8.2 創建時序圖 · Java 開源項目中文文檔

## 8.2 創建時序圖 ### 8.2.1 概述時序圖表的確是一個使用XYDataset數據集的折線圖。不同點就是再主軸上X軸值顯示的是日期。本章講述的一個簡單應用如下圖8.1所示 ![](img/jfc48318.png) 圖8.1 一個簡單的時序圖表（參考：TimeSeriesDemo1.java）。上圖實例代碼參見類TimeSeriesDemo1.java。 ### 8.2.2 日期還是數字？創建序圖使用的數據集是XYDataset。接口不能有返回日期類型以外的方法。那么JFreeChart是如何創建時序圖表的呢？數據集返回的x值是基本的double類型，但這個值通過一種特殊的方式來進行轉譯成日期——該數是反映了一個從1970/1/1起計算的一個毫秒級值（譯碼過程使用java.util.Data類計算）。具體的軸類（DateAxis）將毫秒級數據轉化成日期，并作為需要返回該值，將數值作為主軸刻度顯示出來。 ### 8.2.3 數據集演示的本實例，數據使用的是一個TimeSeriesCollection對象（我們可以是任何XYDataset接口的實現）。代碼如下： ``` 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; } ``` 實例中，系列包含了每月的數據。盡管如此，仍然使用TimeSeries類來顯示間隔的時間值（年、日、小時等）。 ### 8.2.4 構建圖表使用ChartFactory類提供的便利方法createTimeSeriesChart()創建圖表，代碼如下： ``` 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? ); ``` 該方法構建了一個帶有標題、圖例、相應軸的區域和展示器的JFreeChart對象。使用的數據集見上一節內容。 ### 8.2.5 定制圖表圖表的大部分屬性使用了缺省的值進行初始化。當然，我們可以隨時修改這些屬性的設置來改變我們圖表的外觀展現。在本實例中，修改的幾個屬性如下： + 修改renderer，改變每個數據點顯示的系列形狀，數據點之間的折線除外。 + 主軸的數據格式進行格式化后顯示。修改renderer需要一下兩個步驟：獲得renderer引用和將renderer對象轉化成XYLineAndShapeRenderer類型。代碼如下： ``` XYItemRenderer xyitemrenderer = xyplot.getRenderer(); if (xyitemrenderer instanceof XYLineAndShapeRenderer) { XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer) xyitemrenderer; xylineandshaperenderer.setBaseShapesVisible(true); xylineandshaperenderer.setBaseShapesFilled(true); } ``` 最后，將格式化的數據傳給主軸，以改變顯示。代碼如下： ``` DateAxis dateaxis = (DateAxis) xyplot.getDomainAxis(); dateaxis.setDateFormatOverride(new SimpleDateFormat("MMM-yyyy")); ``` 當設置了Dataaxis時，系統將自動選擇一個DataTickUnit來顯示主軸刻度。但系統將使用上面我們格式化的數據來顯示，而不是系統默認的格式。 ### 8.2.6 全部代碼文檔的全部代碼如下： ``` /* 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; } } ```