非常好用的性能监控类StopWatch
注明来自：http://stackoverflow.com/questions/1238678/stopwatch-class-for-java
The Spring Framework has an excellent StopWatch class:

StopWatch stopWatch = new StopWatch("My Stop Watch");

stopWatch.start("initializing");
Thread.sleep(2000); // simulated work
stopWatch.stop();

stopWatch.start("processing");
Thread.sleep(5000); // simulated work
stopWatch.stop();

stopWatch.start("finalizing");
Thread.sleep(3000); // simulated work
stopWatch.stop();

System.out.println(stopWatch.prettyPrint());

This produces:

StopWatch 'My Stop Watch': running time (millis) = 10000
-----------------------------------------
ms % Task name
-----------------------------------------
02000 020% initializing
05000 050% processing
03000 030% finalizing