从Mysql DB填充JFreechart TimeSeriesCollection？

我正在尝试在我的应用程序中创建一个图表，它可以返回几个月内的温度。

此图表是JFreechart TimeSeriesCollection，我无法让图表从数据库中读取正确的数据。

它显示了一些值，但不是全部，并且没有显示正确的时间。

为了解决这个问题，我试图实现这里发布的图表，但仍然无法解决我的问题，即使已经去看了这个问题 ，正如人们建议的那样

public class NewClass extends ApplicationFrame { Connection conexao = null; PreparedStatement pst= null; ResultSet rs = null; public NewClass(String title) throws SQLException, ParseException { super(title); ChartPanel chartPanel = (ChartPanel) createDemoPanel(); chartPanel.setPreferredSize(new java.awt.Dimension(500, 270)); setContentPane(chartPanel); } private static JFreeChart createChart(XYDataset dataset) { JFreeChart chart = ChartFactory.createTimeSeriesChart( "Temperatura/Date", // title "Date", // x-axis label "Temperatura", // y-axis label dataset, // data true, // create legend? true, // generate tooltips? false // generate URLs? ); XYPlot plot = (XYPlot) chart.getPlot(); DateAxis axis = (DateAxis) plot.getDomainAxis(); axis.setDateFormatOverride(new SimpleDateFormat("yyyy-MM-dd")); return chart; } private static XYDataset createDataset() throws SQLException, ParseException { Connection con = null; String databaseURL = "jdbc:mysql://localhost:3306/world"; String driverName = "com.mysql.jdbc.Driver"; String user = "root"; String password = "rootadmin"; try { Class.forName(driverName).newInstance(); } catch (Exception ex) { System.out.println(""); } con = (Connection) DriverManager.getConnection(databaseURL, user, password); if (!con.isClosed()) { System.out.println("Successfully connected to the DataBase Server..."); } Statement statement; statement = (Statement) con.createStatement(); String selectQuery = "select (CONCAT(`data_registo`, ' ', hora_registo)) as data, temperatura, idSensor from registos where idSensor like 'BrgTH001' "; ResultSet resultSet = null; resultSet = statement.executeQuery(selectQuery); TimeSeries s1 = new TimeSeries("Thermomether01"); while (resultSet.next()) { String idSensor = (String) resultSet.getObject("idSensor"); String data = (String) resultSet.getObject("data"); String temperatura = (String) resultSet.getObject("temperatura"); SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm"); Date dateI = sdf2.parse(data); System.out.println("" + idSensor + " " + data + " " + temperatura+ " | " ); s1.addOrUpdate(new Hour(dateI), value); } resultSet.close(); TimeSeriesCollection dataset = new TimeSeriesCollection(); dataset.addSeries(s1); return dataset; } public static JPanel createDemoPanel() throws SQLException, ParseException { JFreeChart chart = createChart(createDataset()); ChartPanel panel = new ChartPanel(chart); panel.setFillZoomRectangle(true); panel.setMouseWheelEnabled(true); return panel; } public static void main(String[] args) throws SQLException, ParseException { NewClass demo = new NewClass("Chart"); demo.pack(); demo.setVisible(true); } } 

