java_获取某月开始和结束时间

1、获取某月的开始时间

public static Date getBeginDayOfMonth(String date) {
    LocalDate date2;
    if (null==date){
        date2=LocalDate.now();
    }else {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        date2=LocalDate.parse(date, fmt);
    }
    Calendar calendar = Calendar.getInstance();
    calendar.set(date2.getYear(), date2.getMonthValue()-1, 1);
    return getDayStartTime(calendar.getTime());
}

2、获取某月的结束时间

public static Date getEndDayOfMonth(String date) {
    LocalDate date2;
    if (null==date){
        date2=LocalDate.now();
    }else {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        date2=LocalDate.parse(date, fmt);
    }
    Calendar calendar = Calendar.getInstance();
    calendar.set(date2.getYear(), date2.getMonthValue()-1, 1);
    int day = calendar.getActualMaximum(5);
    calendar.set(date2.getYear(), date2.getMonthValue()-1, day);
    return getDayEndTime(calendar.getTime());
}

3、公共方法

//获取某个日期的开始时间
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());
}
//获取某个日期的结束时间
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());
}