逛别人博客改自己代码，我只是个代码搬运工，用到业务场景获取当年后4周的周数，以及选择其中某个周 获取周对应开始结束日期，通业务场景网上找代码麻烦，所以方便其他兄弟，贴出全部代码如下：
public class WeekUtils {
public static void main(String[] args)
{
System.out.println(getWeekAndYear("2020-06-16"));
System.out.println(getStartDayOfWeekNo(2020,53));
System.out.println(getEndDayOfWeekNo(2020,53));
getWeeksAndYear(2020,25,1);
getWeeksAndYear("2020-12-31",4);
System.out.println(getDateByYearweek("20212"));
}
/**
* 当前日期所在一年中的第几周
* @param date
* @return
*/
public static MapgetWeekAndYear(String date) {
Map result =new HashMap();
Calendar cal = Calendar.getInstance();
//设置一周的开始,默认是周日,这里设置成星期一
cal.setFirstDayOfWeek(Calendar.MONDAY);
SimpleDateFormat format =new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat formatMon =new SimpleDateFormat("MM");
SimpleDateFormat formatYear =new SimpleDateFormat("yyyy");
Date d =null;
try {
d = format.parse(date);
}catch (ParseException e) {
e.printStackTrace();
}
cal.setTime(d);
int month = Integer.valueOf(formatMon.format(d));
int year = Integer.valueOf(formatYear.format(d));
int week = cal.get(Calendar.WEEK_OF_YEAR);
result.put("week", week);
if(week ==1 && month ==12){
result.put("year", year +1);
}else{
result.put("year", year);
}
return result;
}
/**
* 某个日期所在年周 偏移量是指获取多少个年周
* @param date
* @param offset
* @return
*/
public static ListgetWeeksAndYear(String date, int offset) {
if(StringUtils.isBlank(date))
{
date = DateUtils.format(new Date());
}
Calendar cal = Calendar.getInstance();
//设置一周的开始,默认是周日,这里设置成星期一
cal.setFirstDayOfWeek(Calendar.MONDAY);
SimpleDateFormat format =new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat formatMon =new SimpleDateFormat("MM");
SimpleDateFormat formatYear =new SimpleDateFormat("yyyy");
Date d =null;
try {
d = format.parse(date);
}catch (ParseException e) {
e.printStackTrace();
}
cal.setTime(d);
int month = Integer.valueOf(formatMon.format(d));
int year = Integer.valueOf(formatYear.format(d));
int week = cal.get(Calendar.WEEK_OF_YEAR);
if(week ==1 && month ==12){
year = year +1;
}
Calendar cal1 =getCalendarFormYear(year);
List ywList =new ArrayList<>();
for(int i =1 ;i<= offset;i++)
{
cal1.set(Calendar.WEEK_OF_YEAR, week + i);
int jsweek = cal1.get(Calendar.WEEK_OF_YEAR);
int jsyear = cal1.get(Calendar.YEAR);
//System.out.println("item:"+jsyear+""+jsweek);
String sjyw = jsyear+""+jsweek;
ywList.add(sjyw);
}
return ywList;
}
/**
* 根据年周查询对应的周一和周日的日期
* @param yearweek
* @return
*/
public static ListgetDateByYearweek(String yearweek){
String year = yearweek.substring(0,4);
String weekno = yearweek.substring(4,yearweek.length());
List dateList =new ArrayList<>();
String startDateStr =getStartDayOfWeekNo(Integer.parseInt(year),Integer.parseInt(weekno));
String endDateStr =getEndDayOfWeekNo(Integer.parseInt(year),Integer.parseInt(weekno));
dateList.add(startDateStr);
dateList.add(endDateStr);
return dateList;
}
/**
* 获取某年某周后多少周是第几周
* @param year
* @param weekno
* @param offset
*/
public static void getWeeksAndYear(int year, int weekno, int offset) {
Calendar cal =getCalendarFormYear(year);
cal.set(Calendar.WEEK_OF_YEAR, weekno + offset);
int week = cal.get(Calendar.WEEK_OF_YEAR);
int jsyear = cal.get(Calendar.YEAR);
System.out.println(jsyear+""+week);
}
/**
* get Calendar of given year
* @param year
* @return
*/
private static CalendargetCalendarFormYear(int year){
Calendar cal = Calendar.getInstance();
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
cal.set(Calendar.YEAR, year);
return cal;
}
/**
* get start date of given week no of a year
* @param year
* @param weekNo
* @return
*/
public static StringgetStartDayOfWeekNo(int year,int weekNo){
Calendar cal =getCalendarFormYear(year);
cal.set(Calendar.WEEK_OF_YEAR, weekNo);
return cal.get(Calendar.YEAR) +"-" + (cal.get(Calendar.MONTH) +1) +"-" +
cal.get(Calendar.DAY_OF_MONTH);
}
/**
* get the end day of given week no of a year.
* @param year
* @param weekNo
* @return
*/
public static StringgetEndDayOfWeekNo(int year,int weekNo){
Calendar cal =getCalendarFormYear(year);
cal.set(Calendar.WEEK_OF_YEAR, weekNo);
cal.add(Calendar.DAY_OF_WEEK, 6);
return cal.get(Calendar.YEAR) +"-" + (cal.get(Calendar.MONTH) +1) +"-" +
cal.get(Calendar.DAY_OF_MONTH);
}