这是我的代码结果的图表。 但查询的结果是：

 Thermomether01 2014-04-01 08:47:11 23.8 | Thermomether01 2014-04-01 08:47:11 23.8 | Thermomether01 2014-04-01 08:51:20 23.9 | Thermomether01 2014-04-01 08:53:24 23.9 | Thermomether01 2014-04-01 08:55:28 23.9 | Thermomether01 2014-04-01 09:43:26 24.1 | Thermomether01 2014-04-01 09:48:39 24.0 | Thermomether01 2014-04-01 09:50:44 24.1 | Thermomether01 2014-04-01 09:52:48 24.0 | Thermomether01 2014-04-01 09:54:52 24.1 | Thermomether01 2014-04-01 09:56:56 24.1 | Thermomether01 2014-04-01 09:59:01 24.1 | . . . Thermomether01 2014-06-13 09:35:36 19.2 | Thermomether01 2014-06-13 10:03:00 18.7 | Thermomether01 2014-06-13 10:33:41 19.0 | Thermomether01 2014-06-16 08:57:57 19.1 | Thermomether01 2014-06-16 09:07:54 18.9 | Thermomether01 2014-06-16 09:08:40 19.0 | Thermomether01 2014-06-16 09:36:28 19.1 | Thermomether01 2014-06-16 10:03:51 18.8 | Thermomether01 2014-06-16 10:31:14 19.2 | Thermomether01 2014-06-16 11:00:17 19.1 | Thermomether01 2014-06-16 11:27:38 19.2 | Thermomether01 2014-06-16 11:54:59 19.1 | Thermomether01 2014-06-16 12:51:24 18.5 | 

等等…

如此处所示，它不显示所有值，也不列出小时数。

– – – – – – – – – – – 编辑 – – – – – – – – – – –

 select (CONCAT(`data_registo`, ' ', hora_registo)) as data, temperatura, idSensor from registos where idSensor like 'Thermometer01' and temperatura not in ('---') and data_registo between '2014-06-01' and '2014-06-10' 

实现这一点并没有改变输出。

Answer 1

我怀疑你在将String转换为Date失去了精确度。 此完整示例在内存中创建合适的数据库表，将其查询到JDBCXYDataset并在时间序列图表中显示数据集。 请注意， JDBCXYDataset识别时间序列数据。 作为检查，将查询JDBCXYDataset以获取返回的日期值。

典型的每小时数据：

 ...
 2014年7月15日下午1:10:25
 2014年7月15日下午2:10:25
 2014年7月15日下午3:10:25
 2014年7月15日下午4:10:25
 2014年7月15日下午5:10:25
 2014年7月15日下午6:10:25
 ...

码：

 import java.awt.EventQueue; import java.sql.Connection; import java.sql.Date; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; import java.sql.Statement; import java.sql.Timestamp; import java.text.DateFormat; import java.util.Calendar; import java.util.Random; import javax.swing.JFrame; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartPanel; import org.jfree.chart.JFreeChart; import org.jfree.data.jdbc.JDBCXYDataset; /** * @see http://stackoverflow.com/a/24762078/230513 */ public class JDBCTest { private static final int N = 24; private static final Random r = new Random(); private void display() { JFrame f = new JFrame("JDBCTest"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JDBCXYDataset jds = createDataset(); JFreeChart chart = ChartFactory.createTimeSeriesChart( "Inventory", "Date", "Count", jds, true, true, false); f.add(new ChartPanel(chart)); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); for (int i = 0; i < jds.getItemCount(); i++) { System.out.println(DateFormat.getDateTimeInstance() .format(new Date(jds.getX(0, i).longValue()))); } } private JDBCXYDataset createDataset() { try { Connection conn = DriverManager.getConnection( "jdbc:h2:mem:test", "", ""); Statement st = conn.createStatement(); st.execute("create table inventory(when timestamp, n1 integer, n2 integer)"); PreparedStatement ps = conn.prepareStatement( "insert into inventory values (?, ?, ?)"); Calendar c = Calendar.getInstance(); for (int i = 0; i < N; i++) { ps.setTimestamp(1, new Timestamp(c.getTimeInMillis())); ps.setInt(2, N / 3 + r.nextInt(N / 2)); ps.setInt(3, N / 2 + r.nextInt(N / 2)); ps.execute(); c.add(Calendar.HOUR_OF_DAY, 1); } JDBCXYDataset jds = new JDBCXYDataset(conn); jds.executeQuery("select when, n1, n2 from inventory"); return jds; } catch (SQLException ex) { ex.printStackTrace(System.err); } return null; } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new JDBCTest().display(); } }); } }