Java的统计图表（JFreeChart的应用）

第一步、导入库文件（jar包）：

      jcommon-1.0.23.jar

      jfreechart-1.0.19.jar

第二步：配置web.xml文件（将JFreeChart组件中已有的DisplayChart在web.xml文件进行声明）

   

      <servlet-name>DisplayChart</servlet-name>

      <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class>

 

      <servlet-name>DisplayChart</servlet-name>

      <url-pattern>/DisplayChart</url-pattern>

 

第三步：创建数据集：

     1、设计数据库（明确需要提取的数据）

    2、Dao层设计：实体类、查询方法

     public int chart(String sql) {

       int count = 0;

       try {

           ps = DBUtils.getConn().prepareStatement(sql);

           ResultSet rs = ps.executeQuery();      

          while(rs.next())

           {

               count = rs.getInt(1);

           }

       } catch (SQLException e) {        

          e.printStackTrace();

       }

       return count;

    }   

  3、 创建一个类：用于生成不同类型的图表

      public class ChartUtil {

 

            private static PieDataset getPieDataset() throws Exception{

        

        DefaultPieDataset dataset=new DefaultPieDataset();

        String s1="SELECT COUNT(*) FROM student WHERE Education='高中'";

        String s2="SELECT COUNT(*) FROM student WHERE Education='大专'";

        String s3="SELECT COUNT(*) FROM student WHERE Education='本科'";

        String s4="SELECT COUNT(*) FROM student WHERE Education='硕士'";

        IStuDAO dao=DaoFactory.getStudentDao();

        

        dataset.setValue("硕士",dao.select(s4));

        dataset.setValue("专科",dao.select(s2));

        dataset.setValue("本科",dao.select(s3));

        dataset.setValue("高中",dao.select(s1));

        

        return dataset;

    }

 

    public static JFreeChart getPieJFreeChart() throws Exception{

        

        // 以下是饼图

        PieDataset dataset=getPieDataset();//获得饼图

        JFreeChart chart=ChartFactory.createPieChart("学历分布情况",dataset,true,true,false);//调用工厂类创建饼图

        

        PiePlot piePlot=(PiePlot)chart.getPlot();

        piePlot.setLabelFont(new Font("宋体",Font.PLAIN,14));//设置图表字体

        

        TextTitle textTitle=chart.getTitle();

        textTitle.setFont(new Font("宋体",Font.BOLD,20));//设置标题

        

        LegendTitle legendTitle=chart.getLegend();

        legendTitle.setItemFont(new Font("宋体",Font.PLAIN,12));//设置图例

        

        piePlot.setLabelGenerator(new StandardPieSectionLabelGenerator("{0}({1}人):{2}"));//当前类别的百分比

        

        //分离饼图

        piePlot.setExplodePercent("本科",0.1);

        piePlot.setExplodePercent("专科",0.1);

        piePlot.setExplodePercent("高中",0.1);

        piePlot.setExplodePercent("硕士",0.1);

        

        //piePlot.setSimpleLabels(true);

        

        //piePlot.setForegroundAlpha(0.7f);//设置3D饼图的透明度

        //piePlot.setDepthFactor(0.1f);//设置Z轴的高度，取值范围在0~1之间,值越小，Z轴越低

        

        piePlot.setBackgroundPaint(Color.white);

        piePlot.setOutlineVisible(false);

        chart.setAntiAlias(false);

        

        return chart;

    }

        //以下是柱形图

    public static JFreeChart getCatJFreeChart() throws Exception{

        

        CategoryDataset dataset=getCategoryDataset();

        JFreeChart chart=ChartFactory.createBarChart("年龄分布情况","年龄段","人数",dataset,PlotOrientation.VERTICAL,false,false,false);

        

        //图表标题

        TextTitle textTitle=chart.getTitle();

        textTitle.setFont(new Font("宋体",Font.PLAIN,20));

        

        //图表(柱形图)

        CategoryPlot categoryPlot=chart.getCategoryPlot();

        CategoryAxis categoryAxis=categoryPlot.getDomainAxis();

        

        //设置柱形的颜色

        BarRenderer renderer=(BarRenderer)categoryPlot.getRenderer();

        renderer.setSeriesPaint(0,Color.RED);

        //X轴字体

        categoryAxis.setTickLabelFont(new Font("宋体",Font.PLAIN,14));

        

        //X轴标签字体

        categoryAxis.setLabelFont(new Font("宋体",Font.PLAIN,14));

        //categoryAxis.setAxisLinePaint(Color.BLUE);//

        

        //Y轴字体

        ValueAxis valueAxis=categoryPlot.getRangeAxis();

        valueAxis.setLabelFont(new Font("宋体",Font.PLAIN,14));

        //valueAxis.setAxisLinePaint(Color.BLUE);*/

        return chart;

    }

    

    public static CategoryDataset getCategoryDataset() throws Exception{

        

        DefaultKeyedValues keyedValues=new DefaultKeyedValues();

        

        String s1="SELECT COUNT(*) FROM student WHERE Age<20";

        String s2="SELECT COUNT(*) FROM student WHERE Age between 20 and 25";

        String s3="SELECT COUNT(*) FROM student WHERE Age between 25 and 30";

        String s4="SELECT COUNT(*) FROM student WHERE Age between 30 and 35";

        String s5="SELECT COUNT(*) FROM student WHERE Age>35";

        IStuDAO dao=DaoFactory.getStudentDao();

        

        keyedValues.addValue("20岁以下",dao.select(s1));

        keyedValues.addValue("20~25岁",dao.select(s2));

        keyedValues.addValue("25~30岁",dao.select(s3));

        keyedValues.addValue("30~35岁",dao.select(s4));

        keyedValues.addValue("35岁以上",dao.select(s5));

        

        CategoryDataset dataset=DatasetUtilities.createCategoryDataset("年龄分布情况",keyedValues);

        

        return dataset;

    }

}

 

第四步、创建图表对象

   

         String filename=null;

    

       //饼图对象

      filename=ServletUtilities.saveChartAsJPEG(ChartUtil.getPieJFreeChart(),500, 350, session);

   

        //柱状图对象

      filename=ServletUtilities.saveChartAsJPEG(ChartUtil.getCatJFreeChart(),500, 350, session)；

 

第五步、获取图片：

 

          String charUrl="DisplayChart?filename="+filename;

 

 

第六步、在web中显示图片：