在Web开发开发中，常常需要从JSP或者Servlet或者Action中获取ApplicationContext对象，这时候，就无法使用new关键字通过查找配置文件来实例化ApplicationContext这个对象了。Spring通过WebApplicationContextUtils可以方便实现您的需求。下面看个例子：
Spring2.5+Struts2环境下
1. 配置web.xml，通过这个配置来获取的。
＜?xml version="1.0" encoding="UTF-8"?＞ ＜web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"＞ ＜context-param＞ ＜param-name＞contextConfigLocation＜/param-name＞ ＜param-value＞/WEB-INF/applicationContext.xml＜/param-value＞ ＜/context-param＞ ＜filter＞ ＜filter-name＞struts2＜/filter-name＞ ＜filter-class＞org.apache.struts2.dispatcher.FilterDispatcher＜/filter-class＞ ＜/filter＞ ＜filter-mapping＞ ＜filter-name＞struts2＜/filter-name＞ ＜url-pattern＞/*＜/url-pattern＞ ＜/filter-mapping＞ ＜listener＞ ＜listener-class＞org.springframework.web.context.ContextLoaderListener＜/listener-class＞ ＜/listener＞ ＜servlet＞ ＜servlet-name＞dispatcher＜/servlet-name＞ ＜servlet-class＞org.springframework.web.servlet.DispatcherServlet＜/servlet-class＞ ＜load-on-startup＞1＜/load-on-startup＞ ＜/servlet＞ ＜servlet-mapping＞ ＜servlet-name＞dispatcher＜/servlet-name＞ ＜url-pattern＞*.form＜/url-pattern＞ ＜/servlet-mapping＞ ＜/web-app＞
2. 在JSP、Servlet、Action中获取ApplicationContext
＜%@ page import="lavasoft.service.TestService" %＞
＜%@ page import="org.springframework.context.ApplicationContext" %＞
＜%@ page import="org.springframework.web.context.support.WebApplicationContextUtils" %＞
＜%@ page contentType="text/html;charset=UTF-8" language="java" %＞
＜html＞
＜head＞＜title＞Simple jsp page＜/title＞＜/head＞
＜body＞
＜%
// ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(request.getSession().getServletContext());
ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(session.getServletContext());
TestService service = (TestService) ctx.getBean("testService");
String s = service.test();
out.print(s);
%＞
＜/body＞
＜/html＞
＜%@ page import="org.springframework.context.ApplicationContext" %＞
＜%@ page import="org.springframework.web.context.support.WebApplicationContextUtils" %＞
＜%@ page contentType="text/html;charset=UTF-8" language="java" %＞
＜html＞
＜head＞＜title＞Simple jsp page＜/title＞＜/head＞
＜body＞
＜%
// ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(request.getSession().getServletContext());
ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(session.getServletContext());
TestService service = (TestService) ctx.getBean("testService");
String s = service.test();
out.print(s);
%＞
＜/body＞
＜/html＞
Spring+JSP的环境
在此环境下web.xml配置会有些变化：
＜?xml version="1.0" encoding="UTF-8"?＞
＜web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5"＞
＜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＞
＜servlet＞
＜servlet-name＞dispatcher＜/servlet-name＞
＜servlet-class＞org.springframework.web.servlet.DispatcherServlet＜/servlet-class＞
＜load-on-startup＞1＜/load-on-startup＞
＜/servlet＞
＜servlet-mapping＞
＜servlet-name＞dispatcher＜/servlet-name＞
＜url-pattern＞*.form＜/url-pattern＞
＜/servlet-mapping＞
＜/web-app＞
＜web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5"＞
＜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＞
＜servlet＞
＜servlet-name＞dispatcher＜/servlet-name＞
＜servlet-class＞org.springframework.web.servlet.DispatcherServlet＜/servlet-class＞
＜load-on-startup＞1＜/load-on-startup＞
＜/servlet＞
＜servlet-mapping＞
＜servlet-name＞dispatcher＜/servlet-name＞
＜url-pattern＞*.form＜/url-pattern＞
＜/servlet-mapping＞
＜/web-app＞
获取的方式和上述完全一样。
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