得到今天00:00 的紀元毫秒數

    // Get today 00:00 milliseconds from epoch.
    public static long todayMilliSeconds(TimeZone tz) {
        final Calendar cal = Calendar.getInstance(tz);
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DATE), 0, 0, 0);
        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTimeInMillis();
    }

    // Get today 23:59 milliseconds from epoch.
    public static long todayEndMilliSeconds(TimeZone tz){
        final Calendar cal = Calendar.getInstance(tz);
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DATE) + 1, 0, 0, 0);
        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTimeInMillis();
    }

    public static TimeZone timeZone(){
        String timeZoneId = "RPC";
        return TimeZone.getTimeZone(timeZoneId);
    }

    public static String timeString(long milliseconds){
        Date date = new Date(milliseconds);
        SimpleDateFormat formater = new SimpleDateFormat("yyyy年MM月dd日 HH:mm");
        return formater.format(date);
    }