JFreeChart，開放源碼的Java圖表生成組件（基于LGPL Licence），可以創建餅圖、曲線圖、柱狀圖、甘特圖，生成PNG,JPG等圖片格式文件。當前最新版本為0.9.11，下面就是一張JFreeChart生成的統計圖。本文講解如何在Web利用JFreeChart生成餅狀統計圖。
一、安裝配置
當前最新版本為0.9.11
下載jfreechart-0 .9.11.zip
下載jfreechar t-0.9.11.tar.gz
解壓縮文件，jfreechart-0.9.11目錄下的jfreechart-0.9.11.jar和 lib/jcommon-0.8.6.jar,lib/gnujaxp.jar都是開發運行需要的文件，把這三個文件放置到應用的lib目錄下。
然后在web.xml文件中增加以下內容：
<servlet>
<servlet-name>DisplayChart</servlet-name>
<servlet-class>org.jfree.chart.
servlet.DisplayChart</servlet-class>
</servlet>/PRE> |
/CENTER>
安裝配置完成，現在可以寫程序生成我們需要的統計圖了。
二、開始，在JSP中生成餅型統計圖
<%@ page contentType=
"text/html;charset=GBK"%>
<%@ page import=
"org.jfree.data.DefaultPieDataset"%>
<%@ page import=
"org.jfree.chart.JFreeChart"%>
<%@ page import=
"org.jfree.chart.plot.PiePlot"%>
<%@ page import=
"org.jfree.chart.
ChartRenderingInfo"%>
<%@ page import=
"org.jfree.chart.servlet.
ServletUtilities"%>
<%@ page import=
"org.jfree.chart.urls.
StandardPieURLGenerator"%>
<%@ page import=
"org.jfree.chart.entity.
StandardEntityCollection"%>
<%
DefaultPieDataset data
= new DefaultPieDataset();
data.setValue("六月",500);
data.setValue("七月",580);
data.setValue("八月",828);
PiePlot plot = new PiePlot(data);
JFreeChart chart = new JFreeChart
("",JFreeChart.DEFAULT_TITLE_FONT,
plot, true);
chart.setBackgroundPaint
(java.awt.Color.white);
//可選，設置圖片背景色
chart.setTitle
("www.SenTom.net 網站訪問統計表");
//可選，設置圖片標題
ChartRenderingInfo info
= new ChartRenderingInfo
(new StandardEntityCollection());
//500是圖片長度，300是圖片高度
String filename =
ServletUtilities.saveChartAsPNG
(chart, 500, 300, info, session);
String graphURL =
request.getContextPath() +
"/servlet/DisplayChart?filename="
+ filename;
%>
<HTML>
<HEAD>
<TITLE>www.sentom.net</TITLE>
</HEAD>
<BODY>
<P ALIGN="CENTER">
<ccid_file values="<%=" graphURL % />"
width=500 height=300 border=0
usemap="#<%= filename
%>">
</P>
</BODY>
</HTML>/PRE> |
/CENTER>
就這么簡單，生成的餅狀圖如下
三、JSP+JAVABEAN生成餅狀統計圖
WebChart.java
/*
* Created on 2003-9-9
* http://www.sentom.net
* To change the template
for this generated file go to
* Window>Preferences>Java>Code
Generation>Code and Comments
*/
package net.sentom.chart;
import java.awt.Insets;
import java.awt.Font;
import java.io.PrintWriter;
import javax.servlet.http.HttpSession;
import org.jfree.data.*;
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.chart.entity.*;
import org.jfree.chart.urls.*;
import org.jfree.chart.servlet.*;
import org.jfree.chart.labels.
StandardPieToolTipGenerator;
/**
* @author sentom
*
* To change the template for
this generated type comment go to
* Window>Preferences>Java>Code
Generation>Code and Comments
*/
public class WebChart
{
private DefaultPieDataset data =
new DefaultPieDataset();
public void setValue
(String key,double value)
{
data.setValue(key,value);
}
public String generatePieChart
(String title, HttpSession session,
PrintWriter pw)
{
String filename = null;
try
{
//創建chart對象
PiePlot plot =
new PiePlot(data);
plot.setInsets
(new Insets(0, 5, 5, 5));
//在統計圖片上建連結
plot.setURLGenerator
(new StandardPieURLGenerator
("link.jsp","section"));
plot.setToolTipGenerator
(new StandardPieToolTipGenerator());
JFreeChart chart = new JFreeChart
("", JFreeChart.DEFAULT_TITLE_FONT,
plot, true);
chart.setBackgroundPaint
(java.awt.Color.white);
//設置圖片的背景色
Font font = new Font
("黑體",Font.CENTER_BASELINE,20);
//設置圖片標題的字體和大小
TextTitle _title =
new TextTitle(title);
_title.setFont(font);
chart.setTitle(_title);
//把生成的圖片放到臨時目錄
ChartRenderingInfo info =
new ChartRenderingInfo(new
StandardEntityCollection());
//500是圖片長度，
300是圖片高度
filename = ServletUtilities.
saveChartAsPNG
(chart, 500, 300, info,
session);
ChartUtilities.writeImageMap
(pw, filename, info);
pw.flush();
} catch (Exception e)
{
System.out.println
("Exception - " + e.toString());
e.printStackTrace
(System.out);
filename =
"public_error_500x300.png";
}
return filename;
}
}/PRE> |
/CENTER>
JSP文件
<%@ page contentType=
"text/html;charset=GBK"%>
<%@ page import =
"java.io.PrintWriter" %>
<%@ page import=
"net.sentom.chart.WebChart"%>
<%
WebChart chart = new WebChart();
chart.setValue("六月",500);
chart.setValue("七月",580);
chart.setValue("八月",828);
String filename =
chart.generatePieChart
("www.SenTom.net 網站訪問統計表",
session, new
PrintWriter(out));
String graphURL =
request.getContextPath() +
"/servlet/DisplayChart?filename="
+ filename;
%>
<HTML>
<HEAD>
<TITLE>www.sentom.net</TITLE>
</HEAD>
<BODY>
<P ALIGN="CENTER">
<ccid_file values="<%=" graphURL % />
" width=500 height=300
border=0 usemap="#<%=
filename %>">
</P>
</BODY>
</HTML>/PRE> |
生成的餅狀圖如下
四 參考資源
http://sourceforge.net/projects/jfreechart
http://www.jfree.org/jfreechart/index.html
http://www.jfree.org/phpBB2/viewforum.php?f=3