作者:ronghao100
在使用cewolf 之前,首先来熟悉一下jFreeChart 。这里分三部分来介绍 jFreeChart 。第一部分介绍jFreeChart产生
图形的流程及相关的重要的类;第二部分介绍四种常用的报表图(饼图、柱状图、折线图、时间序列图);第三部分
介绍在图形中增加Item Lable 。 
jFreeChart 的版本是jfreechart-1.0.0-pre2(1)
cewolf 的最新版本是cewolf-0.12.0

一、jFreeChart产生图形的流程
  1. 创建一个数据源(dataset)来包含将要在图形中显示的数据?
  2. 创建一个 JFreeChart 对象来代表要显示的图形
  3. 把图形输出
   重要的类和接口:
   org.jfree.data.general.Dataset  所有数据源类都要实现的接口
   org.jfree.chart.ChartFactory    由它来产生 JFreeChart 对象
   org.jfree.chart.JFreeChart    所有对图形的调整都是通过它噢!!
   org.jfree.chart.plot.Plot    通过JFreeChart 对象获得它,然后再通过它对图形外部部分(例:坐标轴)调整
                                注意:它有很多子类,一般都下嗍造型到它的子类!
   org.jfree.chart.renderer.AbstractRenderer     通过JFreeChart 对象获得它,然后再通过它对图形内部部分
                                                (例:折线的类型)调整。同样,针对不同类型的报表图,它有
                                                着不同的子类实现!在下面我们简称它为 Renderer
   下面我们结合不同类型的图形来具体分析这个流程。
   
二、饼图
   饼图的dataset 一般是用PieDataset 接口,具体实现类是 DefaultPieDataset
   1、创建一个数据源(dataset):
    
private static PieDataset createDataset()
    
{
        DefaultPieDataset defaultpiedataset 
= new DefaultPieDataset(); //注意是DefaultPieDataset!!
        defaultpiedataset.setValue("One"new Double(43.200000000000003D));
        defaultpiedataset.setValue(
"Two"new Double(10D));
        defaultpiedataset.setValue(
"Three"new Double(27.5D));
        defaultpiedataset.setValue(
"Four"new Double(17.5D));
        
return defaultpiedataset;
    }
 
   
  2、由ChartFactory  产生 JFreeChart 对象

 private static JFreeChart createChart(PieDataset piedataset)
    
{
        JFreeChart jfreechart 
= ChartFactory.createPieChart("Pie Chart Demo 1",  //图形标题名称
                                                              piedataset,   // dataset
                                                              true,      // legend?
                                                              true,     // tooltips?
                                                              false);  //URLs?
        PiePlot pieplot = (PiePlot)jfreechart.getPlot();  //通过JFreeChart 对象获得 plot:PiePlot!!
        pieplot.setNoDataMessage("No data available");    // 没有数据的时候显示的内容
        return jfreechart;
    }
 
   
    一些重要的方法:
    pieplot.setExplodePercent(0,0.3D) //把Lable 为"One" 的那一块”挖“出来30%    
   3、输出略  
   
三、柱状图
   柱状图的dataset 一般是用CatagoryDataset接口(具体实现类是DefaultCategoryDataset),也会用 IntervalXYDataset 
   接口
   1、创建一个数据源(dataset):
 private static CategoryDataset createDataset()
    
{
        String series1 
= "First";
        String series2 
= "Second";
        String series3 
= "Third";
        String category1 
= "Category 1";
        String category2 
= "Category 2";
        String category3 
= "Category 3";
        String category4 
= "Category 4";
        String category5 
= "Category 5";
        DefaultCategoryDataset defaultcategorydataset 
= new DefaultCategoryDataset();
        defaultcategorydataset.addValue(
1.0D, series1, category1);
        defaultcategorydataset.addValue(4D, series1, category2);
        defaultcategorydataset.addValue(3D, series1, category3);
        defaultcategorydataset.addValue(5D, series1, category4);
        defaultcategorydataset.addValue(5D, series1, category5);
        
        defaultcategorydataset.addValue(5D, series2, category1);
        defaultcategorydataset.addValue(7D, series2, category2);
        defaultcategorydataset.addValue(6D, series2, category3);
        defaultcategorydataset.addValue(8D, series2, category4);
        defaultcategorydataset.addValue(4D, series2, category5);
        
        defaultcategorydataset.addValue(4D, series3, category1);
        defaultcategorydataset.addValue(3D, series3, category2);
        defaultcategorydataset.addValue(2D, series3, category3);
        defaultcategorydataset.addValue(3D, series3, category4);
        defaultcategorydataset.addValue(6D, series3, category5);
        
return defaultcategorydataset;
    }


      2、由ChartFactory  产生 JFreeChart 对象    
  
  private static JFreeChart createChart(CategoryDataset categorydataset)
    
