请问，我用jfreechart做了一个3d的柱状图，怎么让柱子上显示柱子的值啊？

Question

我已经设置了custombarrenderer3d.setItemLabelsVisible(true);还应该怎么设置？

Answer 1

这是源代码：
package demo;import java.awt.*;
import java.text.NumberFormat;
import javax.swing.JPanel;
import org.jfree.chart.*;
import org.jfree.chart.annotations.CategoryTextAnnotation;
import org.jfree.chart.axis.CategoryAnchor;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.labels.StandardCategoryItemLabelGenerator;
import org.jfree.chart.plot.*;
import org.jfree.chart.renderer.category.BarRenderer3D;
import org.jfree.chart.renderer.category.CategoryItemRenderer;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.*;public class BarChart3DDemo4 extends ApplicationFrame
{
    static class CustomBarRenderer3D extends BarRenderer3D
    {        public Paint getItemPaint(int i, int j)
        {
            CategoryDataset categorydataset = getPlot().getDataset();
            double d = categorydataset.getValue(i, j).doubleValue();
            if(d >= 0.69999999999999996D)
            {
                return Color.green;
            } else
            {
                return Color.red;
            }
        }        public CustomBarRenderer3D()
        {
        }
    }
    public BarChart3DDemo4(String s)
    {
        super(s);
        CategoryDataset categorydataset = createDataset();
        JFreeChart jfreechart = createChart(categorydataset);
        ChartPanel chartpanel = new ChartPanel(jfreechart);
        chartpanel.setPreferredSize(new Dimension(500, 270));
        setContentPane(chartpanel);
    }    private static CategoryDataset createDataset()
    {
        DefaultCategoryDataset defaultcategorydataset = new DefaultCategoryDataset();
        defaultcategorydataset.addValue(77D, "Series 1", "四月");
        defaultcategorydataset.addValue(93D, "Series 1", "五月");
        defaultcategorydataset.addValue(58D, "Series 1", "六月");
//       defaultcategorydataset.addValue(0.75D, "Series 1", "Ellen");
//      defaultcategorydataset.addValue(0.63D, "Series 1", "Jack");
        defaultcategorydataset.addValue(94D, "Series 1", "七月");
        defaultcategorydataset.addValue(70D, "Series 1", "八月");
        defaultcategorydataset.addValue(65D, "Series 1", "九月");
        return defaultcategorydataset;
    }    private static JFreeChart createChart(CategoryDataset categorydataset)
    {
        JFreeChart jfreechart = ChartFactory.createBarChart3D("四月至九月", "月份", "人数", categorydataset, PlotOrientation.VERTICAL, false, true, false);
        CategoryPlot categoryplot = (CategoryPlot)jfreechart.getPlot();
        categoryplot.setBackgroundPaint(Color.white);
        
        CustomBarRenderer3D custombarrenderer3d = new CustomBarRenderer3D();
        
        
        
//        CategoryItemRenderer categoryitemrenderer = categoryplot.getRenderer();
//        categoryitemrenderer.setItemLabelsVisible(true);
        ValueMarker valueer = new ValueMarker(0.69999999999999996D, new Color(100, 200, 255), new BasicStroke(1.0F), new Color(200, 200, 255), new BasicStroke(1.0F), 1.0F);
        categoryplot.addRangeMarker(valueer, Layer.BACKGROUND);
        custombarrenderer3d.setItemLabelPaint(Color.GREEN);
        custombarrenderer3d.setItemLabelGenerator(new StandardCategoryItemLabelGenerator());
        custombarrenderer3d.setItemLabelFont(new Font("黑体",Font.PLAIN,12));
        custombarrenderer3d.setItemLabelsVisible(true);
        
        custombarrenderer3d.setMaximumBarWidth(0.050000000000000003D);
        categoryplot.setRenderer(custombarrenderer3d);
        CategoryTextAnnotation categorytextannotation = new CategoryTextAnnotation("", "Robert", 0.70999999999999996D);
//        CategoryTextAnnotation categorytextannotation = new CategoryTextAnnotation();
        categorytextannotation.setCategoryAnchor(CategoryAnchor.START);
        categorytextannotation.setFont(new Font("SansSerif", 0, 12));
        categorytextannotation.setTextAnchor(TextAnchor.BOTTOM_LEFT);
        categoryplot.addAnnotation(categorytextannotation);
        NumberAxis numberaxis = (NumberAxis)categoryplot.getRangeAxis();
  //      numberaxis.setNumberFormatOverride(NumberFormat.getPercentInstance());
        numberaxis.setNumberFormatOverride(NumberFormat.getNumberInstance());
        
        
        
        
        return jfreechart;
    }    public static JPanel createDemoPanel()
    {
        JFreeChart jfreechart = createChart(createDataset());
        return new ChartPanel(jfreechart);
    }    public static void main(String args[])
    {
        BarChart3DDemo4 barchart3ddemo4 = new BarChart3DDemo4("3D Bar Chart Demo 4");
        barchart3ddemo4.pack();
        RefineryUtilities.centerFrameOnScreen(barchart3ddemo4);
        barchart3ddemo4.setVisible(true);
    }
}

Answer 2

还应该设计柱子的最小宽度，否则有可能宽度太小而显示不出数据
eg:  
....     
BarRenderer3D renderer1=new BarRenderer3D();
       renderer1.setItemLabelGenerator(new StandardCategoryItemLabelGenerator());
renderer1.setItemLabelFont(new Font("黑体",Font.PLAIN,12));
         renderer1.setItemLabelsVisible(true);//显示每个柱子上的数据
renderer1.setMinimumBarLength(1.0);
...

Answer 3

DefaultCategoryDataset dataset = new DefaultCategoryDataset();
String sql  = "SELECT...";
.
.
.ResultSet rs= ...;
try 
{
while(rs.next())
{
float f = rs.getFloat("...");
String str= rs_.getString("date");
dataset.addValue(f, "1", str);
}
}
catch (Exception ex)
{
ex.printStackTrace();
}
JFreeChart chart = ChartFactory.createBarChart3D("营业收入统计图", 
                  "日    期",
                  "营业金额",
                  dataset,
                  PlotOrientation.VERTICAL,
                  false,
                  false,
                  false);

JDBCCategoryDataset data = new JDBCCategoryDataset();
ChartPanel chartPanel =new ChartPanel(chart);
chartPanel.setChart(chart);