项目需求：移动鼠标，在jfreechart生成的时间曲线图的节点上，显示数据。
具体过程：
资料1中，列出了用applet实现该功能的例子，
package gg; import java.awt.Color; import java.awt.Dimension; import java.text.SimpleDateFormat; import javax.swing.JPanel; import org.jfree.chart.*; import org.jfree.chart.axis.DateAxis; import org.jfree.chart.plot.XYPlot; import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer; import org.jfree.data.time.*; import org.jfree.data.xy.XYDataset; import org.jfree.ui.*; public class TimeSeriesDemo1 extends ApplicationFrame { public TimeSeriesDemo1(String s) { super(s); XYDataset xydataset = createDataset(); JFreeChart jfreechart = createChart(xydataset); ChartPanel chartpanel = new ChartPanel(jfreechart, false); chartpanel.setPreferredSize(new Dimension(500, 270)); chartpanel.setMouseZoomable(true, false); setContentPane(chartpanel); } private static JFreeChart createChart(XYDataset xydataset) { JFreeChart jfreechart = ChartFactory.createTimeSeriesChart("Legal & General Unit Trust Prices", "Date", "Price Per Unit", xydataset, true, true, true); jfreechart.setBackgroundPaint(Color.white); XYPlot xyplot = (XYPlot)jfreechart.getPlot(); xyplot.setBackgroundPaint(Color.lightGray); xyplot.setDomainGridlinePaint(Color.white); xyplot.setRangeGridlinePaint(Color.white); xyplot.setAxisOffset(new RectangleInsets(5D, 5D, 5D, 5D)); xyplot.setDomainCrosshairVisible(true); xyplot.setRangeCrosshairVisible(true); org.jfree.chart.renderer.xy.XYItemRenderer xyitemrenderer = xyplot.getRenderer(); if(xyitemrenderer instanceof XYLineAndShapeRenderer) { XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer)xyitemrenderer; xylineandshaperenderer.setBaseShapesVisible(true); xylineandshaperenderer.setBaseShapesFilled(true); } DateAxis dateaxis = (DateAxis)xyplot.getDomainAxis(); dateaxis.setDateFormatOverride(new SimpleDateFormat("MMM-yyyy")); return jfreechart; } private static XYDataset createDataset() { TimeSeries timeseries = new TimeSeries("L&G European Index Trust", org.jfree.data.time.Month.class); timeseries.add(new Month(2, 2001), 181.80000000000001D); timeseries.add(new Month(3, 2001), 167.30000000000001D); timeseries.add(new Month(4, 2001), 153.80000000000001D); timeseries.add(new Month(5, 2001), 167.59999999999999D); timeseries.add(new Month(6, 2001), 158.80000000000001D); timeseries.add(new Month(7, 2001), 148.30000000000001D); timeseries.add(new Month(8, 2001), 153.90000000000001D); timeseries.add(new Month(9, 2001), 142.69999999999999D); timeseries.add(new Month(10, 2001), 123.2D); timeseries.add(new Month(11, 2001), 131.80000000000001D); timeseries.add(new Month(12, 2001), 139.59999999999999D); timeseries.add(new Month(1, 2002), 142.90000000000001D); timeseries.add(new Month(2, 2002), 138.69999999999999D); timeseries.add(new Month(3, 2002), 137.30000000000001D); timeseries.add(new Month(4, 2002), 143.90000000000001D); timeseries.add(new Month(5, 2002), 139.80000000000001D); timeseries.add(new Month(6, 2002), 137D); timeseries.add(new Month(7, 2002), 132.80000000000001D); TimeSeries timeseries1 = new TimeSeries("L&G UK Index Trust", org.jfree.data.time.Month.class); timeseries1.add(new Month(2, 2001), 129.59999999999999D); timeseries1.add(new Month(3, 2001), 