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