Spring学习（一） 三种实例化bean的方式
1.使用类构造器实例化

<bean id="personService" name="code"><bean id="personService2"           factory-method="createPersonServiceBean"/>

public static PersonServiceBean createPersonServiceBean(){return new PersonServiceBean();//通过工厂类的静态方法创建PersonServiceBean对象}

3.使用实例化工厂方法实例化
先实例化工厂类PersonServiceBeanFactory，然后再通过工厂类的方法创建PersonServiceBean对象

<bean id="personServiceFactory" factory-bean="personServiceFactory" factory-method="createPersonServiceBean2"/>

public PersonServiceBean createPersonServiceBean2(){return new PersonServiceBean();}