参考地址：
http://blog.csdn.net/fenglibing/article/details/7083071
oracle地址：
http://docs.oracle.com/javase/1.4.2/docs/guide/jar/jar.html#Service Provider
http://docs.oracle.com/javase/6/docs/api/java/util/ServiceLoader.html
例子：
http://blog.csdn.net/fenglibing/article/details/7083526
