一些关于时间常用的java代码

    /**
     * 输入Date  和 + - 数字代表天数  进行计算出需要的Date
     * @param date
     * @param day
     * @return
     * @throws ParseException
     */
    public static Date addDate(Date date, long day) throws ParseException {
        long time = date.getTime(); // 得到指定日期的毫秒数
        day = day * 24 * 60 * 60 * 1000; // 要加上的天数转换成毫秒数
        time += day; // 相加得到新的毫秒数
        // time -= day; // 相减得到新的毫秒数
        return new Date(time); // 将毫秒数转换成日期
    }

        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd"); // 日期格式
        Date start = null;
        Date end = null;
        if (!e.isEmpty()||!s.isEmpty()){
            start = dateFormat.parse(s);
            end = dateFormat.parse(e);
        }

两个搭配使用，判断两个Date时间相距的年份，给个小例子

hotLawyer.setTime("执业"+yearCompare(lawyerDO.getMajor(),new Date())+"年");

    /**
     * 计算2个日期之间相差的  相差多少年月日
     * 比如：2011-02-02 到  2017-03-02 相差 6年，1个月，0天
     * @param fromDate
     * @param toDate
     * @return
     */
    public static DayCompare dayComparePrecise(Date fromDate, Date toDate){
        Calendar  from  =  Calendar.getInstance();
        from.setTime(fromDate);
        Calendar  to  =  Calendar.getInstance();
        to.setTime(toDate);
        int fromYear = from.get(Calendar.YEAR);
        int fromMonth = from.get(Calendar.MONTH);
        int fromDay = from.get(Calendar.DAY_OF_MONTH);
        int toYear = to.get(Calendar.YEAR);
        int toMonth = to.get(Calendar.MONTH);
        int toDay = to.get(Calendar.DAY_OF_MONTH);
        int year = toYear  -  fromYear;
        int month = toMonth  - fromMonth;
        int day = toDay  - fromDay;
        DayCompare dayCompare = new DayCompare();
        dayCompare.setDay(day);
        dayCompare.setMonth(month);
        dayCompare.setYear(year);
        return dayCompare;
    }

    public static String yearCompare(Date fromDate,Date toDate){
        DayCompare result = dayComparePrecise(fromDate, toDate);
        double month = result.getMonth();
        double year = result.getYear();
        //返回2位小数，并且四舍五入
        DecimalFormat df = new DecimalFormat("######0");
        return df.format(year + month / 12);
    }

public  class DayCompare {
    private int year;
    private int month;
    private int day;

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }

    public int getMonth() {
        return month;
    }

    public void setMonth(int month) {
        this.month = month;
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
    }
}