{
        JFreeChart jfreechart 
= ChartFactory.createBarChart("Bar Chart Demo"//图形标题名称
                                                            "Category",//domain 轴 Lable 
                                                                         这里先简单理解为横坐标Lable好了
                                                            
"Value"//range 轴 Lable
                                                                       这里也先简单理解为纵坐标Lable好了
                                                            categorydataset, 
//  dataset
                                                            PlotOrientation.VERTICAL, //垂直显示
                                                            true// legend?
                                                            true,  // tooltips?
                                                            false); //URLs?
        jfreechart.setBackgroundPaint(Color.white);   //设定背景色为白色
        CategoryPlot categoryplot = jfreechart.getCategoryPlot(); //获得 plot:CategoryPlot!!
        categoryplot.setBackgroundPaint(Color.lightGray); //设定图表数据显示部分背景色
        categoryplot.setDomainGridlinePaint(Color.white); //横坐标网格线白色
        categoryplot.setDomainGridlinesVisible(true); //可见
        categoryplot.setRangeGridlinePaint(Color.white); //纵坐标网格线白色
        
//下面两行使纵坐标的最小单位格为整数
        NumberAxis numberaxis = (NumberAxis)categoryplot.getRangeAxis();
        numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
        BarRenderer barrenderer 
= (BarRenderer)categoryplot.getRenderer(); //获得renderer 注意这里是下嗍造型
                                                                             到BarRenderer!!
        barrenderer.setDrawBarOutline(
false); // Bar的外轮廓线不画
        GradientPaint gradientpaint = new GradientPaint(0.0F0.0F, Color.blue, 
        
0.0F0.0Fnew Color(0064));   //设定特定颜色
        GradientPaint gradientpaint1 = new GradientPaint(0.0F0.0F, Color.green, 
        
0.0F0.0Fnew Color(0640));
        GradientPaint gradientpaint2 
= new GradientPaint(0.0F0.0F, Color.red,
        
0.0F0.0Fnew Color(6400));
        barrenderer.setSeriesPaint(
0, gradientpaint); //给series1 Bar设定上面定义的颜色
        barrenderer.setSeriesPaint(1, gradientpaint1); //给series2 Bar 设定上面定义的颜色
        barrenderer.setSeriesPaint(2, gradientpaint2); //给series3 Bar 设定上面定义的颜色
        CategoryAxis categoryaxis = categoryplot.getDomainAxis();  //横轴上的 Lable 45度倾斜
        categoryaxis.setCategoryLabelPositions(CategoryLabelPositions.UP_45);        
        
return jfreechart;
    }
  
    一些重要的方法:(增加一块标记)
        IntervalMarker intervalmarker = new IntervalMarker(4.5D, 7.5D);
        intervalmarker.setLabel("Target Range");
        intervalmarker.setLabelFont(new Font("SansSerif", 2, 11));
        intervalmarker.setLabelAnchor(RectangleAnchor.LEFT);
        intervalmarker.setLabelTextAnchor(TextAnchor.CENTER_LEFT);
        intervalmarker.setPaint(new Color(222, 222, 255, 128));
        categoryplot.addRangeMarker(intervalmarker, Layer.BACKGROUND);    
        
四、折线图
   折线图的dataset 两种CatagoryDataset接口(具体实现类是DefaultCategoryDataset),XYDataset 接口 
   1、CatagoryDataset接口:         
   A、创建一个数据源(dataset): 
    
private static CategoryDataset createDataset()
    
