米国サーバーの計算時間に1時間の差がある

//beginDate = '2013-03-06 00:00:00'
//endDate = '2013-03-08 00:00:00'
	public static int intervalDay(String beginDate,String endDate){
		DateFormat dfs1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		DateFormat dfs2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date begin = null;
		Date end = null;
		try {
			begin = dfs1.parse(beginDate);
			end = dfs2.parse(endDate);
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		long a = end.getTime()/1000;
                //     end.getTime() 1363615810000 || '2013-03-18 12:00:00'

		long b = begin.getTime()/1000;
                //     begin.getTime() 1362546000000 || '2013-03-06 13:00:00'

		long between = (a-b);//  1000       
		int day = (int) (between/(24*3600));
		return day;
	}

中国の計算間隔は12アメリカの計算で11