如何使用互联网而不是设备或系统获取当前日期和时间？

Question

我希望从Google或YouTube或互联网上获取当前的日期和时间。我不想得到设备或系统的时间。

Answer 1

我就这样做了（注意你需要下载并导入apache libraries）：

package timeinternet;
import java.net.InetAddress;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
import org.apache.commons.net.ntp.NTPUDPClient; 
import org.apache.commons.net.ntp.TimeInfo;

/**
 *
 * @author Windows 8 Java
 */
public class NewJFrame extends javax.swing.JFrame {

    /**
     * Creates new form NewJFrame
     */
    public NewJFrame() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("jLabel1");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(206, Short.MAX_VALUE)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 154, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(40, 40, 40))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(141, 141, 141)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(58, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) throws Exception {
        /*
         * Set the Nimbus look and feel
         */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /*
         * If Nimbus (introduced in Java SE 6) is not available, stay with the
         * default look and feel. For details see
         * http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        String str;
        String TIME_SERVER = "time-a.nist.gov";   
NTPUDPClient timeClient = new NTPUDPClient();
InetAddress inetAddress = InetAddress.getByName(TIME_SERVER);
TimeInfo timeInfo = timeClient.getTime(inetAddress);
long returnTime = timeInfo.getMessage().getTransmitTimeStamp().getTime();
//long returnTime = timeInfo.getMessage().getReceiveTimeStamp().getTime();
Date time = new Date(returnTime);
System.out.println("" + time);


 Calendar calendar = Calendar.getInstance();
        TimeZone fromTimeZone = calendar.getTimeZone();
        TimeZone toTimeZone = TimeZone.getTimeZone("CST");

        calendar.setTimeZone(fromTimeZone);
        calendar.add(Calendar.MILLISECOND, fromTimeZone.getRawOffset() * -1);
        if (fromTimeZone.inDaylightTime(calendar.getTime())) {
            calendar.add(Calendar.MILLISECOND, calendar.getTimeZone().getDSTSavings() * -1);
        }

        calendar.add(Calendar.MILLISECOND, toTimeZone.getRawOffset());
        if (toTimeZone.inDaylightTime(calendar.getTime())) {
            calendar.add(Calendar.MILLISECOND, toTimeZone.getDSTSavings());
        }

        System.out.println(calendar.getTime());




str = (time.toString());
//jLabel1.setText("a");
        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    // End of variables declaration                   
}