{
        String series1 
= "First";
        String series2 
= "Second";
        String series3 
= "Third";
        String type1 
= "Type 1";
        String type2 
= "Type 2";
        String type3 
= "Type 3";
        String type4 
= "Type 4";
        String type5 
= "Type 5";
        String type6 
= "Type 6";
        String type7 
= "Type 7";
        String type8 
= "Type 8";
        DefaultCategoryDataset defaultcategorydataset 
= new DefaultCategoryDataset();
        defaultcategorydataset.addValue(
1.0D, series1, type1);
        defaultcategorydataset.addValue(4D, series1, type2);
        defaultcategorydataset.addValue(3D, series1, type3);
        defaultcategorydataset.addValue(5D, series1, type4);
        defaultcategorydataset.addValue(5D, series1, type5);
        defaultcategorydataset.addValue(7D, series1, type6);
        defaultcategorydataset.addValue(7D, series1, type7);
        defaultcategorydataset.addValue(8D, series1, type8);
        
        defaultcategorydataset.addValue(5D, series2, type1);
        defaultcategorydataset.addValue(7D, series2, type2);
        defaultcategorydataset.addValue(6D, series2, type3);
        defaultcategorydataset.addValue(8D, series2, type4);
        defaultcategorydataset.addValue(4D, series2, type5);
        defaultcategorydataset.addValue(4D, series2, type6);
        defaultcategorydataset.addValue(2D, series2, type7);
        defaultcategorydataset.addValue(
1.0D, series2, type8);
        
        defaultcategorydataset.addValue(4D, series3, type1);
        defaultcategorydataset.addValue(3D, series3, type2);
        defaultcategorydataset.addValue(2D, series3, type3);
        defaultcategorydataset.addValue(3D, series3, type4);
        defaultcategorydataset.addValue(6D, series3, type5);
        defaultcategorydataset.addValue(3D, series3, type6);
        defaultcategorydataset.addValue(4D, series3, type7);
        defaultcategorydataset.addValue(3D, series3, type8);
        
return defaultcategorydataset;
    }
 
   B、由ChartFactory  产生 JFreeChart 对象     (与上面重复的部分就不再注释)
    
private static JFreeChart createChart(CategoryDataset categorydataset)
    
{
        JFreeChart jfreechart 
= ChartFactory.createLineChart("Line Chart Demo 1"
                                                             
"Type"
                                                             
"Value"
                                                             categorydataset, 
                                                             PlotOrientation.VERTICAL, 
                                                             
true
                                                             
true
                                                             
false);
        jfreechart.setBackgroundPaint(Color.white);
        CategoryPlot categoryplot 
= (CategoryPlot)jfreechart.getPlot();
        categoryplot.setBackgroundPaint(Color.lightGray);
        categoryplot.setRangeGridlinePaint(Color.white);
        NumberAxis numberaxis 
= (NumberAxis)categoryplot.getRangeAxis();
        numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
        numberaxis.setAutoRangeIncludesZero(
true);
        
//获得renderer 注意这里是下嗍造型到lineandshaperenderer!!
        LineAndShapeRenderer lineandshaperenderer = (LineAndShapeRenderer)categoryplot.getRenderer();
        lineandshaperenderer.setShapesVisible(
true); //series 点(即数据点)可见
        lineandshaperenderer.setSeriesStroke(0new BasicStroke(2.0F111.0Fnew float[] {
            10F, 6F
        }
0.0F)); //定义series为"First"的(即series1)点之间的连线 ,这里是虚线,默认是直线
        lineandshaperenderer.setSeriesStroke(1new BasicStroke(2.0F111.0Fnew float[] {
            6F, 6F
        }
0.0F)); //定义series为"Second"的(即series2)点之间的连线
        lineandshaperenderer.setSeriesStroke(2new BasicStroke(2.0F111.0Fnew float[] {
            
2.0F, 6F
        }
0.0F)); //定义series为"Third"的(即series3)点之间的连线
        return jfreechart;
    }
 
        
一些重要的方法:
       
 lineandshaperenderer.setLineVisible(true)  //series 点(即数据点)间有连线可见
   2、XYDataset 接口:
   A、创建一个数据源(dataset):
    
private static XYDataset createDataset()
    
{
        XYSeries xyseries 
= new XYSeries("First"); //先产生XYSeries 对象
        xyseries.add(1.0D1.0D);
        xyseries.add(2D, 4D);
        xyseries.add(3D, 3D);
        xyseries.add(4D, 5D);
        xyseries.add(5D, 5D);
        xyseries.add(6D, 7D);
        xyseries.add(7D, 7D);
        xyseries.add(8D, 8D);
        
