JFreeChart-饼状图-初级

JFreeChart，开放源码的Java图表生成组件（基于LGPL Licence），可以创建饼图、 曲线图、柱状图、甘特图，生成PNG,JPG等图片格式文件。当前最新版本为0.9.11，右边是一张JFreeChart生成 的统计图。本文讲解如何在Web利用JFreeChart生成饼状统计图。

一 安装配置
	当前最新版本为0.9.11
	下载jfreechart-0 .9.11.zip
	下载jfreechar t-0.9.11.tar.gz
	解压缩文件，jfreechart-0.9.11目录下的jfreechart-0.9.11.jar和 lib/jcommon-0.8.6.jar,lib/gnujaxp.jar都是开发运行需要的文件，把这三个文件放置到应用的lib目录下。
	然后在web.xml文件中增加以下内容：
	<servlet> <servlet-name>DisplayChart</servlet-name> <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class> </servlet>
	安装配置完成，现在可以写程序生成我们需要的统计图了。
二 开始，在JSP中生成饼型统计图
	<%@ 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);//可选，设置图片背景色 chart.setTitle("www.SenTom.net 网站访问统计表");//可选，设置图片标题 ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection()); //500是图片长度，300是图片高度 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"> <img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#<%= filename %>"> </P> </BODY> </HTML>
	就这么简单，生成的饼状图如下
三 高级，JSP+JAVABEAN生成饼状统计图
	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 { //创建chart对象 PiePlot plot = new PiePlot(data); plot.setInsets(new Insets(0, 5, 5, 5)); //在统计图片上建连结 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);//设置图片的背景色 Font font = new Font("黑体",Font.CENTER_BASELINE,20);//设置图片标题的字体 和大小 TextTitle _title = new TextTitle(title); _title.setFont(font); chart.setTitle(_title); //把生成的图片放到临时目录 ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection()); //500是图片长度，300是图片高度 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; } }
	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 网站访问统计表", session, new PrintWriter(out)); String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename; %> <HTML> <HEAD> <TITLE>www.sentom.net</TITLE> </HEAD> <BODY> <P ALIGN="CENTER"> <img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#<%= filename %>"> </P> </BODY> </HTML>
	生成的饼状图如下