mysql - 在 NetBeans 中创建 3D 条形图以显示数据库中的前 10 个项目

Question

我开发了一个小型应用程序，它必须使用 3D 条形图显示公司的十大畅销商品。这些项目将从 mysql 数据库中检索。

我确实了解如何从 mysql 数据库检索数据，但我如何才能让它与 Neteans 上的条形图一起使用？

我怎样才能实现这一目标，或者哪里有帮助我实现这一目标的最佳资源？

Answer 1

解决此问题的方法是首先使用以下代码建立数据库连接，如下所示:

  //connects to the database
    Class.forName("com.mysql.jdbc.Driver");
        Connection con = (Connection)
        DriverManager.getConnection("jdbc:mysql://localhost:3306/DBName","root","password");
        //select statement calling data from the sales database
        PreparedStatement stmt = con.prepareStatement("SELECT * FROM dbsales ORDER BY usold DESC LIMIT 10");
        ResultSet rs = stmt.executeQuery();

然后您将需要使用以下代码在 netbeans 中创建和显示图表

//creates the graph object
        DefaultCategoryDataset ddataset = new DefaultCategoryDataset();
        while (rs.next()) 
        {
            //retrieves data from the database for the graph
            ddataset.setValue(new Double(rs.getDouble("usold")), rs.getString("pbrand")  + " " + rs.getString("pname"),  rs.getString("pid"));
        }
         //generates the graph
         JFreeChart chart = ChartFactory.createBarChart3D("Top 10 Selling Products", "Products", "Number of Units Sold", ddataset);
         //creates the graph title
        chart.getTitle().setPaint(Color.RED);
        //plots the graph
        CategoryPlot p = chart.getCategoryPlot();
        p.setRangeGridlinePaint(Color.BLUE);
        //creates the frame 
        ChartFrame frame2 = new ChartFrame("Top 10 Selling Products", chart);
        //sets the frame visible
        frame2.setVisible(true);
        //sets the frame size
        frame2.setSize(900,700);

您需要将其放入 try catch block 中。

请记住，您将需要一个 Jar 文件，它允许您从这些 JAR 文件中为图表导入必要的数据。

下面是完整的编码集:

//method for top ten graph
private void topten()
{
    try
    {
        //connects to the database
    Class.forName("com.mysql.jdbc.Driver");
        Connection con = (Connection)
        DriverManager.getConnection("jdbc:mysql://localhost:3306/DBName","root","password");
        //select statement calling data from the sales database
        PreparedStatement stmt = con.prepareStatement("SELECT * FROM dbsales ORDER BY usold DESC LIMIT 10");
        ResultSet rs = stmt.executeQuery();
        //creates the graph object
        DefaultCategoryDataset ddataset = new DefaultCategoryDataset();
        while (rs.next()) 
        {
            //retrieves data from the database for the graph
            ddataset.setValue(new Double(rs.getDouble("usold")), rs.getString("pbrand")  + " " + rs.getString("pname"),  rs.getString("pid"));
        }
         //generates the graph
         JFreeChart chart = ChartFactory.createBarChart3D("Top 10 Selling Products", "Products", "Number of Units Sold", ddataset);
         //creates the graph title
        chart.getTitle().setPaint(Color.RED);
        //plots the graph
        CategoryPlot p = chart.getCategoryPlot();
        p.setRangeGridlinePaint(Color.BLUE);
        //creates the frame 
        ChartFrame frame2 = new ChartFrame("Top 10 Selling Products", chart);
        //sets the frame visible
        frame2.setVisible(true);
        //sets the frame size
        frame2.setSize(900,700);
        }
     catch(Exception e)
    {
        //error message for when the graph cannot be generated
        JOptionPane.showMessageDialog(null, "Error 111: Unable to identify and load best ten sellers for graph", "Database Error", JOptionPane.ERROR_MESSAGE);
    }
}