        XYSeries xyseries1 
= new XYSeries("Second");
        xyseries1.add(
1.0D, 5D);
        xyseries1.add(2D, 7D);
        xyseries1.add(3D, 6D);
        xyseries1.add(4D, 8D);
        xyseries1.add(5D, 4D);
        xyseries1.add(6D, 4D);
        xyseries1.add(7D, 2D);
        xyseries1.add(8D, 
1.0D);
        
        XYSeries xyseries2 
= new XYSeries("Third");
        xyseries2.add(3D, 4D);
        xyseries2.add(4D, 3D);
        xyseries2.add(5D, 2D);
        xyseries2.add(6D, 3D);
        xyseries2.add(7D, 6D);
        xyseries2.add(8D, 3D);
        xyseries2.add(9D, 4D);
        xyseries2.add(10D, 3D);
        
        XYSeriesCollection xyseriescollection 
= new XYSeriesCollection(); //再用XYSeriesCollection添加入XYSeries 对象
        xyseriescollection.addSeries(xyseries);
        xyseriescollection.addSeries(xyseries1);
        xyseriescollection.addSeries(xyseries2);
        
return xyseriescollection;
    }

   B、由ChartFactory  产生 JFreeChart 对象 
   
 private static JFreeChart createChart(XYDataset xydataset)
    
{
        JFreeChart jfreechart 
= ChartFactory.createXYLineChart("Line Chart Demo 2"
                                                               
"X"
                                                               
"Y"
                                                               xydataset, 
                                                               PlotOrientation.VERTICAL, 
                                                               
true
                                                               
true
                                                               
false);
        jfreechart.setBackgroundPaint(Color.white);
        XYPlot xyplot 
= (XYPlot)jfreechart.getPlot(); //获得 plot:XYPlot!!
        xyplot.setBackgroundPaint(Color.lightGray); //设定图表数据显示部分背景色
        xyplot.setAxisOffset(new RectangleInsets(5D, 5D, 5D, 5D)); //设定坐标轴与图表数据显示部分距离
        xyplot.setDomainGridlinePaint(Color.white); //网格线颜色
        xyplot.setRangeGridlinePaint(Color.white);
        
//获得 renderer 注意这里是XYLineAndShapeRenderer !!
        XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer)xyplot.getRenderer();
        xylineandshaperenderer.setShapesVisible(
true); //数据点可见
        xylineandshaperenderer.setShapesFilled(true); //数据点被填充即不是空心点
        NumberAxis numberaxis = (NumberAxis)xyplot.getRangeAxis();
        numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
        
return jfreechart;
    }
                      
   一些重要的方法:
        XYLineAndShapeRenderer xylineandshaperenderer = new XYLineAndShapeRenderer();
        xylineandshaperenderer.setSeriesLinesVisible(0, false); //第一个XYSeries数据点间连线不可见
        xylineandshaperenderer.setSeriesShapesVisible(1, false); //第二个XYSeries数据点不可见
        xyplot.setRenderer(xylineandshaperenderer);   
        
五、时间序列图
    时间序列图和折线图很相似,不同的是它在 domain轴的数据是时间而不是数字。 时间序列图的dataset 是
    XYDataset 接口,具体实现类是TimeSeriesCollection ,和上面类似,有TimeSeries 对象,它被添加入
    TimeSeriesCollection 。                                                                               
  1、创建一个数据源(dataset):
    
private static XYDataset createDataset()
    
{
        TimeSeries timeseries 
= new TimeSeries("L&G European Index Trust",Month.class);
        timeseries.add(
new Month(22001), 181.8D);//这里用的是Month.class,同样还有Day.class Year.class 等等
        timeseries.add(new Month(32001), 167.3D);
        timeseries.add(
new Month(42001), 153.8D);
        timeseries.add(
new Month(52001), 167.6D);
        timeseries.add(
new Month(62001), 158.8D);
        timeseries.add(
new Month(72001), 148.3D);
        timeseries.add(
new Month(82001), 153.9D);
        timeseries.add(
new Month(92001), 142.7D);
        timeseries.add(
new Month(102001), 123.2D);
        timeseries.add(
new Month(112001), 131.8D);
        timeseries.add(
new Month(122001), 139.6D);
        timeseries.add(
new Month(12002), 142.9D);
        timeseries.add(
new Month(22002), 138.7D);
        timeseries.add(
new Month(32002), 137.3D);
        timeseries.add(
new Month(42002), 143.9D);
        timeseries.add(
new Month(52002), 139.8D);
        timeseries.add(
new Month(62002), 137D);
        timeseries.add(
new Month(72002), 132.8D);
        
