写代码过程中，我们经常需要记录接口调用的时间，以便进行调优。之前我的做法是利用java相应时间处理类计算出时间。这样下来代码写得十分臃肿，今天偶然得知apache common lang包中有一个十分方便的类可以完成该功能。下面贴出使用方法：

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private static void test01() throws InterruptedException {  
    StopWatch watch = new StopWatch();  
    watch.start();  
    Thread.sleep(1000);  
    watch.split();  
    /* 
     * This is the time between start and latest lit. 
     * 调用start()方法到最后一次调用split()耗用的时间 
     */  
     System.out.println(watch.getSplitTime());  
     Thread.sleep(2000);  
     watch.split();  
     System.out.println(watch.getSplitTime());  
     Thread.sleep(500);  
     watch.stop();  
     /* 
      * This is either the time between the start and the moment this method 
      * is called, or the amount of time between start and stop 
      * 调用start()方法到调用getTime()或stop()方法耗用的时间 
      */  
     System.out.println(watch.getTime());  
 }

start —记录起始时间
split —记录调用此方法的时间