8.2 创建时序图 · Java 开源项目中文文档

## 8.2 创建时序图 ### 8.2.1 概述时序图表的确是一个使用XYDataset数据集的折线图。不同点就是再主轴上X轴值显示的是日期。本章讲述的一个简单应用如下图8.1所示 ![](img/jfc48318.png) 图8.1 一个简单的时序图表（参考：TimeSeriesDemo1.java）。上图实例代码参见类TimeSeriesDemo1.java。 ### 8.2.2 日期还是数字？创建序图使用的数据集是XYDataset。接口不能有返回日期类型以外的方法。那么JFreeChart是如何创建时序图表的呢？数据集返回的x值是基本的double类型，但这个值通过一种特殊的方式来进行转译成日期——该数是反映了一个从1970/1/1起计算的一个毫秒级值（译码过程使用java.util.Data类计算）。具体的轴类（DateAxis）将毫秒级数据转化成日期，并作为需要返回该值，将数值作为主轴刻度显示出来。 ### 8.2.3 数据集演示的本实例，数据使用的是一个TimeSeriesCollection对象（我们可以是任何XYDataset接口的实现）。代码如下： ``` private static XYDataset createDataset() { TimeSeries timeseries = new TimeSeries( "L&G European Index Trust", (class$org$jfree$data$time$Month == null ? (class$org$jfree$data$time$Month = class$("org.jfree.data.time.Month")) : class$org$jfree$data$time$Month)); timeseries.add(new Month(2, 2001), 181.8); timeseries.add(new Month(3, 2001), 167.3); timeseries.add(new Month(4, 2001), 153.8); timeseries.add(new Month(5, 2001), 167.6); timeseries.add(new Month(6, 2001), 158.8); timeseries.add(new Month(7, 2001), 148.3); timeseries.add(new Month(8, 2001), 153.9); timeseries.add(new Month(9, 2001), 142.7); timeseries.add(new Month(10, 2001), 123.2); timeseries.add(new Month(11, 2001), 131.8); timeseries.add(new Month(12, 2001), 139.6); timeseries.add(new Month(1, 2002), 142.9); timeseries.add(new Month(2, 2002), 138.7); timeseries.add(new Month(3, 2002), 137.3); timeseries.add(new Month(4, 2002), 143.9); timeseries.add(new Month(5, 2002), 139.8); timeseries.add(new Month(6, 2002), 137.0); timeseries.add(new Month(7, 2002), 132.8); TimeSeries timeseries_0_ = new TimeSeries( "L&G UK Index Trust", (class$org$jfree$data$time$Month == null ? (class$org$jfree$data$time$Month = class$("org.jfree.data.time.Month")) : class$org$jfree$data$time$Month)); timeseries_0_.add(new Month(2, 2001), 129.6); timeseries_0_.add(new Month(3, 2001), 123.2); timeseries_0_.add(new Month(4, 2001), 117.2); timeseries_0_.add(new Month(5, 2001), 124.1); timeseries_0_.add(new Month(6, 2001), 122.6); timeseries_0_.add(new Month(7, 2001), 119.2); timeseries_0_.add(new Month(8, 2001), 116.5); timeseries_0_.add(new Month(9, 2001), 112.7); timeseries_0_.add(new Month(10, 2001), 101.5); timeseries_0_.add(new Month(11, 2001), 106.1); timeseries_0_.add(new Month(12, 2001), 110.3); timeseries_0_.add(new Month(1, 2002), 111.7); timeseries_0_.add(new Month(2, 2002), 111.0); timeseries_0_.add(new Month(3, 2002), 109.6); timeseries_0_.add(new Month(4, 2002), 113.2); timeseries_0_.add(new Month(5, 2002), 111.6); timeseries_0_.add(new Month(6, 2002), 108.8); timeseries_0_.add(new Month(7, 2002), 101.6); TimeSeriesCollection timeseriescollection = new TimeSeriesCollection(); timeseriescollection.addSeries(timeseries); timeseriescollection.addSeries(timeseries_0_); return timeseriescollection; } ``` 实例中，系列包含了每月的数据。尽管如此，仍然使用TimeSeries类来显示间隔的时间值（年、日、小时等）。 ### 8.2.4 构建图表使用ChartFactory类提供的便利方法createTimeSeriesChart()创建图表，代码如下： ``` JFreeChart jfreechart = ChartFactory.createTimeSeriesChart( "Legal & General Unit Trust Prices", // title "Date", // x-axis label "Price Per Unit", // y-axis label xydataset, // data true, // create legend? true, // generate tooltips? false // generate URLs? ); ``` 该方法构建了一个带有标题、图例、相应轴的区域和展示器的JFreeChart对象。