        TimeSeries timeseries1 
= new TimeSeries("L&G UK Index Trust",Month.class);
        timeseries1.add(
new Month(22001), 129.6D);
        timeseries1.add(
new Month(32001), 123.2D);
        timeseries1.add(
new Month(42001), 117.2D);
        timeseries1.add(
new Month(52001), 124.1D);
        timeseries1.add(
new Month(62001), 122.6D);
        timeseries1.add(
new Month(72001), 119.2D);
        timeseries1.add(
new Month(82001), 116.5D);
        timeseries1.add(
new Month(92001), 112.7D);
        timeseries1.add(
new Month(102001), 101.5D);
        timeseries1.add(
new Month(112001), 106.1D);
        timeseries1.add(
new Month(122001), 110.3D);
        timeseries1.add(
new Month(12002), 111.7D);
        timeseries1.add(
new Month(22002), 111D);
        timeseries1.add(
new Month(32002), 109.6D);
        timeseries1.add(
new Month(42002), 113.2D);
        timeseries1.add(
new Month(52002), 111.6D);
        timeseries1.add(
new Month(62002), 108.8D);
        timeseries1.add(
new Month(72002), 101.6D);
        TimeSeriesCollection timeseriescollection 
= new TimeSeriesCollection();
        timeseriescollection.addSeries(timeseries);
        timeseriescollection.addSeries(timeseries1);
        timeseriescollection.setDomainIsPointsInTime(
true); //domain轴上的刻度点代表的是时间点而不是时间段
        return timeseriescollection;
    }

   2、由ChartFactory  产生 JFreeChart 对象 
   
 private static JFreeChart createChart(XYDataset xydataset)
    
{
        JFreeChart jfreechart 
= ChartFactory.createTimeSeriesChart("Legal & General Unit Trust Prices"
                                                                   
"Date"
                                                                   
"Price Per Unit"
                                                                   xydataset, 
                                                                   
true
                                                                   
true
                                                                   
false);
        jfreechart.setBackgroundPaint(Color.white);
        XYPlot xyplot 
= (XYPlot)jfreechart.getPlot(); //获得 plot : XYPlot!!
        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.setDefaultShapesVisible(
true); //数据点可见
            xylineandshaperenderer.setDefaultShapesFilled(true);  //数据点是实心点
        }

        DateAxis dateaxis 
= (DateAxis)xyplot.getDomainAxis(); //对domain 轴上日期显示格式定义
        dateaxis.setDateFormatOverride(new SimpleDateFormat("MMM-yyyy"));
        
return jfreechart;
}
   
       一些重要的方法:
     A、增加标记线: 
        xyplot.addRangeMarker(new ValueMarker(550D)); //数值轴
        Quarter quarter = new Quarter(2, 2002);
        xyplot.addDomainMarker(new ValueMarker(quarter.getMiddleMillisecond()));  //时间轴
     B、数据点的调整
        XYLineAndShapeRenderer xylineandshaperenderer = (XYLineAndShapeRenderer)xyplot.getRenderer();
        xylineandshaperenderer.setDefaultShapesVisible(true);  //数据点可见
        xylineandshaperenderer.setSeriesFillPaint(0, Color.red);  //数据点填充为红色
        xylineandshaperenderer.setSeriesFillPaint(1, Color.white);  //数据点填充为白色
        xylineandshaperenderer.setUseFillPaint(true);    //应用
     C、平均值曲线 
       这个曲线有什么用呢?很简单的例子,这里有一个以半年每天为单位的数据绘制的曲线,我们想看看以月为单位数据
       的变化,这时就可以用到它了。 
        TimeSeries timeseries = createEURTimeSeries();  //就是以半年每天为单位的数据
        TimeSeries timeseries1 = MovingAverage.createMovingAverage(timeseries, 
                                                                   "30 day moving average", 
                                                                   30, //30天为一个周期
                                                                   30); //最开始的30天跳过
        TimeSeriesCollection timeseriescollection = new TimeSeriesCollection();
        timeseriescollection.addSeries(timeseries);
        timeseriescollection.addSeries(timeseries1);
        return timeseriescollection; 
     
