首先将jfreechart1.0解压包的lib下面的jfreechart-1.0.0.jar、jcommon-1.0.0.jar 拷贝到TOMCAT_HOME/common/lib下面，其他的三个jar文件不能copy,否则tomcat5启动会出现异常。再将conf/web.xml里添加上:
<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>/servlet/DisplayChart</url-pattern>
</servlet-mapping>
以上的步骤基本上就成功了。要看看是否成功，请用下面的代码测试：
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<%@ page import="org.jfree.data.general.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"%>
<%@ page import="org.jfree.chart.encoders.SunPNGEncoderAdapter"%>
<%
DefaultPieDataset data = new DefaultPieDataset();
data.setValue("苹果",200);
data.setValue("梨子",300);
data.setValue("其他",400);
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("大家来投票,天下掉钱好不好?"); //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>Welcome to Jfreechart !</TITLE>
</HEAD>
<BODY>
<P ALIGN="CENTER">
<img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#<%= filename %>">
</P>
</BODY>
</HTML>
郑重声明，上面的一些东西都是根据网上的资料而来的！我只是做个笔记有助于以后的查询。