使用的数据集见上一节内容。 ### 8.2.5 定制图表图表的大部分属性使用了缺省的值进行初始化。当然，我们可以随时修改这些属性的设置来改变我们图表的外观展现。在本实例中，修改的几个属性如下： + 修改renderer，改变每个数据点显示的系列形状，数据点之间的折线除外。 + 主轴的数据格式进行格式化后显示。修改renderer需要一下两个步骤：获得renderer引用和将renderer对象转化成XYLineAndShapeRenderer类型。代码如下： ``` XYItemRenderer xyitemrenderer = xyplot.getRenderer(); if (xyitemrenderer instanceof XYLineAndShapeRenderer) { XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer) xyitemrenderer; xylineandshaperenderer.setBaseShapesVisible(true); xylineandshaperenderer.setBaseShapesFilled(true); } ``` 最后，将格式化的数据传给主轴，以改变显示。代码如下： ``` DateAxis dateaxis = (DateAxis) xyplot.getDomainAxis(); dateaxis.setDateFormatOverride(new SimpleDateFormat("MMM-yyyy")); ``` 当设置了Dataaxis时，系统将自动选择一个DataTickUnit来显示主轴刻度。但系统将使用上面我们格式化的数据来显示，而不是系统默认的格式。 ### 8.2.6 全部代码文档的全部代码如下： ``` /* TimeSeriesDemo1 - Decompiled by JODE * Visit http://jode.sourceforge.net/ */ package demo; import java.awt.Color; import java.awt.Dimension; import java.text.SimpleDateFormat; import javax.swing.JPanel; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartPanel; import org.jfree.chart.JFreeChart; import org.jfree.chart.axis.DateAxis; import org.jfree.chart.plot.XYPlot; import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer; import org.jfree.data.time.Month; import org.jfree.data.time.TimeSeries; import org.jfree.data.time.TimeSeriesCollection; import org.jfree.data.xy.XYDataset; import org.jfree.ui.ApplicationFrame; import org.jfree.ui.RectangleInsets; import org.jfree.ui.RefineryUtilities; public class TimeSeriesDemo1 extends ApplicationFrame { private static final long serialVersionUID = -5412286370956646368L; /* synthetic */ static Class class$org$jfree$data$time$Month; public TimeSeriesDemo1(String string) { super(string); XYDataset xydataset = createDataset(); JFreeChart jfreechart = createChart(xydataset); ChartPanel chartpanel = new ChartPanel(jfreechart, false); chartpanel.setPreferredSize(new Dimension(500, 270)); chartpanel.setMouseZoomable(true, false); setContentPane(chartpanel); } private static JFreeChart createChart(XYDataset xydataset) { JFreeChart jfreechart = ChartFactory.createTimeSeriesChart( "Legal & General Unit Trust Prices", // title "Date", // x-axis label "Price Per Unit", // y-axis label xydataset, // data true, // create legend? true, // generate tooltips? false // generate URLs? ); jfreechart.setBackgroundPaint(Color.white); XYPlot xyplot = (XYPlot) jfreechart.getPlot(); xyplot.setBackgroundPaint(Color.lightGray); xyplot.setDomainGridlinePaint(Color.white); xyplot.setRangeGridlinePaint(Color.white); xyplot.setAxisOffset(new RectangleInsets(5.0, 5.0, 5.0, 5.0)); xyplot.setDomainCrosshairVisible(true); xyplot.setRangeCrosshairVisible(true); org.jfree.chart.renderer.xy.XYItemRenderer xyitemrenderer = xyplot .getRenderer(); if (xyitemrenderer instanceof XYLineAndShapeRenderer) { XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer) xyitemrenderer; xylineandshaperenderer.setBaseShapesVisible(true); xylineandshaperenderer.setBaseShapesFilled(true); } DateAxis