java得到某年某周的第一天

直接上代码

import java.util.Calendar;import java.util.Date;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;/** * 日期工具类 * @author WXQ * */public class DateUtils {private static final Log log = LogFactory.getLog(DateUtils.class);/**  * 取得当前日期是多少周  *  * @param date  * @return  */public static int getWeekOfYear(Date date) {Calendar c = Calendar.getInstance();c.setFirstDayOfWeek(Calendar.MONDAY);/**设置一年中第一个星期所需的最少天数，例如，如果定义第一个星期包含一年第一个月的第一天，则使用值 1 调用此方法。 * 如果最少天数必须是一整个星期，则使用值 7 调用此方法。 **/c.setMinimalDaysInFirstWeek(1);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 = Calendar.getInstance();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 = Calendar.getInstance();c.set(Calendar.YEAR, year);c.set(Calendar.WEEK_OF_YEAR, week);c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);//设置周一c.setFirstDayOfWeek(Calendar.MONDAY);return c.getTime();}/**  * 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 = Calendar.getInstance();c.set(Calendar.YEAR, year);c.set(Calendar.WEEK_OF_YEAR, week);c.setFirstDayOfWeek(Calendar.MONDAY);c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6); // Sunday return c.getTime();}/**  * 得到某年某月的第一天  *  * @param year  * @param month  * @return  */public static Date getFirstDayOfMonth(int year, int month) {Calendar c = Calendar.getInstance();c.set(Calendar.YEAR, year);c.set(Calendar.MONTH, month-1);c.set(Calendar.DAY_OF_MONTH, c.getActualMinimum(Calendar.DAY_OF_MONTH));return c.getTime();}/**  * 得到某年某月的最后一天  *  * @param year  * @param month  * @return  */public static Date getLastDayOfMonth(int year, int month) {Calendar c = Calendar.getInstance();c.set(Calendar.YEAR, year);c.set(Calendar.MONTH, month-1);c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));return c.getTime();}/** * 得到某年某季度第一天 *  * @param year * @param quarter * @return */public static Date getFirstDayOfQuarter(int year, int quarter) {int month = 0;if (quarter > 4) {return null;} else {month = (quarter - 1) * 3 + 1;}return getFirstDayOfMonth(year, month);}/** * 得到某年某季度最后一天 *  * @param year * @param quarter * @return */public static Date getLastDayOfQuarter(int year, int quarter) {int month = 0;if (quarter > 4) {return null;} else {month = quarter * 3;}return getLastDayOfMonth(year, month);}/** * 得到某年第一天 *  * @param year * @return */public static Date getFirstDayOfYear(int year) {return getFirstDayOfQuarter(year,1);}/** * 得到某年最后一天 *  * @param year * @return */public static Date getLastDayOfYear(int year) {return getLastDayOfQuarter(year,4);}public static void main(String[] args) {log.info(getFirstDayOfWeek(2013,1));log.info(getLastDayOfWeek(2013,1));log.info(getFirstDayOfMonth(2013,2));log.info(getLastDayOfMonth(2013,2));log.info(getFirstDayOfQuarter(2013,2));log.info(getLastDayOfQuarter(2013,2));log.info(getFirstDayOfYear(2013));log.info(getLastDayOfYear(2013));}}

2楼snwrking昨天 15:01

原因找到：这个setMinimalDaysInFirstWeek(7)才是对的

1楼snwrking昨天 14:53

报告一个bug: System.out.println(""+CalendarUtil01.getMaxWeekNumOfYear(2013));n打印出来，结果是1.nn原因我也在查 ~