记录程序耗时

说明：用 spring 自身提供的 stopWatch API

    @Test
    public void test01() throws InterruptedException {
        StopWatch watch = new StopWatch();
        watch.start("任务一");
        Thread.sleep(3000);
        watch.stop();
        System.out.println("任务名称：" + watch.getLastTaskName() + ",耗时：" + watch.getLastTaskTimeMillis());
        watch.start("任务二");
        Thread.sleep(1000);
        watch.stop();
        System.out.println("任务名称：" + watch.getLastTaskName() + ",耗时：" + watch.getLastTaskTimeMillis());
　　　　　// 统计
        System.out.println(watch.prettyPrint());
    }