分段计时器StopWatch使用

StopWatch需要依赖spring-core这个jar包
主要作用
记录开始时间点
记录结束时间点
输出执行时间及各个时间段的占比

	public static void main(String[] args) {
		StopWatch sw = new StopWatch("test");
		sw.start("task1");
		// do something
		try {
			Thread.sleep(100);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		sw.stop();
		sw.start("task2");
		// do something
		try {
			Thread.sleep(200);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		sw.stop();
		System.out.println("~~~~~~~~~~~~~~~~~");
		System.out.println(sw.prettyPrint());
	}