Question

我开发了一个小应用程序，必须使用3D条形图显示公司的前十大销售项目。这些项目将从mysql数据库中检索。

我知道如何从mysql数据库中检索数据，但是如何让它与Neteans上的条形图一起使用？

我如何才能实现这一目标或哪里是帮助我实现这一目标的最佳资源？

Answer 1

实现此目的的方法首先是使用以下编码建立数据库连接，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();

那么你需要使用以下编码来创建和显示netbeans中的图表

//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);

你需要把它放在try catch块中。

请记住，您需要一个Jar文件，允许您从图表的JAR文件中导入必要的数据。

以下是完整的编码集：

//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);
    }
}

在NetBeans中创建3D条形图以显示数据库中的前10个项目

1 个答案: