利用JFreechart绘制饼状图(二)

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.servlet.ServletUtilities,org.jfree.util.Rotation,org.jfree.data.general.DefaultPieDataset,org.jfree.chart.plot.PiePlot3D"%>
<%
	//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, true, false);
	//获得3D的水晶饼图对象
	PiePlot3D pieplot3d = (PiePlot3D) chart.getPlot();
	//设置开始角度
	pieplot3d.setStartAngle(150D);
	//设置方向为”顺时针方向“
	pieplot3d.setDirection(Rotation.CLOCKWISE);
	//设置透明度，0.5F为半透明，1为不透明，0为全透明
	pieplot3d.setForegroundAlpha(0.5F);
	pieplot3d.setNoDataMessage("无数据显示");
	
	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 %>">