123.2D); timeseries1.add(new Month(4, 2001), 117.2D); timeseries1.add(new Month(5, 2001), 124.09999999999999D); timeseries1.add(new Month(6, 2001), 122.59999999999999D); timeseries1.add(new Month(7, 2001), 119.2D); timeseries1.add(new Month(8, 2001), 116.5D); timeseries1.add(new Month(9, 2001), 112.7D); timeseries1.add(new Month(10, 2001), 101.5D); timeseries1.add(new Month(11, 2001), 106.09999999999999D); timeseries1.add(new Month(12, 2001), 110.3D); timeseries1.add(new Month(1, 2002), 111.7D); timeseries1.add(new Month(2, 2002), 111D); timeseries1.add(new Month(3, 2002), 109.59999999999999D); timeseries1.add(new Month(4, 2002), 113.2D); timeseries1.add(new Month(5, 2002), 111.59999999999999D); timeseries1.add(new Month(6, 2002), 108.8D); timeseries1.add(new Month(7, 2002), 101.59999999999999D); TimeSeriesCollection timeseriescollection = new TimeSeriesCollection(); timeseriescollection.addSeries(timeseries); timeseriescollection.addSeries(timeseries1); return timeseriescollection; } public static JPanel createDemoPanel() { JFreeChart jfreechart = createChart(createDataset()); return new ChartPanel(jfreechart); } public static void main(String args[]) { TimeSeriesDemo1 timeseriesdemo1 = new TimeSeriesDemo1("Time Series Demo 1"); timeseriesdemo1.pack(); RefineryUtilities.centerFrameOnScreen(timeseriesdemo1); timeseriesdemo1.setVisible(true); } }
运行结果如下图，鼠标放到一数据点，显示出数值。
需求是在html页面上显示，怎样将applet转换到html上呢？
又找到资料2，关键是这句话：“JFreeChart所产生的原表如何得知滑鼠位置與這個區域的ToolTip、超連結的對應是什麼。事實上，我們還必須替這張圖表在網頁中建立區域對應表”。区域对应表（也称热区）怎么生成呢？在她给出了例子中，step5中，提到了生成的方法。
//Step 1 建立 Dataset 資料結構物件 HashMap datas = new HashMap(); datas.put("Java",new Long(721)); datas.put(".Net",new Long(543)); datas.put("PHP",new Long(374)); datas.put("C++",new Long(438)); datas.put("Others",new Long(424)); DefaultPieDataset dataSet = new DefaultPieDataset(); for(Iterator it = datas.keySet().iterator();it.hasNext();){ String technology = (String)it.next(); dataSet.setValue(technology, (Long)datas.get(technology)); } //Step 3 建立 Plot 物件 PiePlot plot = new PiePlot(dataSet); plot.setInsets(new RectangleInsets(5, 5, 5, 5)); plot.setURLGenerator(new StandardPieURLGenerator("DetailBarChart.jsp","section")); plot.setToolTipGenerator(new StandardPieItemLabelGenerator()); plot.setExplodePercent(0, 0.2); //Step 4 產生 JFreeChart 物件,並設定圖表底色 JFreeChart chart = new JFreeChart("My First Pie Chart", JFreeChart.DEFAULT_TITLE_FONT, plot, true); chart.setBackgroundPaint(Color.LIGHT_GRAY); //Step 5 輸出圖表,使用 ServletUtilities 將圖表輸出後由 DisplayChart Servlet 讀取 ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection()); String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info, session); PrintWriter writer = new PrintWriter(out); ChartUtilities.writeImageMap(writer, filename, info,false); writer.flush(); String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename; %><html> <body> <img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#<%= filename %>"> </body></html>
step1-step4，生成一个图表信息chart，只差将其显示出来。step5中，
1、首先调用ServletUtilities.saveChartAsPNG方法，将chart保存为一张png图的同时，把图表的绘制信息保存到info变量中。
2、将图片路径和图片的绘制信息输出
ChartUtilities.writeImageMap(writer, filename, info,false);
3、结束
问题：她这里是将生成的图片保存到某一路径下，
