java 显示柱状图报错

package wsy.servlet;
import java.awt.Color;

import java.awt.Font;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.jfree.chart.ChartFactory;

import org.jfree.chart.ChartUtilities;

import org.jfree.chart.JFreeChart;

import org.jfree.chart.axis.CategoryAxis;

import org.jfree.chart.axis.NumberAxis;

import org.jfree.chart.plot.CategoryPlot;

import org.jfree.chart.plot.PlotOrientation;

import org.jfree.chart.renderer.category.BarRenderer;

import org.jfree.chart.title.TextTitle;

import org.jfree.data.category.DefaultCategoryDataset;

/**

• 柱状分布统计图
• @说明
  
• @author cuisuqiang
• @version 1.0

• @since
  /
  
  @SuppressWarnings("serial")
  
  public class ParagraphsServlet extends HttpServlet {
  
  protected void service(HttpServletRequest request,
  
  HttpServletResponse response) throws ServletException, IOException {
  
  response.setContentType("text/html");
  
  DefaultCategoryDataset dataTime = new DefaultCategoryDataset();
  
  // 这是一组数据
  
  dataTime.addValue(52, "0-6", "2010-1-1");
  
  dataTime.addValue(86, "6-12", "2010-1-1");
  
  dataTime.addValue(126, "12-18", "2010-1-1");
  
  dataTime.addValue(42, "18-24", "2010-1-1");
  
  // 这是一组数据
  
  dataTime.addValue(452, "0-6", "2010-1-2");
  
  dataTime.addValue(96, "6-12", "2010-1-2");
  
  dataTime.addValue(254, "12-18", "2010-1-2");
  
  dataTime.addValue(126, "18-24", "2010-1-2");
  
  // 这是一组数据
  
  dataTime.addValue(256, "0-6", "2010-1-3");
  
  dataTime.addValue(86, "6-12", "2010-1-3");
  
  dataTime.addValue(365, "12-18", "2010-1-3");
  
  dataTime.addValue(24, "18-24", "2010-1-3");
  
  try {
  
  DefaultCategoryDataset data = dataTime;
  
  // 使用ChartFactory创建3D柱状图，不想使用3D，直接使用createBarChart
  
  JFreeChart chart = ChartFactory.createBarChart3D(
  
  "网站时间段访问量统计",
  
  "时间",
  
  "访问量",
  
  data,
  
  PlotOrientation.VERTICAL,
  
  true,
  
  false,
  
  false
  
  );
  
  // 设置整个图片的背景色
  
  chart.setBackgroundPaint(Color.PINK);
  
  // 设置图片有边框
  
  chart.setBorderVisible(true);
  
  Font kfont = new Font("宋体", Font.PLAIN, 12); // 底部
  
  Font titleFont = new Font("宋体", Font.BOLD, 25); // 图片标题
  
  // 图片标题
  
  chart.setTitle(new TextTitle(chart.getTitle().getText(), titleFont));
  
  // 底部
  
  chart.getLegend().setItemFont(kfont);
  
  // 得到坐标设置字体解决乱码
  
  CategoryPlot categoryplot = (CategoryPlot) chart.getPlot();
  
  categoryplot.setDomainGridlinesVisible(true);
  
  categoryplot.setRangeCrosshairVisible(true);
  
  categoryplot.setRangeCrosshairPaint(Color.blue);
  
  NumberAxis numberaxis = (NumberAxis) categoryplot.getRangeAxis();
  
  numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
  
  BarRenderer barrenderer = (BarRenderer) categoryplot.getRenderer();
  
  barrenderer.setBaseItemLabelFont(new Font("宋体", Font.PLAIN, 12));
  
  barrenderer.setSeriesItemLabelFont(1, new Font("宋体", Font.PLAIN, 12));
  
  CategoryAxis domainAxis = categoryplot.getDomainAxis();
  
  /------设置X轴坐标上的文字-----------*/
  
  domainAxis.setTickLabelFont(new Font("sans-serif", Font.PLAIN, 11));
  
  /*------设置X轴的标题文字------------*/
  
  domainAxis.setLabelFont(new Font("宋体", Font.PLAIN, 12));
  
  /*------设置Y轴坐标上的文字-----------*/
  
  numberaxis.setTickLabelFont(new Font("sans-serif", Font.PLAIN, 12));
  
  /*------设置Y轴的标题文字------------*/
  
  numberaxis.setLabelFont(new Font("宋体", Font.PLAIN, 12));
  
  /*------这句代码解决了底部汉字乱码的问题-----------*/
  
  chart.getLegend().setItemFont(new Font("宋体", Font.PLAIN, 12));
  
  ChartUtilities.writeChartAsJPEG(response.getOutputStream(), 1f, chart,600,300, null);

  } catch (Exception es) {  
      es.printStackTrace();  
  }  
  

  }
  
  }

请大师帮忙提点下

后台点debug 调试一下