java周数与相应时间转换实体类

港控/mmm° 2022-05-19 04:22 242阅读 0赞

## 前言 ##

最近开发遇到查询第几周内数据的问题，从而计算环比、同比，这就需要知道周数对应的日期，上网搜索并总结出一个实体类，方便以后开发。

## 具体代码 ##

import java.text.SimpleDateFormat;
    import java.time.YearMonth;
    import java.time.temporal.ChronoUnit;
    import java.util.Calendar;
    import java.util.Date;
    import java.util.GregorianCalendar;
    
    public class DateUtil { 
    
         /** * 取得当前日期是多少周 * * @param date * @return */
         public 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 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（yyyy） * @param week * @return */
         public String getFirstDayOfWeek(String year, String week) {
             Calendar c = new GregorianCalendar();
             c.set(Calendar.YEAR, Integer.valueOf(year));
             c.set (Calendar.MONTH, Calendar.JANUARY);
             c.set(Calendar.DATE, 1);
    
             Calendar cal = (GregorianCalendar) c.clone();
             cal.add(Calendar.DATE, (Integer.valueOf(week)-1) * 7);
    
             return getFirstDayOfWeek(cal.getTime());
         }
    
         /** * 得到某年某周的最后一天 * * @param year(yyyy) * @param week * @return */
         public String getLastDayOfWeek(String year, String week) {
             Calendar c = new GregorianCalendar();
             c.set(Calendar.YEAR, Integer.valueOf(year));
             c.set(Calendar.MONTH, Calendar.JANUARY);
             c.set(Calendar.DATE, 1);
    
             Calendar cal = (GregorianCalendar) c.clone();
             cal.add(Calendar.DATE , (Integer.valueOf(week)-1) * 7);
    
             return getLastDayOfWeek(cal.getTime());
         }
         /** * 得到某年前一年某周的第一天 * * @param year(yyyy) * @param week * @return */
         public String getLastYearFirstDayOfWeek(String year, String week) {
             Calendar c = new GregorianCalendar();
             c.set(Calendar.YEAR, Integer.valueOf(year)-1);
             c.set (Calendar.MONTH, Calendar.JANUARY);
             c.set(Calendar.DATE, 1);
    
             Calendar cal = (GregorianCalendar) c.clone();
             cal.add(Calendar.DATE, (Integer.valueOf(week)-1) * 7);
    
             return getFirstDayOfWeek(cal.getTime ());
         }
    
         /** * 得到某年前一年某周的最后一天 * * @param year(yyyy) * @param week * @return */
         public String getLastYearLastDayOfWeek(String year, String week) {
             Calendar c = new GregorianCalendar();
             c.set(Calendar.YEAR, Integer.valueOf(year)-1);
             c.set(Calendar.MONTH, Calendar.JANUARY);
             c.set(Calendar.DATE, 1);
    
             Calendar cal = (GregorianCalendar) c.clone();
             cal.add(Calendar.DATE , (Integer.valueOf(week)-1) * 7);
    
             return getLastDayOfWeek(cal.getTime());
         }
    
         /** * 取得指定日期所在周的第一天 * * @param date * @return String(yyyyMMdd) */
         public String getFirstDayOfWeek(Date date) {
             SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
             Calendar c = new GregorianCalendar();
             c.setFirstDayOfWeek(Calendar.MONDAY);
             c.setTime(date);
             c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek()); // Monday
             return sdf.format(c.getTime());
         }
    
         /** * 取得指定日期所在周的最后一天 * * @param date * @return String(yyyyMMdd) */
         public String getLastDayOfWeek(Date date) {
             SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
             Calendar c = new GregorianCalendar();
             c.setFirstDayOfWeek(Calendar.MONDAY);
             c.setTime(date);
             c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6); // Sunday
             return sdf.format(c.getTime());
         }
    
         /** * 取得当前日期所在周的第一天 * * @return */
         public Date getFirstDayOfWeek() {
             Calendar c = new GregorianCalendar();
             c.setFirstDayOfWeek(Calendar.MONDAY);
             c.setTime(new 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 * * @return */
         public Date getLastDayOfWeek() {
             Calendar c = new GregorianCalendar();
             c.setFirstDayOfWeek(Calendar.MONDAY);
             c.setTime(new Date());
             c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6); // Sunday
             return c.getTime();
         }
    
         /** * 获取指定月所在的最后一天 */
         public String getLastDayOfMonth(String year,String month) {  
             SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
             Calendar cal = Calendar.getInstance();  
             cal.set(Calendar.YEAR,Integer.valueOf(year));  
             cal.set(Calendar.MONTH, Integer.valueOf(month)-1);  
             int lastDay = cal.getActualMaximum(Calendar.DAY_OF_MONTH);  
             cal.set(Calendar.DAY_OF_MONTH, lastDay);  
             return sdf.format(cal.getTime());  
        }  
    
         /** * 获取指定月前一个月所在的最后一天 */
         public String getLastMonthLastDayOfMonth(String year,String month) {  
             YearMonth yearMonth = YearMonth.parse(year+"-"+month);
             String s=yearMonth.minus(1, ChronoUnit.MONTHS).toString();
             String[] arr = s.split("-");
             SimpleDateFormat sdf1 = new SimpleDateFormat("yyyyMMdd");
             Calendar cal = Calendar.getInstance();  
             cal.set(Calendar.YEAR,Integer.valueOf(arr[0]));  
             cal.set(Calendar.MONTH, Integer.valueOf(arr[1])-1);  
             int lastDay = cal.getActualMaximum(Calendar.DAY_OF_MONTH);  
             cal.set(Calendar.DAY_OF_MONTH, lastDay);  
             return sdf1.format(cal.getTime());  
        }  
         /** * 获取指定日期对应去年的这天 * @param day(yyyyMMdd) */
        public String getNowOfLastYear(String day) {
            return String.valueOf(Integer.parseInt(day.substring(0,4)) - 1)+day.substring(4,day.length());
        }
    
        /** * 获得指定日期的前一天 * @param day(yyyyMMdd) * @return * @throws Exception */ 
        public String getLastDayOfDay(String day){ 
            Calendar c = Calendar.getInstance(); 
            Date date=null; 
            try { 
                date = new SimpleDateFormat("yyyyMMdd").parse(day); 
            } catch (Exception e) { 
                e.printStackTrace(); 
            } 
            c.setTime(date); 
            int day=c.get(Calendar.DATE); 
            c.set(Calendar.DATE,day-1); 
    
            String dayBefore=new SimpleDateFormat("yyyyMMdd").format(c.getTime()); 
            return dayBefore; 
        } 
    
    }

## 后记 ##

实际运用可以调整传入参数的类型，和返回值的类型，方便开发。