java如何实现显示当前运行时间

/**
	 * 
	 * @author wxy
	 * @param ctime
	 *            时间
	 * @param format
	 *            格式 格式描述:例如:yyyy-MM-dd yyyy-MM-dd HH:mm:ss
	 * @return
	 */
	public static String showTime(Date ctime, String format) {
		//System.out.println("当前时间是："+new Timestamp(System.currentTimeMillis()));
		
 
		//System.out.println("发布时间是："+df.format(ctime).toString());
		String r = "";
		if(ctime==null)return r;
		if(format==null)format="MM-dd HH:mm";
 
		long nowtimelong = System.currentTimeMillis();
 
		long ctimelong = ctime.getTime();
		long result = Math.abs(nowtimelong - ctimelong);
 
		if(result < 60000){// 一分钟内
			long seconds = result / 1000;
			if(seconds == 0){
				r = "刚刚";
			}else{
				r = seconds + "秒前";
			}
		}else if (result >= 60000 && result < 3600000){// 一小时内
			long seconds = result / 60000;
			r = seconds + "分钟前";
		}else if (result >= 3600000 && result < 86400000){// 一天内
			long seconds = result / 3600000;
			r = seconds + "小时前";
		}else if (result >= 86400000 && result < 1702967296){// 三十天内
			long seconds = result / 86400000;
			r = seconds + "天前";
		}else{// 日期格式
			format="MM-dd HH:mm";
			SimpleDateFormat df = new SimpleDateFormat(format);
			r = df.format(ctime).toString();
		}
		return r;
	}

public static void main(String[] args) {
try{
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println(showTime(df.parse("2015-02-27 11:31:00"),"yyyy-MM-dd HH:mm:ss"));
}catch (Exception e) {
// TODO: handle exception
}
}