Java Calendar类

Java Calendar 是时间操作类,Calendar 抽象类定义了足够的方法，在某一特定的瞬间或日历上，提供年、月、日、小时之间的转换提供方法。

格式

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
Y	Week year	Year	2009; 09
M	Month in year (context sensitive)	Month	July; Jul; 07
L	Month in year (standalone form)	Month	July; Jul; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day name in week	Text	Tuesday; Tue
u	Day number of week (1 = Monday, ..., 7 = Sunday)	Number	1
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	RFC 822 time zone	-0800
X	Time zone	ISO 8601 time zone	-08; -0800; -08:00

Calendar类注意事项

Calendar 的 month 从 0 开始，也就是全年 12 个月由 0 ~ 11 进行表示。

而 Calendar.DAY_OF_WEEK 定义和值如下：

Calendar.SUNDAY = 1
Calendar.MONDAY = 2
Calendar.TUESDAY = 3
Calendar.WEDNESDAY = 4
Calendar.THURSDAY = 5
Calendar.FRIDAY = 6
Calendar.SATURDAY = 7

取值

取值当天

public String getThisToday(){
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
cal.set(Calendar.HOUR_OF_DAY,0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND,0);
    String start = sdf.format(cal.getTime());
    cal.set(Calendar.HOUR_OF_DAY,23);
    cal.set(Calendar.MINUTE, 59);
    cal.set(Calendar.SECOND,59);
    String end = sdf.format(cal.getTime());
    return start+"|"+end;
}

取值本周

public String getThisWeekDate(){
	SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	Calendar ca = Calendar.getInstance();
	ca.setFirstDayOfWeek(Calendar.MONDAY);
	ca.set(Calendar.DAY_OF_WEEK,Calendar.SUNDAY);
	ca.set(ca.get(Calendar.YEAR), ca.get(Calendar.MONTH),ca.get(Calendar.DATE),23,59,59);
	String end = sdf.format(ca.getTime());
	ca.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
	ca.set(Calendar.HOUR_OF_DAY,0);
	ca.set(Calendar.MINUTE, 0);
	ca.set(Calendar.SECOND,0);
	String start = sdf.format(ca.getTime());
	return start+"|"+end;
 }

取值本月日期段

public String getThisMonthDate(){
     SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
     Calendar cc2 = Calendar.getInstance();
     int maxMonthDay = cc2.getActualMaximum(Calendar.DAY_OF_MONTH);
     cc2.set(cc2.get(Calendar.YEAR), cc2.get(Calendar.MONTH),maxMonthDay,23,59,59);
     String end = sdf.format(cc2.getTime());
     cc2.set(cc2.get(Calendar.YEAR), cc2.get(Calendar.MONTH),1,0,0,0);
     String start = sdf.format(cc2.getTime());
     return start+"|"+end;
}

实例

public static void main(String[] args)  
{  
  // 字符串转换日期格式  
  DateFormat fmtDateTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
  // 得到日期格式对象  
  Date date = fmtDateTime.parse(strDateMake);  

  // 完整显示日期时间  
  String str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS")).format(new Date());  
  System.out.println(str);  

  // 创建 Calendar 对象  
  Calendar calendar = Calendar.getInstance();  
  // 初始化 Calendar 对象，但并不必要，除非需要重置时间  
  calendar.setTime(new Date());  

  // setTime 类似上面一行  
  // Date date = new Date();  
  // calendar.setTime(date);  

  // 显示年份  
  int year = calendar.get(Calendar.YEAR);  
  System.out.println("YEAR is = " + String.valueOf(year));  

  // 显示月份 (从0开始, 实际显示要加一)  
  int MONTH = calendar.get(Calendar.MONTH);  
  System.out.println("MONTH is = " + (MONTH + 1));  

  // 今年的第 N 天  
  int DAY_OF_YEAR = calendar.get(Calendar.DAY_OF_YEAR);  
  System.out.println("DAY_OF_YEAR is = " + DAY_OF_YEAR);  

  // 本月第 N 天  
  int DAY_OF_MONTH = calendar.get(Calendar.DAY_OF_MONTH);  
  System.out.println("DAY_OF_MONTH = " + String.valueOf(DAY_OF_MONTH));  

  // 3小时以后  
  calendar.add(Calendar.HOUR_OF_DAY, 3);  
  int HOUR_OF_DAY = calendar.get(Calendar.HOUR_OF_DAY);  
  System.out.println("HOUR_OF_DAY + 3 = " + HOUR_OF_DAY);  

  // 当前分钟数  
  int MINUTE = calendar.get(Calendar.MINUTE);  
  System.out.println("MINUTE = " + MINUTE);  

  // 15 分钟以后  
  calendar.add(Calendar.MINUTE, 15);  
  MINUTE = calendar.get(Calendar.MINUTE);  
  System.out.println("MINUTE + 15 = " + MINUTE);  

  // 30分钟前  
  calendar.add(Calendar.MINUTE, -30);  
  MINUTE = calendar.get(Calendar.MINUTE);  
  System.out.println("MINUTE - 30 = " + MINUTE);  

  // 格式化显示  
  str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS")).format(calendar.getTime());  
  System.out.println(str);  

  // 重置 Calendar 显示当前时间  
  calendar.setTime(new Date());  
  str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS")).format(calendar.getTime());  
  System.out.println(str);  

  // 创建一个 Calendar 用于比较时间  
  Calendar calendarNew = Calendar.getInstance();  

  // 设定为 5 小时以前，后者大，显示 -1  
  calendarNew.add(Calendar.HOUR, -5);  
  System.out.println("时间比较：" + calendarNew.compareTo(calendar));  

  // 设定7小时以后，前者大，显示 1  
  calendarNew.add(Calendar.HOUR, +7);  
  System.out.println("时间比较：" + calendarNew.compareTo(calendar));  

  // 退回 2 小时，时间相同，显示 0  
  calendarNew.add(Calendar.HOUR, -2);  
  System.out.println("时间比较：" + calendarNew.compareTo(calendar));  
}