根据时间得到该年第几周和根据周得到时间区间

根据时间得到该时间是该年第几周：
select to_number(to_char(to_date('2010-01-12 00:00:00','yyyy-mm-dd hh24:mi:ss'),'FMWW')) from dual;
2010年1月12日属于2010年第2周
select to_number(to_char((sysdate),'FMWW')) from dual;
判断当前时间属于当前年第几周
以上情况只是把每年的1月1日作为第一天，如同这个oracle语句的效果：
select to_char(sysdate,'iw') from dual
按照国际标准是吧每年第一周的星期一作为这一年的开头：
select to_char(sysdate,'ww') from dual

根据第几周的到时间区间:
1>A跨年：
DateFormat df=new SimpleDateFormat("yyyy-MM-dd");
Calendar calFirstDayOfTheYear = new GregorianCalendar(2010,
    Calendar.JANUARY, 1);
calFirstDayOfTheYear.add(Calendar.DATE, 7 * (5-1));
   
int dayOfWeek = calFirstDayOfTheYear.get(Calendar.DAY_OF_WEEK);
   
Calendar calFirstDayInWeek = (Calendar)calFirstDayOfTheYear.clone();
calFirstDayInWeek.add(Calendar.DATE,
calFirstDayOfTheYear.getActualMinimum(Calendar.DAY_OF_WEEK) - dayOfWeek);
Date firstDayInWeek = calFirstDayInWeek.getTime();
System.out.println(2010 + "年第" + 5 + "周的第一天是" + df.format(firstDayInWeek));
   
Calendar calLastDayInWeek = (Calendar)calFirstDayOfTheYear.clone();
calLastDayInWeek.add(Calendar.DATE,
calFirstDayOfTheYear.getActualMaximum(Calendar.DAY_OF_WEEK) - dayOfWeek);
Date lastDayInWeek = calLastDayInWeek.getTime();
System.out.println(2010 + "年第" + 5 + "周的第一天是" + df.format(lastDayInWeek));

-----------------------------
2010年第5周的第一天是2010-01-24
2010年第5周的最后一天是2010-01-30

1>B跨年：
DateFormat df=new SimpleDateFormat("yyyy-MM-dd");
int x=2010;
int n=53;
Calendar cal = new GregorianCalendar(x, Calendar.JANUARY, 1);

int ff=cal.get(Calendar.DAY_OF_WEEK);
int week=cal.get(Calendar.WEEK_OF_YEAR);
System.out.println("week:"+week);
System.out.println("ff:"+ff);
switch(ff){
case 1:
cal.set(Calendar.DATE,7*(n-2)+ff+7);
break;
case 2:
cal.set(Calendar.DATE,7*(n-2)+ff+6);
break;
case 3:
cal.set(Calendar.DATE,7*(n-2)+ff+5);
break;
case 4:
cal.set(Calendar.DATE,7*(n-2)+ff+4);
break;
case 5:
cal.set(Calendar.DATE,7*(n-2)+ff+3);
break;
case 6:
cal.set(Calendar.DATE,7*(n-2)+ff+2);
break;
case 7:
cal.set(Calendar.DATE,7*(n-2)+ff+1);
break;

}

System.out.println("cal 1:"+df.format(cal.getTime()));
int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
System.out.println("dayOfWeek :"+dayOfWeek);
Calendar calFirstDayInThisWeek = (Calendar) cal.clone();
calFirstDayInThisWeek.add(Calendar.DATE, cal.getActualMinimum(Calendar.DAY_OF_WEEK)-dayOfWeek);
Calendar calLastDayInThisWeek = (Calendar) cal.clone();
calLastDayInThisWeek.add(Calendar.DATE,cal.getActualMaximum(Calendar.DAY_OF_WEEK)-dayOfWeek);
Date startDate=calFirstDayInThisWeek.getTime();
Date endDate=calLastDayInThisWeek.getTime();
System.out.println("calFirstDayInThisWeek:"+df.format(calFirstDayInThisWeek.getTime()));
System.out.println("calLastDayInThisWeek:"+df.format(calLastDayInThisWeek.getTime()));
System.out.println("startDate:"+df.format(startDate.getTime()));

---------------------------------
week:1
ff:6
cal 1:2010-12-31
dayOfWeek :6
calFirstDayInThisWeek:2010-12-26
calLastDayInThisWeek:2011-01-01
startDate:2010-12-26

2>不跨年：
long ONEDATE = 1000l * 3600 * 24;
SimpleDateFormat format = new SimpleDateFormat( "yyyy-MM-dd ");
Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.set(Calendar.YEAR, 2005);

//最后一周
cal.set(Calendar.DAY_OF_YEAR, cal.getActualMaximum(Calendar.DAY_OF_YEAR));
Date end = cal.getTime();

cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
Date start = cal.getTime();

System.out.print( "2005年最后一周区间: " + format.format(start));
System.out.println( "-- " + format.format(end) + " 共 " + ((end.getTime() - start.getTime()) / ONEDATE + 1) + "天 ");


//第一周
cal.set(Calendar.DAY_OF_YEAR, 1);
cal.set(Calendar.YEAR, 2006);
start = cal.getTime();

cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
end = cal.getTime();

System.out.print( "2006年第一周区间: " + format.format(start));
System.out.println( "-- " + format.format(end) + " 共 " + ((end.getTime() - start.getTime()) / ONEDATE + 1) + "天 ");

//第N周
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);//需要先设置星期
cal.set(Calendar.WEEK_OF_YEAR, 20);

start = cal.getTime();

cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
end = cal.getTime();

System.out.print( "2006年第20周区间: " + format.format(start));
System.out.println( "-- " + format.format(end) + " 共 " + ((end.getTime() - start.getTime()) / ONEDATE + 1) + "天 ");

--------------------------------------
2005年最后一周区间: 2005-12-26 -- 2005-12-31  共 6天
2006年第一周区间: 2006-01-01 -- 2006-01-01  共 1天
2006年第20周区间: 2006-05-08 -- 2006-05-14  共 7天

PS:非原创,素材来自网络.

评论

2 楼 江米小枣 2010-11-12  

dk101 写道

你这个总结得很详细了。以后使用时，直接在这儿查找就可以了。

呵呵 有的地方还不是很精确。

1 楼 dk101 2010-11-09  

你这个总结得很详细了。以后使用时，直接在这儿查找就可以了。