ApplicationContext是Spring的容器环境，通过ApplicationContext对象可以访问所有配置的bean。
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：
一、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
[url]http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd[/url]"
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 >
< 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
[url]http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd[/url]"
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>
二、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
[url]http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd[/url]"
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
[url]http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd[/url]"
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。
下面给出本例子的工程源码。
本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/126570，如需转载请自行联系原作者
