spring ApplicationContext的实现

spring为ApplicationContext提供的3种实现分别 为：ClassPathXmlApplicationContext，FileSystemXmlApplicationContext和 XmlWebApplicationContext，其中XmlWebApplicationContext是专为Web工程定制的。使用举例如下：
    1. FileSystemXmlApplicationContext
        eg1. ApplicationContext ctx = new FileSystemXmlApplicationContext("bean.xml"); //加载单个配置文件
        eg2.
                String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};
                ApplicationContext ctx = new FileSystemXmlApplicationContext(locations ); //加载单个配置文件
        eg3.     
     ApplicationContext ctx =new FileSystemXmlApplicationContext("D:/project/bean.xml");//根据具体路径加载文件
   2. ClassPathXmlApplicationContext
        eg1.   ApplicationContext ctx = new ClassPathXmlApplicationContext("bean.xml");
        eg2.
                String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};
                ApplicationContext ctx = new ClassPathXmlApplication(locations);
        注：其中FileSystemXmlApplicationContext和ClassPathXmlApplicationContext与BeanFactory的xml文件定位方式一样是基于路径的。

       /**

       String path = "classpath:applicationContext*.xml";
       applicationContext = new ClassPathXmlApplicationContext(path);

       **/
3. XmlWebApplicationContext
    eg1. ServletContext servletContext = request.getSession().getServletContext();    
         ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(servletContext);

 

 

 三种实例化bean的方式：
1.使用类构造器实例化
<bean id=“orderService" class="cn.itcast.OrderServiceBean"/>
2.使用静态工厂方法实例化
<bean id="personService" class="cn.itcast.service.OrderFactory" factory-method="createOrder"/>
public class OrderFactory {
 public static OrderServiceBean createOrder(){
  return new OrderServiceBean();
 }
}
3.使用实例工厂方法实例化:
<bean id="personServiceFactory" class="cn.itcast.service.OrderFactory"/>
<bean id="personService" factory-bean="personServiceFactory" factory-method="createOrder"/>
public class OrderFactory {
 public OrderServiceBean createOrder(){
  return new OrderServiceBean();
 }
}