六、总结一下
                           dataset                          plot                    renderer                       
  饼图           PieDataset(DefaultPieDataset)           PiePlot                    ------
  柱状图    CatagoryDataset(DefaultCategoryDataset)    CategoryPlot                BarRenderer
  折线图    CatagoryDataset(DefaultCategoryDataset)    CategoryPlot              LineAndShapeRenderer
                  XYDataset(XYSeriesCollection)           XYPlot                XYLineAndShapeRenderer
  时间序列图     XYDataset (TimeSeriesCollection)         XYPlot                XYLineAndShapeRenderer



七、Item Lable 
   这里以柱状图为例说明,具体来说就是在每个柱状上显示它的数据,具体有下面内容:
   A、使 Item Lable 可见
   B、调整 Item Lable 的颜色、字体等
   C、调整 Item Lable 的位置
   D、定制 Item Lable 的内容
   1、分配一个 Lable Generator 给 renderer
      BarRenderer barrenderer = (BarRenderer)categoryplot.getRenderer();
      GategoryLableGenerator generator =new StandardGategoryLableGenerator(
           "{2}", new DecimalFormat("0.00")    //调整显示的数字和字符格式
      );
      barrenderer.setLableGenerator(generator);
   2、使 Item Lable 可见
      barrenderer.setItemLableVisible(true);
   3、调整 Item Lable 的颜色、字体等
      barrenderer.setItemLablePaint(Color.red);
      barrenderer.setItemLableFont(new Font("SansSerif",Font.PLAIN,10));
   4、调整 Item Lable 的位置
      这里涉及到一个新的对象 ItemLablePosition , ItemLablePosition的构造函数有两个或四个参数
      public ItemLabelPosition(ItemLabelAnchor itemLabelAnchor,
                         org.jfree.ui.TextAnchor textAnchor,
                         org.jfree.ui.TextAnchor rotationAnchor,
                         double angle)
      itemLabelAnchor - Item Lable 的位置 (最重要的!!)
      textAnchor - Item Lable里包含的正文相对于Item Lable 的位置
      rotationAnchor - Item Lable里包含的正文旋转的位置
      angle - 旋转的角度
      ItemLabelPosition itemlabelposition = new ItemLabelPosition(ItemLabelAnchor.INSIDE12, 
                                                      TextAnchor.CENTER_RIGHT, 
                                                      TextAnchor.CENTER_RIGHT, 
                                                      -1.57D);
      barrenderer.setPositiveItemLabelPosition(itemlabelposition); 
   这样就可以每个柱状上显示它的数据了,当然可以定制 Item Lable 的内容,比如 Item Lable text 超过100的才
   显示,这样就需要定制自己的类,它要实现GategoryLableGenerator 接口,实现generateItemLable()方法。
   
了解了jFreeChart ,现在要使用cewolf 。具体在web 中如何配置,就不说了。首先也是了解cewolf 工作的流程,然后对
它的标签进行说明.

