Hibernate Calendar API

java.util.Calendar

Calendar 的 month 從 0 開始，也就是全年 12 個月由 0 ~ 11 進行表示。
Calendar.DAY_OF_WEEK 定義和值如下：

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

SimpleDateFormat 的格式定義

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
-------------------------------------------------------------------------------

Java Calendar 演示代碼如下

import java.util.Date;  
import java.text.SimpleDateFormat;  
import java.text.DateFormat;  
import java.text.ParseException;  
import java.util.Calendar;  

public class Test  
{  
  public Test()  
  {  
  }  

  public static void main(String[] args)  
  {  
    // 字符串轉換日期格式  
    // DateFormat fmtDateTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
    // 接收傳入參數  
    // String strDate = args[1];  
    // 得到日期格式對象  
    // Date date = fmtDateTime.parse(strDate);  

    // 完整顯示今天日期時間  
    String str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS")).format(new Date());  
    System.out.println(str);  

    // 創建 Calendar 對象  
    Calendar calendar = Calendar.getInstance();  

    try  
    {  
      // 對 calendar 設置時間的方法  
      // 設置傳入的時間格式  
      SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-M-d H:m:s");  
      // 指定一個日期  
      Date date = dateFormat.parse("2013-6-1 13:24:16");  
      // 對 calendar 設置爲 date 所定的日期  
      calendar.setTime(date);  

      // 按特定格式顯示剛設置的時間  
      str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS")).format(calendar.getTime());  
      System.out.println(str);  
    }  
    catch (ParseException e)  
    {  
      e.printStackTrace();  
    }  

    // 或者另一種設置 calendar 方式  
    // 分別爲 year, month, date, hourOfDay, minute, second  
    calendar = Calendar.getInstance();  
    calendar.set(2013, 1, 2, 17, 35, 44);  
    str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS")).format(calendar.getTime());  
    System.out.println(str);  

    // Calendar 取得當前時間的方法  
    // 初始化 (重置) Calendar 對象  
    calendar = Calendar.getInstance();  
    // 或者用 Date 來初始化 Calendar 對象  
    calendar.setTime(new Date());  

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

    str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS")).format(calendar.getTime());  
    System.out.println(str);  

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

    // 顯示月份 (從0開始, 實際顯示要加一)  
    int month = calendar.get(Calendar.MONTH);  
    System.out.println("nth is = " + (month + 1));  

    // 本週幾  
    int week = calendar.get(Calendar.DAY_OF_WEEK);  
    System.out.println("week is = " + week);  

    // 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小時以後  
    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);  

    // 當前分鐘數  
    int MINUTE = calendar.get(Calendar.MINUTE);  
    System.out.println("MINUTE = " + MINUTE);  

    // 15 分鐘以後  
    calendar.add(Calendar.MINUTE, 15);  
    MINUTE = calendar.get(Calendar.MINUTE);  
    System.out.println("MINUTE + 15 = " + MINUTE);  

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

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

    // 重置 Calendar 顯示當前時間  
    calendar.setTime(new Date());  
    str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS")).format(calendar.getTime());  
    System.out.println(str);  

    // 創建一個 Calendar 用於比較時間  
    Calendar calendarNew = Calendar.getInstance();  

    // 設定爲 5 小時以前，後者大，顯示 -1  
    calendarNew.add(Calendar.HOUR, -5);  
    System.out.println("時間比較：" + calendarNew.compareTo(calendar));  

    // 設定7小時以後，前者大，顯示 1  
    calendarNew.add(Calendar.HOUR, +7);  
    System.out.println("時間比較：" + calendarNew.compareTo(calendar));  

    // 退回 2 小時，時間相同，顯示 0  
    calendarNew.add(Calendar.HOUR, -2);  
    System.out.println("時間比較：" + calendarNew.compareTo(calendar));  
  }  
}  

要計算時間差，可用 Calendar.getTimeInMillis() 取得兩個時間的微秒級的時間差，再加以換算即可，比如獲得相差天數，代碼如下：

long val = calendarEnd.getTimeInMillis() - calendarBegin.getTimeInMillis();  
// 換算後得到天數  
long day = val / (1000 * 60 * 60 * 24); 

使用hibernate映射Calendar