学习Java中的日期和时间处理及Java日历小程序的编写

Date(long millisec)

import java.util.Date;
public class DateDemo {
  public static void main(String args[]) {
    // Instantiate a Date object
    Date date = new Date();
    // display time and date using toString()
    System.out.println(date.toString());
  }
}

Mon May 04 09:51:52 CDT 2009

import java.util.*;
import java.text.*;
public class DateDemo {
  public static void main(String args[]) {
   Date dNow = new Date( );
   SimpleDateFormat ft = 
   new SimpleDateFormat ("E yyyy.MM.dd 'at' hh:mm:ss a zzz");
   System.out.println("Current Date: " + ft.format(dNow));
  }
}

Current Date: Sun 2004.07.18 at 04:14:09 PM PDT

import java.util.Date;
public class DateDemo {
 public static void main(String args[]) {
   // Instantiate a Date object
   Date date = new Date();
   // display time and date using toString()
   String str = String.format("Current Date/Time : %tc", date );
   System.out.printf(str);
 }
}

Current Date/Time : Sat Dec 15 16:37:57 MST 2012

import java.util.Date;
public class DateDemo {
  public static void main(String args[]) {
    // Instantiate a Date object
    Date date = new Date();
    // display time and date using toString()
    System.out.printf("%1$s %2$tB %2$td, %2$tY", 
             "Due date:", date);
  }
}

Due date: February 09, 2004

import java.util.Date;
public class DateDemo {
  public static void main(String args[]) {
    // Instantiate a Date object
    Date date = new Date();
    // display formatted date
    System.out.printf("%s %tB %<te, %<tY", 
             "Due date:", date);
  }
}

Due date: February 09, 2004

import java.util.*;
import java.text.*;
public class DateDemo {
  public static void main(String args[]) {
   SimpleDateFormat ft = new SimpleDateFormat ("yyyy-MM-dd"); 
   String input = args.length == 0 ? "1818-11-11" : args[0]; 
   System.out.print(input + " Parses as "); 
   Date t; 
   try { 
     t = ft.parse(input); 
     System.out.println(t); 
   } catch (ParseException e) { 
     System.out.println("Unparseable using " + ft); 
   }
  }
}

$ java DateDemo
1818-11-11 Parses as Wed Nov 11 00:00:00 GMT 1818
$ java DateDemo 2007-12-01
2007-12-01 Parses as Sat Dec 01 00:00:00 GMT 2007

import java.util.*;
public class SleepDemo {
  public static void main(String args[]) {
   try { 
     System.out.println(new Date( ) + "\n"); 
     Thread.sleep(5*60*10); 
     System.out.println(new Date( ) + "\n"); 
   } catch (Exception e) { 
     System.out.println("Got an exception!"); 
   }
  }
}

Sun May 03 18:04:41 GMT 2009
Sun May 03 18:04:51 GMT 2009

import java.util.*;
public class DiffDemo {
  public static void main(String args[]) {
   try {
     long start = System.currentTimeMillis( );
     System.out.println(new Date( ) + "\n");
     Thread.sleep(5*60*10);
     System.out.println(new Date( ) + "\n");
     long end = System.currentTimeMillis( );
     long diff = end - start;
     System.out.println("Difference is : " + diff);
   } catch (Exception e) {
     System.out.println("Got an exception!");
   }
  }
}

Sun May 03 18:16:51 GMT 2009
Sun May 03 18:16:57 GMT 2009
Difference is : 5993

import java.util.*;
public class GregorianCalendarDemo {
  public static void main(String args[]) {
   String months[] = {
   "Jan", "Feb", "Mar", "Apr",
   "May", "Jun", "Jul", "Aug",
   "Sep", "Oct", "Nov", "Dec"};
   int year;
   // Create a Gregorian calendar initialized
   // with the current date and time in the
   // default locale and timezone.
   GregorianCalendar gcalendar = new GregorianCalendar();
   // Display current time and date information.
   System.out.print("Date: ");
   System.out.print(months[gcalendar.get(Calendar.MONTH)]);
   System.out.print(" " + gcalendar.get(Calendar.DATE) + " ");
   System.out.println(year = gcalendar.get(Calendar.YEAR));
   System.out.print("Time: ");
   System.out.print(gcalendar.get(Calendar.HOUR) + ":");
   System.out.print(gcalendar.get(Calendar.MINUTE) + ":");
   System.out.println(gcalendar.get(Calendar.SECOND));
   // Test if the current year is a leap year
   if(gcalendar.isLeapYear(year)) {
     System.out.println("The current year is a leap year");
   }
   else {
     System.out.println("The current year is not a leap year");
   }
  }
}

Date: Apr 22 2009
Time: 11:25:27
The current year is not a leap year

public class CalendarViewer extends JWindow implements ActionListener {
  JPanel calendarYmPanel = null;
  JButton leftButton = new JButton("<<");
  JButton rightButton = new JButton(">>");
  Label yearLabel = new Label();
  Label monthLabel = new Label();
  Label passedDaysLabel = new Label();
  JPanel calendarWdPanel = null;// 是caledar_week和calendar_days的总包容体
  JPanel calendarWeekPanel = null;// 针对周列的布局
  JPanel calendarDaysPanel = null;// 针对日期列的布局
  JPanel calendarExitPanel = null;
  JButton quitButton = new JButton("关闭");
  Border emptyBorder = BorderFactory.createEmptyBorder();
  CalendarController cController = new CalendarController();
  public CalendarViewer() {
    super();
    buildUI();
  }
  public void buildUI() {
    buildTopPanel();
    buildCenterPanel();
    buildBottomPanel();
    setLayout(new BorderLayout());
    。。。。。。
  }
  private void buildTopPanel() {。。。。。。}
  private void buildCenterPanel() {。。。。。。}
  private void buildBottomPanel() {。。。。。。}
  public JPanel updateDaysPanel() {。。。。。。}
  public void updatePassedDaysLabel() {。。。。。。}
  public void actionPerformed(ActionEvent e) {。。。。。。}
  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
       new CalendarViewer();
      }
    });
  }
}

updateDaysPanel();
updatePassedDaysLabel();
CalendarController.java主要处理具体的业务逻辑，而所使用的一些与具体应用无关的日历算法逻辑则交给CalendarModel.java。
CalendarModel.java
public class CalendarModel {
  private int daytab[][] = {
      { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
      { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } };
  public boolean isLeapYear(int year) {
    return ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
  }
  public int dayOfYear(int day, int month, int year) {
    int leap = isLeapYear(year) ? 1 : 0;
    for (int i = 1; i < month; i++)
      day += daytab[leap][i];
    return day;
  }
  public int daysOfMonth(int month, int year) {
    int leap = isLeapYear(year) ? 1 : 0;
    return daytab[leap][month];
  }
  public int dayOfWeek(int day, int month, int year) {
    if (month == 1) {
      month = 13;
      year--;
    }
    if (month == 2) {
      month = 14;
      year--;
    }
    return (day + 2 * month + 3 * (month + 1) / 5 + year + year / 4 - year
       / 100 + year / 400) % 7 + 1;
  }
}