Calendar GregorianCalendar

╰半夏微凉° 2022-07-12 15:24 144阅读 0赞

GregorianCalendar is a concrete subclass of `Calendar` and provides the standard calendar system used by most of the world.

public abstract class Calendar 说明calendar类是一个抽象类，从javadoc中可看出来，GregorianCalendar应该是Calendar类的唯一实现类了。

Date类中，多数的方法都已经成为Deprecated，所以，我们在使用的时候，可以用Calendar类来设置好我们需要的时间之后，用Calendar类的gettime方法来取得这个Date对象。

import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar; public class WeekUtil \{ /\*\* \* 取得当前日期是多少周 \* \* @param date \* @return \*/ public static int getWeekOfYear(Date date) \{ Calendar c = new GregorianCalendar(); c.setFirstDayOfWeek(Calendar.MONDAY); c.setMinimalDaysInFirstWeek(7); c.setTime(date); return c.get(Calendar.WEEK\_OF\_YEAR); \} /\*\* \* 得到某一年周的总数 \* \* @param year \* @return \*/ public static int getMaxWeekNumOfYear(int year) \{ Calendar c = new GregorianCalendar(); c.set(year, Calendar.DECEMBER, 31, 23, 59, 59); return getWeekOfYear(c.getTime()); \} /\*\* \* 得到某年某周的第一天 \* \* @param year \* @param week \* @return \*/ public static Date getFirstDayOfWeek(int year, int week) \{ Calendar c = new GregorianCalendar(); c.set(Calendar.YEAR, year); c.set(Calendar.MONTH, Calendar.JANUARY); c.set(Calendar.DATE, 1); Calendar cal = (GregorianCalendar) c.clone(); p(c.getTime()); cal.add(Calendar.DATE, week \* 7); return getFirstDayOfWeek(cal.getTime()); \} public static void p(Object o) \{ System.out.println(o); \} /\*\* \* 得到某年某周的最后一天 \* \* @param year \* @param week \* @return \*/ public static Date getLastDayOfWeek(int year, int week) \{ Calendar c = new GregorianCalendar(); c.set(Calendar.YEAR, year); c.set(Calendar.MONTH, Calendar.JANUARY); c.set(Calendar.DATE, 1); Calendar cal = (GregorianCalendar) c.clone(); cal.add(Calendar.DATE, week \* 7); return getLastDayOfWeek(cal.getTime()); \} /\*\* \* 取得当前日期所在周的第一天 \* \* @param date \* @return \*/ public static Date getFirstDayOfWeek(Date date) \{ Calendar c = new GregorianCalendar(); c.setFirstDayOfWeek(Calendar.MONDAY); c.setTime(date); c.set(Calendar.DAY\_OF\_WEEK, c.getFirstDayOfWeek()); // Monday return c.getTime(); \} /\*\* \* 取得当前日期所在周的最后一天 \* \* @param date \* @return \*/ public static Date getLastDayOfWeek(Date date) \{ Calendar c = new GregorianCalendar(); c.setFirstDayOfWeek(Calendar.MONDAY); c.setTime(date); c.set(Calendar.DAY\_OF\_WEEK, c.getFirstDayOfWeek() + 6); // Sunday return c.getTime(); \} \}