java 代码碎片2 —— 关于日期

一、日期相关

public static Date getBeginDayOfWeek() {
    Date date = new Date();
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
    if (dayofweek == 1) {
        dayofweek += 7;
    }
    cal.add(Calendar.DATE, 2 - dayofweek);
    return getDayStartTime(cal.getTime());
}
 
// 获取本周的结束时间
public static Date getEndDayOfWeek() {
    Calendar cal = Calendar.getInstance();
    cal.setTime(getBeginDayOfWeek());
    cal.add(Calendar.DAY_OF_WEEK, 6);
    Date weekEndSta = cal.getTime();
    return getDayEndTime(weekEndSta);
}
    
public static Timestamp getDayEndTime(Date d) {
    Calendar calendar = Calendar.getInstance();
    if (null != d)
        calendar.setTime(d);
    calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
            calendar.get(Calendar.DAY_OF_MONTH), 23, 59, 59);
    calendar.set(Calendar.MILLISECOND, 999);
    return new Timestamp(calendar.getTimeInMillis());
}
    
public static Timestamp getDayStartTime(Date d) {
    Calendar calendar = Calendar.getInstance();
    if (null != d)
        calendar.setTime(d);
    calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
            calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
    calendar.set(Calendar.MILLISECOND, 0);
    return new Timestamp(calendar.getTimeInMillis());
}
    
public static Date getBeginDayOfMonth() {
    Calendar calendar = Calendar.getInstance();
    calendar.set(getNowYear(), getNowMonth() - 1, 1);
    return getDayStartTime(calendar.getTime());
}
 
// 获取本月的结束时间
public static Date getEndDayOfMonth() {
    Calendar calendar = Calendar.getInstance();
    calendar.set(getNowYear(), getNowMonth() - 1, 1);
    int day = calendar.getActualMaximum(5);
    calendar.set(getNowYear(), getNowMonth() - 1, day);
    return getDayEndTime(calendar.getTime());
}
    
// 获取今年是哪一年
public static Integer getNowYear() {
    Date date = new Date();
    GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
    gc.setTime(date);
    return Integer.valueOf(gc.get(1));
}
 
// 获取本月是哪一月
public static int getNowMonth() {
    Date date = new Date();
    GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
    gc.setTime(date);
    return gc.get(2) + 1;
}