获取spring容器applicationContext的几种方式

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一、定义web.xml，由web容器自动加载配置文件初始化ApplicationContext实例，用WebApplicationContextUtils.getWebApplicationContext()得到ApplicationContext的引用。

方法1(web.xml)?
<web-app>?
?? <context-param>?
????? <param-name>contextConfigLocation</param-name>?
????? <param-value>/WEB-INF/applicationContext.xml</param-value>?
?? </context-param>?
<listener>?
??? <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>?
</listener>?
</web-app>?
方法2 (web.xml)?
<web-app>?
?? <context-param>?
????? <param-name>contextConfigLocation</param-name>?
????? <param-value>/WEB-INF/applicationContext.xml</param-value>?
?? </context-param>?
?? <servlet>?
????? <servlet-name>SpringContextServlet</servlet-name>?
????? <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>?
????? <load-on-startup>1</load-on-startup>?
?? </servlet>?
</web-app>?
方法3 在(struts-config.xml)中加载?
<plug-in className="org.springframework.web.struts.ContextLoaderPlugIn">?
??????? <set-property property="contextConfigLocation"?
??????????? value="/WEB-INF/applicationContext.xml,?
?????????????????? /WEB-INF/action-servlet.xml"/>?
</plug-in>

注：对于方法1，2如果xml配置文件比较多，可进行拆分，然后在applicationContext.xml配置文件加载被拆分的配置文件，通过<import resource=""/>加载被拆分的配置文件，如下：

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<?xml version="1.0" encoding="UTF-8"?>
<beans
?xmlns="http://www.springframework.org/schema/beans"
?xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
?xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.0.xsd">
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?<!-- 加载被拆分的Spring配置文件 -->
??? <import resource="applicationContext-dao.xml"/>???
??? <import resource="applicationContext-service.xml"/>

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</beans>

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通过web.xml配置，web容器会自动加载context-param中的配置文件初始化ApplicationContext实例，然后就可以在web应用中通过WebApplicationContextUtils.getWebApplicationContext方法获取ApplicationContext的引用

如:

????ApplicationContext ctx=WebApplicationContextUtils.getWebApplicationContext(request.getSession().getServletContext());?
??? LoginAction action=(LoginAction)ctx.getBean("action");

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编写SpringUtil.java,在构造方法中如下：

二、利用ClassPathXmlApplicationContext加载配置文件实例化applicationContext

???? 如下：

???????? ApplicationContext ac = new ClassPathXmlApplicationContext("/WEB-??? INF/applicationContext.xml");?

???? 或者

????????String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};???

?????? ApplicationContext ac = new ClassPathXmlApplicationContext(locations);
???? A a = (A)ac.getBean("a");

三、利用FileSystemXmlApplicationContext加载配置文件实例化applicationContext

????ApplicationContext ctx = new FileSystemXmlApplicationContext("/WEB-INF/applicationContext.xml");

??? 或者

??? String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};????????????

????ApplicationContext ctx = new FileSystemXmlApplicationContext(locations );

??? A a =(A)ctx.getBean("a");