jfreechart在jsp中画图方式

这个问题一直困扰我好久，今天算是稍微找到一点解决思路了，在网上搜了好多列子，大部分的都是用servlet来实现画图，偶然找到一个列子用的是org.jfree.chart.servlet.ServletUtilities,来解决图片从后台传到前台的方法，下面是源码。

1.在MyEclipse中创建一个名为jfreechart的Web工程。将下载的JFreeChart1.0.6下lib目录下的jar包拷贝到WebRoot/WEB-INF/lib目录下。另外还需要在web.xml文件中增加如下配置：

    <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>

2.在WebRoot目录下建立bar目录，用来存放柱状图的各个例子。首先在该目录下建立一个sample1.jsp文件，让我们来看一个简单的柱状图的例子，修改后的sample1.jsp的内容如下所示：

<%@ page contentType="text/html;charset=GBK"%>
<%@ page import="org.jfree.chart.ChartFactory,
        org.jfree.chart.JFreeChart,
        org.jfree.chart.plot.PlotOrientation,
        org.jfree.chart.servlet.ServletUtilities,
        org.jfree.data.category.DefaultCategoryDataset,
        java.awt.Font,
        org.jfree.chart.ChartFrame,
        org.jfree.chart.StandardChartTheme,
        org.jfree.chart.axis.CategoryAxis,
        org.jfree.chart.labels.StandardCategoryItemLabelGenerator,
        org.jfree.chart.plot.CategoryPlot,
        org.jfree.chart.renderer.category.BarRenderer,
        org.jfree.data.category.CategoryDataset,
        java.io.FileOutputStream,
        java.io.IOException,
        java.io.PrintWriter,
        org.jfree.chart.ChartUtilities,
        org.jfree.chart.axis.ValueAxis,
        org.jfree.chart.title.LegendTitle,
        org.jfree.chart.title.TextTitle"
%>
<%
    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    dataset.addValue(610, "广州", "猪肉");
    dataset.addValue(220, "广州", "牛肉");
    dataset.addValue(530, "广州", "鸡肉");
    dataset.addValue(340, "广州", "鱼肉");

    JFreeChart mBarChart = ChartFactory.createBarChart3D("肉类销量统计图",
    "肉类",
    "销量",
    dataset,
    PlotOrientation.VERTICAL,
    false,
    false,
    false);    

                //图表标题设置
            TextTitle mTextTitle = mBarChart.getTitle();
            mTextTitle.setFont(new Font("黑体", Font.BOLD, 20));
            //mBarChart.setTitle(new TextTitle("学校人员分布图",new Font("黑体", Font.BOLD, 20)));
            //图表图例设置
            LegendTitle mLegend = mBarChart.getLegend();
            if(mLegend != null)
                mLegend.setItemFont(new Font("宋体", Font.CENTER_BASELINE, 15));
            //mBarChart.getLegend().setItemFont(new Font("宋体", Font.CENTER_BASELINE, 15));
            //设置柱状图轴
            CategoryPlot mPlot = (CategoryPlot)mBarChart.getPlot();  

            //x轴
            CategoryAxis mDomainAxis = mPlot.getDomainAxis();
            //设置x轴标题的字体
            mDomainAxis.setLabelFont(new Font("宋体", Font.PLAIN, 15));
            //设置x轴坐标字体
            mDomainAxis.setTickLabelFont(new Font("宋体", Font.PLAIN, 15));
            //y轴
            ValueAxis mValueAxis = mPlot.getRangeAxis();
            //设置y轴标题字体
            mValueAxis.setLabelFont(new Font("宋体", Font.PLAIN, 15));
            //设置y轴坐标字体
            mValueAxis.setTickLabelFont(new Font("宋体", Font.PLAIN, 15));
            //柱体显示数值
            BarRenderer mRenderer= new BarRenderer();
            mRenderer.setItemLabelGenerator(new StandardCategoryItemLabelGenerator());
            mRenderer.setItemLabelFont(new Font("宋体", Font.PLAIN, 10));
            mRenderer.setItemLabelsVisible(true);
            mPlot.setRenderer(mRenderer);  

            String filename = ServletUtilities.saveChartAsPNG(mBarChart, 800, 400, null, session);
            String graphURL = request.getContextPath() + "/DisplayChart?filename=" + filename;
%>
<img src="<%= graphURL %>" width=800 height=400 border=0 usemap="#<%= filename %>">

浏览器端输入http://127.0.0.1:8080/jfreechart/sample1.jsp即可看到输出的图片。