一、cewolf 产生图形的流程
   创建一个数据源(dataset)来包含将要在图形中显示的数据?????>><cewolf:chart/>标签对图形进行调整
   ??????>><cewolf:img/>标签把图形输出
 1、创建一个数据源(dataset)
   创建数据源基本上和上面一样,所不同的是 cewolf 对其重新进行了包装,它提供了一个DatasetProducer 接口,你需要
   实现这一接口,下面是一个例子
  DatasetProducer timeData = new DatasetProducer() {
    public Object produceDataset(Map params) {  //cewolf 对其重新进行了包装
      TimeSeries ts = new TimeSeries("Cewolf Release Schedule", Month.class);//怎么样?和上面一样吧
      ts.add(new Month(7, 2002), 0.1);
      ts.add(new Month(8, 2002), 0.4);
      ts.add(new Month(9, 2002), 0.9);
      ts.add(new Month(10, 2002), 1.0);
      return new TimeSeriesCollection(ts);
    }
    public String getProducerId() {  //返回唯一的ID
      return "TimeDataProducer";
    }
    public boolean hasExpired(Map params, Date since) { //默认就好
      return false;
    }
  };
  pageContext.setAttribute("timeData", timeData); //产生完以后要把它放到页面中保存以给 cewolf标签调用
 2、<cewolf:chart/>标签
  <cewolf:chart id="timeChart"     //这个id要唯一,给下边<cewolf:img/>标签引用
                title="TimeSeries"  //图形的标题
                type="timeseries"   //图形的类型 
                xaxislabel="x-values"    //横轴 Lable
                yaxislabel="y-values">   //纵轴Lable
    <cewolf:colorpaint color="#EEEEFF"/>  //图形的背景色
    <cewolf:data>
        <cewolf:producer id="timeData"/>  //引用上面产生的数据
    </cewolf:data>
  </cewolf:chart> 
  一些说明:
  关于图形的背景色,还有两个选择,分别是
    <cewolf:gradientpaint>   //产生色彩倾斜的背景
        <cewolf:point x="0" y="0" color="#AAAAFFEE" />
        <cewolf:point x="300" y="0" color="#DDDDFF" />
    </cewolf:gradientpaint>
  和
    <cewolf:texturepaint image="/img/bg.jpg" width="60" height="60" /> //加入背景图案
 3、<cewolf:img/>标签
   <cewolf:img chartid="timeChart"   //就是上面那个 id
               renderer="/cewolf"    //这个是必需的!web.xml 中有配置
               width="300"         //宽
               height="300" />      //高
   还有一种图形输出方式:
  <img src='<cewolf:imgurl chartid="foobar" renderer="/cewolf" width="100" height="100"/>'>
  很明显,这种方式把图形包含到 Html 的<img/>中
 4、进一步调整
   看到上面的步骤,你可能会认为用 cewolf 输出图形是如此的简单,是这样的,但看了最开始的 jFreeChart 对图形
   的一些调整,你会想我如何调整呢?我不想用默认值,我想输出更复杂的图形。很好,我是这样做的:
   这里要介绍一个新的接口ChartPostProcessor  和一个标签<cewolf:chartpostprocessor/>
   我们要写自己的类实现这个ChartPostProcessor 接口,然后再用标签<cewolf:chartpostprocessor/>调用我们所写
   的类
  ChartPostProcessor dataColor = new ChartPostProcessor() {
    public void processChart(Object chart, Map params) {  //这个接口就这一个方法
      CategoryPlot plot = (CategoryPlot) ((JFreeChart) chart).getPlot(); //看到了什么??!!对,获得了plot!
                                                                 下面就可以通过plot 对图形进行调整!!          
      plot.setAxisOffset(new RectangleInsets(5D, 5D, 5D, 5D));  //一个实验,坐标轴与图分离
      for (int i = 0; i < params.size(); i++) {   //这里的params 是通过标签<cewolf:chartpostprocessor/>输入的!
        String colorStr = (String) params.get(String.valueOf(i));
        plot.getRenderer().setSeriesPaint(i, java.awt.Color.decode(colorStr));//看到 renderer了吧,又可以大
                                                                                干一场了,嘿嘿!
      }
    }
  };
  pageContext.setAttribute("dataColor", dataColor); //记得要放起来噢
  具体引用:
<cewolf:chart id="stackedHorizontalBar" title="StackedHorizontalBar" 
              type="stackedHorizontalBar" xaxislabel="Fruit" yaxislabel="favorite">
    <cewolf:data>
        <cewolf:producer id="categoryData" />
    </cewolf:data>
    <cewolf:chartpostprocessor id="dataColor">   //在这里!!
        <cewolf:param name="0" value='<%= "#FFFFAA" %>'/>
        <cewolf:param name="1" value='<%= "#AAFFAA" %>'/>
        <cewolf:param name="2" value='<%= "#FFAAFF" %>'/>
        <cewolf:param name="3" value='<%= "#FFAAAA" %>'/>
    </cewolf:chartpostprocessor>
</cewolf:chart>  
 我们当然也可以在实现ChartPostProcessor 接口的类里把一切都做好,然后这么用:
    <cewolf:chartpostprocessor id="dataColor"/>