Java程序运行计时用的

StopWatch stopWatch = new StopWatch();
// 开始时间
stopWatch.start();
stopWatch.stop();
System.out.println("操作成功，执行时长：" + stopWatch.getTime(TimeUnit.SECONDS) + " 秒.");

System.out.println("操作成功，执行时长：" + stopWatch.getSplitTime() + " 毫秒.");