DB2或MySql的week

package cn.bevis.time; import java.text.SimpleDateFormat; import java.util.Arrays; import java.util.Calendar; import java.util.Date; public class TimeUtil { /** * JAVA的Calendar.WEEK_OF_YEAR与DB2或MySql数据库中week_iso(date)或weekOfYear(date),结果保持一致的方法 * 这样做统计的时候免去很多麻烦，无意中发现的，分享给大家！！！！！！ * 如果有高手，可以帮我解释一下，本人目前还不太清楚！！！，谢谢! * @param date * @return */ public static int[] getWeekOfYear(Date date) {          Calendar calendar = Calendar.getInstance();          //设置周一为一周的第一天        calendar.setFirstDayOfWeek(Calendar.MONDAY);          //这样可以与数据库中weekOfYear保持一致        //Mysql-->weekOfYear(date)//周一为一周的第一天        //DB2-->week_iso(date)//周一为一周的第一天        calendar.setMinimalDaysInFirstWeek(4); //这里设置为4-->原因不详！        calendar.setTime(date);          int week = calendar.get(Calendar.WEEK_OF_YEAR);  

       int year = calendar.get(Calendar.YEAR);

      //如果周次落在最后一周，那么日历向前翻一个月，再去取年份，避免最后一周年份获取有误       if(weekNum == 52 || weekNum == 53 || weekNum == 54){           calendar.add(Calendar.MONTH, -1);           year = calendar.get(Calendar.YEAR);        }

       return new int[]{year,week};      }     public static void main(String[] args) {    for (int i = 0; i < 8; i++) {       Calendar cal = Calendar.getInstance();       cal.set(2015, 11, 28);       cal.add(Calendar.DAY_OF_YEAR, i);       String dateStr = new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());       System.out.println(dateStr); //打印当前日期-->2015-12-28       int[] result = getWeekOfYear(cal.getTime());       System.out.println(Arrays.toString(result)); //打印年份与周次-->[2015, 53]:表示2015年第53周     }   } } //--------打 印 结 果-------> //2015-12-28 //[2015, 53] //2015-12-29 //[2015, 53] //2015-12-30 //[2015, 53] //2015-12-31 //[2015, 53] //2016-01-01 //[2015, 53] //2016-01-02 //[2015, 53] //2016-01-03 //[2015, 53] //2016-01-04

//[2016, 1]

//MySql的结果

SELECT WEEKOFYEAR('2015-12-28') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2015-12-29') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2015-12-30') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2015-12-31') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2016-01-01') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2016-01-02') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2016-01-03') as a FROM DUAL-->53 UNION ALL SELECT WEEKOFYEAR('2016-01-04') as a FROM DUAL-->1