  javax.swing.table.TableModel model = 

xfij.util.ChartUtil.ResultsToTableModel(results, false); 

  chart.setSwingDataModel(model); 

  chart.setXAxisTitleText("Record number"); 

  chart.setYAxisTitleText("The length of result"); 

  chart.repaint(); 

/* Create the source image and stream it as PNG image ( testImage.png ) back to 

the client browser. The browser detects the stream and will ask for the user to 

redirect the PNG image*/ 

  xfij.util.ChartUtil.encode(chart.serverSnapshot(),"PNG","testImage",response); 

%> 

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