1.默认都是类构造器实例化
<bean id=" XX" class=""/>
2.静态工厂方法。工厂类的方法是static的，直接在bean中配置class为工厂类，factory-method为指定static方法。
<bean id="ps" class="com.tazi.service.PersonServiceFactory" factory-method="createPersonServiceBean"/>
public class PersonServiceFactory{
public static PersonServiceBean createPersonServiceBean(){
return new PersonServiceBean();
}
}
3.实例化工厂方法。工厂类方法不是static,使用时先要配置工厂类，然后在bean中配置factory-bean和factory-method.
<bean id="psf" class="com.tazi.service.PersonServiceFactory" />
<bean id="ps" factory-bean="psf" factory-method="createPersonServiceBean"/>
public class PersonServiceFactory{
public PersonServiceBean createPersonServiceBean(){
return new PersonServiceBean();
}
}