使用Calendar類進行日期處理

1.獲取指定年月日及設置指定時間

int year = Integer.parseInt(new SimpleDateFormat("yyyy").format(time));
int month = Integer.parseInt(new SimpleDateFormat("MM").format(time));
int day = Integer.parseInt(new SimpleDateFormat("dd").format(time));
Calendar calendar = Calendar.getInstance();
calendar.set(year, month - 1, day,17,30);
Calendar calendar1 = Calendar.getInstance();
calendar1.set(year, month - 1, day,18,30);

//時間插入

calendar.getTime();

2.獲取當天最大時間（yyyyMMdd 23:59:59）

  private static Date getEndOfDay(Date date) {
    LocalDateTime localDateTime = LocalDateTime
        .ofInstant(Instant.ofEpochMilli(date.getTime()), ZoneId.systemDefault());;
    LocalDateTime endOfDay = localDateTime.with(LocalTime.MAX);
    return Date.from(endOfDay.atZone(ZoneId.systemDefault()).toInstant());
  }

3.日期格式化

SimpleDateFormat Format = new SimpleDateFormat("yyyy-MM-dd");
Date datetime = Format.parse(date);

4.獲取指定日期月份第一天和最后一天

//獲取本月第一天 
SimpleDateFormat sf=new SimpleDateFormat("MM-dd");
GregorianCalendar gcLast=(GregorianCalendar)Calendar.getInstance();
gcLast.setTime(time);
gcLast.set(Calendar.DAY_OF_MONTH, 1);
String firstDay = sf.format(gcLast.getTime());

//獲取本月最后一天
Calendar calendar=Calendar.getInstance();
calendar.setTime(time);
calendar.add(Calendar.DATE, -1);
calendar.set(Calendar.DATE, calendar.getActualMaximum(calendar.DATE));
String endDay = sf.format(calendar.getTime());

5.獲取指定日期的周一日期與周五日期

 

Calendar calendar = Calendar.getInstance();
calendar.setTime(createDate);

 //判斷要計算的日期是否是周日，如果是則減一天計算周六的，否則會出問題，計算到下一周去了
int dayWeek = calendar.get(Calendar.DAY_OF_WEEK);//獲得當前日期是一個星期的第幾天
if(1 == dayWeek) {
  calendar.add(Calendar.DAY_OF_MONTH, -1);
}
calendar.setFirstDayOfWeek(Calendar.MONDAY);//設置一個星期的第一天，按中國的習慣一個星期的第一天是星期一

int day = calendar.get(Calendar.DAY_OF_WEEK);//獲得當前日期是一個星期的第幾天
calendar.add(Calendar.DATE, calendar.getFirstDayOfWeek()-day);//根據日歷的規則，給當前日期減去星期幾與一個星期第一天的差值
String starDay = sdf.format(calendar.getTime());
calendar.add(Calendar.DATE, 4);
String endDay = sdf.format(calendar.getTime());

6.獲取當前年份，月份，日期，小時，分鍾，秒等

Calendar cale = Calendar.getInstance();
int year = cale.get(Calendar.YEAR);           //年份
int nowMonth = cale.get(Calendar.MONTH) + 1;  //月份
int day = cale.get(Calendar.DATE);            //日期
int hour = cale.get(Calendar.HOUR_OF_DAY);    //小時 24小時制
int hour = cale.get(Calendar.Hour)　　　　　　　//小時 12小時制
int minute = cale.get(Calendar.MINUTE);       //分鍾
int second = cale.get(Calendar.SECOND);       //秒
int dayOfWeek = cale.get(Calendar.DAY_OF_WEEK);     //一周第幾天
int dayOfMonth = cale.get(Calendar.DAY_OF_MONTH);    //一月第幾天
int dayOfYear = cale.get(Calendar.DAY_OF_YEAR);     //一年第幾天