安卓开发：DateUtils

public class DateUtils{
    /**
     * 显示友好时间
     *
     * @param ms
     * @return
     */
    public static String getTimeDes(long ms) {
        int ss = 1000;
        int mi = ss * 60;
        int hh = mi * 60;
        int dd = hh * 24;
        long day = ms / dd;
        long hour = (ms - day * dd) / hh;
        long minute = (ms - day * dd - hour * hh) / mi;
        long second = (ms - day * dd - hour * hh - minute * mi) / ss;
        long milliSecond = ms - day * dd - hour * hh - minute * mi - second
                * ss;
        String str = "";
        if (day > 0) {
            str += day + "天";
        }
        if (hour > 0) {
            str += hour + "小时";
        }
        if (minute > 0) {
            str += minute + "分";
        }
        if (second > 0) {
            str += second + "秒";
        }
        return str;
    }

/**
     *
     * @param beginTime
     * @param _endTime
     * @return  计算两个日期之间相差的天数
     */
    public static double getDecreaseDays(String beginTime, String _endTime) {
        String str1 = beginTime;  //"yyyyMMdd"格式 如 20131022
        String str2 = _endTime;  //"yyyyMMdd"格式 如 20131022
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd");//输入日期的格式
        Date date1 = null;
        try {
            date1 = simpleDateFormat.parse(str1);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Date date2 = null;
        try {
            date2 = simpleDateFormat.parse(str2);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        GregorianCalendar cal1 = new GregorianCalendar();
        GregorianCalendar cal2 = new GregorianCalendar();
        cal1.setTime(date1);
        cal2.setTime(date2);
        double dayCount = (cal2.getTimeInMillis() - cal1.getTimeInMillis()) / (1000 * 3600 * 24);//从间隔毫秒变成间隔天数
        return dayCount;
    }

    /**
     * 计算出endDate之前days天的日期
     *
     * @param endDate
     * @param days
     * @return
     */
    public static String getDate(String endDate, int days) {
        String str1 = endDate;  //"yyyyMMdd"格式 如 20131022
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy/MM/dd");//输入日期的格式
        Date date1 = null;
        try {
            date1 = simpleDateFormat.parse(str1);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Calendar now = Calendar.getInstance();
        now.setTime(date1);
        now.set(Calendar.DATE, now.get(Calendar.DATE) - days);
        Date date = now.getTime();
        return simpleDateFormat.format(date);
    }

}