我正在尝试在我的应用程序中创建一个图表,它会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,我尝试将图表实现为here发布,但仍然无法解决我的问题,即使已经去看了这个question,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.
解决方法:
我怀疑你在将String转换为Date时失去了精确度.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可识别时间序列数据.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：
… Jul 15, 2014 1:10:25 PM Jul 15, 2014 2:10:25 PM Jul 15, 2014 3:10:25 PM Jul 15, 2014 4:10:25 PM Jul 15, 2014 5:10:25 PM Jul 15, 2014 6:10:25 PM …
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 https://*.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();
}
});
}
}