dateaxis = (DateAxis) xyplot.getDomainAxis(); dateaxis.setDateFormatOverride(new SimpleDateFormat("MMM-yyyy")); return jfreechart; } private static XYDataset createDataset() { TimeSeries timeseries = new TimeSeries( "L&G European Index Trust", (class$org$jfree$data$time$Month == null ? (class$org$jfree$data$time$Month = class$("org.jfree.data.time.Month")) : class$org$jfree$data$time$Month)); timeseries.add(new Month(2, 2001), 181.8); timeseries.add(new Month(3, 2001), 167.3); timeseries.add(new Month(4, 2001), 153.8); timeseries.add(new Month(5, 2001), 167.6); timeseries.add(new Month(6, 2001), 158.8); timeseries.add(new Month(7, 2001), 148.3); timeseries.add(new Month(8, 2001), 153.9); timeseries.add(new Month(9, 2001), 142.7); timeseries.add(new Month(10, 2001), 123.2); timeseries.add(new Month(11, 2001), 131.8); timeseries.add(new Month(12, 2001), 139.6); timeseries.add(new Month(1, 2002), 142.9); timeseries.add(new Month(2, 2002), 138.7); timeseries.add(new Month(3, 2002), 137.3); timeseries.add(new Month(4, 2002), 143.9); timeseries.add(new Month(5, 2002), 139.8); timeseries.add(new Month(6, 2002), 137.0); timeseries.add(new Month(7, 2002), 132.8); TimeSeries timeseries_0_ = new TimeSeries( "L&G UK Index Trust", (class$org$jfree$data$time$Month == null ? (class$org$jfree$data$time$Month = class$("org.jfree.data.time.Month")) : class$org$jfree$data$time$Month)); timeseries_0_.add(new Month(2, 2001), 129.6); timeseries_0_.add(new Month(3, 2001), 123.2); timeseries_0_.add(new Month(4, 2001), 117.2); timeseries_0_.add(new Month(5, 2001), 124.1); timeseries_0_.add(new Month(6, 2001), 122.6); timeseries_0_.add(new Month(7, 2001), 119.2); timeseries_0_.add(new Month(8, 2001), 116.5); timeseries_0_.add(new Month(9, 2001), 112.7); timeseries_0_.add(new Month(10, 2001), 101.5); timeseries_0_.add(new Month(11, 2001), 106.1); timeseries_0_.add(new Month(12, 2001), 110.3); timeseries_0_.add(new Month(1, 2002), 111.7); timeseries_0_.add(new Month(2, 2002), 111.0); timeseries_0_.add(new Month(3, 2002), 109.6); timeseries_0_.add(new Month(4, 2002), 113.2); timeseries_0_.add(new Month(5, 2002), 111.6); timeseries_0_.add(new Month(6, 2002), 108.8); timeseries_0_.add(new Month(7, 2002), 101.6); TimeSeriesCollection timeseriescollection = new TimeSeriesCollection(); timeseriescollection.addSeries(timeseries); timeseriescollection.addSeries(timeseries_0_); return timeseriescollection; } public static JPanel createDemoPanel() { JFreeChart jfreechart = createChart(createDataset()); return new ChartPanel(jfreechart); } public static void main$(String[] strings) { TimeSeriesDemo1 timeseriesdemo1 = new TimeSeriesDemo1( "Time Series Demo 1"); timeseriesdemo1.pack(); RefineryUtilities.centerFrameOnScreen(timeseriesdemo1); timeseriesdemo1.setVisible(true); } public static void main(String[] args) { main$(args); } /* synthetic */ static Class class$(String string) { Class var_class; try { var_class = Class.forName(string); } catch (ClassNotFoundException classnotfoundexception) { throw new NoClassDefFoundError(classnotfoundexception.getMessage()); } return var_class; } } ```