[英]JFree Chart with data from MySQL Database into a JPanel
我正在嘗試在我的程序中實現一個 JFree Chart,我目前正在開發一個 Java Swing 應用程序。 我想將圖表顯示到應用程序內的面板中。 因此,我要為圖表提取數據的表格如下:
----------------------- | daily_total_statements| ----------------------- | Reference ID (PK) | | Value | | Date | -----------------------
我用來實現圖表的代碼是:
public void buidGraph(JPanel jp) {
DefaultCategoryDataset dataset = createDataset();
JFreeChart chart = ChartFactory.createLineChart(
"Daily Progress",
"Date", // X-Axis Label
"Number of Members", // Y-Axis Label
dataset
);
ChartPanel panel = new ChartPanel(chart);
jp.add(panel);
}
我認為可以工作的數據集代碼,我對此有點困惑:
private DefaultCategoryDataset createDataset() {
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
try {
String query = "SELECT `Value`, `Date` FROM `daily_total_statements`
ORDER BY `Date` ASC";
Connection c = MySQL_Database.getInstance().getConnection();
PreparedStatement ps = c.prepareStatement(query);
ResultSet rs = ps.executeQuery();
String series2 = "Daily progress";
while (rs.next()) {
dataset.addValue(rs.getInt(1), series2, rs.getString(2));
}
} catch (SQLException e) {
JOptionPane.showMessageDialog(null, "Problem creating chart! " + e.getMessage());
}
return dataset;
}
如您所見,我正在為數據庫使用 singleton class。 問題是圖表根本沒有顯示,它只是一個空面板。 請如果你能幫忙! 很抱歉格式和語言不好!
因為ChartPanel
是JPanel
,所以您可以簡單地將其添加到您的框架中,如下所示。 框架的默認布局是BorderLayout
並且默認約束是CENTER
。 而且,
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;
public class GraphTest extends JFrame {
public GraphTest() {
initComponents();
}
private void initComponents() {
add(buildLineGraph());
pack();
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String args[]) {
EventQueue.invokeLater(GraphTest::new);
}
public ChartPanel buildLineGraph() {
DefaultCategoryDataset dataset = createLineGraphDataset();
JFreeChart chart = ChartFactory.createLineChart("Daily Progress",
"Day", "Value", dataset, PlotOrientation.VERTICAL, true, true, false);
return new ChartPanel(chart) {
@Override
public Dimension getPreferredSize() {
return new Dimension(640, 480);
}
};
}
private DefaultCategoryDataset createLineGraphDataset() {
// TODO: use JDBCXYDataset
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.addValue(1, "Result", "Mon");
dataset.addValue(5, "Result", "Tue");
dataset.addValue(7, "Result", "Wed");
return dataset;
}
}
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