利用JFreechart画饼状图(一)

web.xml

<?xml version="1.0"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<servlet>
		<servlet-name>DisplayChart</servlet-name>
		<servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>DisplayChart</servlet-name>
		<url-pattern>/DisplayChart</url-pattern>
	</servlet-mapping>
</web-app>

demo.jsp

<%@ page contentType="text/html;charset=GBK"%>
<%@ page
	import="org.jfree.chart.*,org.jfree.chart.plot.PiePlot,org.jfree.data.general.DefaultPieDataset,org.jfree.chart.servlet.ServletUtilities,java.awt.*"%>
<%
	//设置数据集
	DefaultPieDataset dataset = new DefaultPieDataset();
	dataset.setValue("初中高级程序员", 0.55);
	dataset.setValue("项目经理", 0.1);
	dataset.setValue("系统分析师", 0.1);
	dataset.setValue("软件架构师", 0.1);
	dataset.setValue("其他", 0.2);
	//通过工厂类生成JFreeChart对象
	JFreeChart chart = ChartFactory.createPieChart3D("IT行业职业分布图",
			dataset, true, false, false);
	PiePlot pieplot = (PiePlot) chart.getPlot();
	pieplot.setLabelFont(new Font("宋体", 0, 12));
	//没有数据的时候显示的内容
	pieplot.setNoDataMessage("无数据显示");
	pieplot.setCircular(false);
	pieplot.setLabelGap(0.02D);
	String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300,
			null, session);
	String graphURL = request.getContextPath()
			+ "/DisplayChart?filename=" + filename;
%>
<img src="<%=graphURL%>" width=500 height=300 border=0
	usemap="#<%= filename %>">