在b/s方式下使用jfreechart来生成统计图表

package gov.gwssi.tax.nspg.datadisposal;

import java.awt.Insets;
import java.awt.Image;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Locale;
import java.text.NumberFormat;
import javax.servlet.http.HttpSession;
import org.jfree.data.*;
import org.jfree.chart.*;
import org.jfree.chart.axis.*;
import org.jfree.chart.renderer.VerticalBarRenderer;
import org.jfree.chart.renderer.StandardXYItemRenderer;
import org.jfree.chart.plot.*;
import org.jfree.chart.entity.*;
import org.jfree.chart.tooltips.*;
import org.jfree.chart.urls.*;
import org.jfree.chart.servlet.*;
import java.awt.Font;

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: </p>
 * @author jagie
 * @version 1.0
 */

public class GSPieChart {
  public static void main(String[] args) {
    Long[] testData = {
        new Long(10), new Long(20), new Long(30), new Long(40)};
    generatePieChart(testData, "", null, new PrintWriter(System.out), 580, 250);
  }

  /**
   * 生成图像文件
   * @param datas Long[]数组
   * @param targetUrl 点饼形图上的扇形，定向到的url
   * @param session httpsession
   * @param pw PrintWriter
   * @param w 生成的图的宽度
   * @param h 生成的图的高度
   * @return 生成的图像文件的路径
   */

  public static String generatePieChart(Long[] datas, String targetUrl,
                                        HttpSession session, PrintWriter pw,
                                        int w, int h) {
    String filename = null;
    try {

      DefaultPieDataset data = new DefaultPieDataset();
      data.setValue("正常纳税人", datas[0]);
      data.setValue("异常纳税人", datas[1]);
      data.setValue("数据不全纳税人", datas[2]);
      data.setValue("未处理纳税人", datas[3]);

      //  Create the chart object
      Pie3DPlot plot = new Pie3DPlot(data);
      plot.setInsets(new Insets(0, 5, 5, 5));
      plot.setForegroundAlpha(0.6f);
      plot.setSectionLabelType(plot.NO_LABELS);

      plot.setURLGenerator(new StandardPieURLGenerator(targetUrl, "type"));
      plot.setToolTipGenerator(new StandardPieToolTipGenerator());
      JFreeChart chart = new JFreeChart("数据处理结果统计图",
                                        JFreeChart.DEFAULT_TITLE_FONT, plot, true);
      chart.setTitle(new TextTitle("数据处理结果统计图", new Font("黑体", Font.BOLD, 15)));
      StandardLegend sl = (StandardLegend) chart.getLegend();
      sl.setItemFont(new Font("黑体", Font.TRUETYPE_FONT, 12));

      chart.setBackgroundPaint(new java.awt.Color(254, 254, 141));

      //  因为jfreechart把生成的png文件保存在系统的临时文件夹中，你需要在适当的 
      //时候调用session.removeAttribute("JFreeChart_Deleter")，这样可以保证png文
      //件被删除掉

      ChartRenderingInfo info = new ChartRenderingInfo(new
          StandardEntityCollection());
      filename = ServletUtilities.saveChartAsPNG(chart, w, h, info, session);

      //  Write the image map to the PrintWriter
      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;
  }
}

<%

//以下部分为图象输出
String targetUrl="../servlet/gov.gwssi.tax.nspg.controlservlet.GSMainControlServlet?id="+sid;
Long[] datas={normals,new Long(totalAbnormal),dataLacks,notProcesses};
String filename=GSPieChart.generatePieChart(datas,targetUrl,session,new PrintWriter(out),580,250);
String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename;


%>
.......html代码................

<!-- pie chart -->
<table  width="580" border="0" cellspacing="0" cellpadding="0">
  <tr>
    <td> 
      <img src="<%= graphURL %>" width=580 height=250 border=0 
         usemap="#<%=filename %>">
    </td>
  </tr>
</table>

<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>