Question

你想用mysql数据库创建一个图表，所以我使用了jfreechart，我尝试了这个，

void getData() {

        try {
          String query="SELECT month,profit FROM profit";
         JDBCCategoryDataset dataset=new JDBCCategoryDataset(Database.getConnection(), query);
        JFreeChart chart =ChartFactory.createLineChart("Test", "Month", "Profit", dataset,PlotOrientation.VERTICAL,false,true,true);
        BarRenderer renderer=new BarRenderer();
        CategoryPlot plot=null;
        ChartPanel panel=new ChartPanel(chart);
        p_line.removeAll();
        p_line.add(panel,BorderLayout.CENTER);


    } catch (Exception e) {
        e.printStackTrace();
    }
}

但有例外，

 Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: org/jfree/util/PublicCloneable
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)

Answer 1

您必须下载jcommon-<version>.jar并将其添加到您的类路径中。因为这个jar包含类org/jfree/util/PublicCloneable

如何从java中的mysql数据库获取图表数据？

1 个答案: