Spring提供了两种方式用于初始化WebApplicationContext,ServletContext监听器(ContextLoaderListener)、自启动Servlet(ContextLoaderServlet)。一个是基于Servlet2.3版本中新引入的Listener接口实现,而另一个基于Servlet接口实现。其中只有Servlet2.3以上版本的Web容器才支持ServletContext监听器方式初始化WebApplicationContext。
一、监听器方式(org.springframework.web.context.ContextLoaderListener)
1.ContextLoaderListener通过ServletContext上下文参数contextConfigLocation获取Spring配置文件的位置,在web.xml文件中Spring配置文件的位置,如下
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext.xml,/WEB-INF/beanConfig.xml</param-value>
</context-param>
在这里可以指定多个文件,多个文件之间用逗号或空格分割,也可以指定带资源类型前缀的路径配置,如“calsspath:/applicationContext.xml”、“classpath*:applicationContext*.xml”,对于未带资源类型前缀的路径配置默认其路径相对于Web部署的根路径。
classpath与classpath*的区别:假设有多个jar包或类路径下有一个相同的包名如(com.test),classpath只会在第一个加载的com.test包下查找,而classpath*会在所有jar包和类路径下查找。
2.在web.xml文件中配置监听器ContextLoaderListener,如下
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
<listener>
二、自启动Servlet方式(org.springframework.web.context.ContextLoaderServlet)
1.ContextLoaderServlet同样通过ServletContext上下文参数contextConfigLocation获取Spring配置文件的位置,配置跟ContextLoaderListener一样。
2.配置自启动ContextLoaderServlet,如下
<servlet>
<servlet-name>springContextLoaderServlet</servlet-name>
<servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
配置完成之后,即可通过
WebApplicationContextUtils.getWebApplicationContext方法在Web应用中获取ApplicationContext引用。
ex:ApplicationContext ctx=WebApplicationContextUtils.getWebApplicationContext();
LoginAction action=(LoginAction)ctx.getBean("action");
三、通过实现ApplicationContextAware 接口获得ApplicationContext
over write public void setApplicationContext(ApplicationContext context) throws BeansException
方法,获得ApplicationContext对象。
public class ApplicationContextRegister implements ApplicationContextAware {
private Log log = LogFactory.getLog(getClass());
public void setApplicationContext(ApplicationContext applicationContext)
throws BeansException {
ContextUtils.setApplicationContext(applicationContext);
log.debug("ApplicationContext registed");
}
}
public class ContextUtils {
private static ApplicationContext applicationContext;
private static Log log = LogFactory.getLog(ContextUtils.class);
public static void setApplicationContext(ApplicationContext applicationContext) {
synchronized (ContextUtils.class) {
log.debug("setApplicationContext, notifyAll");
ContextUtils.applicationContext = applicationContext;
ContextUtils.class.notifyAll();
}
}
public static ApplicationContext getApplicationContext() {
synchronized (ContextUtils.class) {
while (applicationContext == null) {
try {
log.debug("getApplicationContext, wait...");
ContextUtils.class.wait(60000);
if (applicationContext == null) {
log.warn("Have been waiting for ApplicationContext to be set for 1 minute", new Exception());
}
} catch (InterruptedException ex) {
log.debug("getApplicationContext, wait interrupted");
}
}
return applicationContext;
}
}
public static Object getBean(String name) {
return getApplicationContext().getBean(name);
}
}
配置文件:<bean class="com.sinotrans.framework.core.support.ApplicationContextRegister" />
四、some other normal way
public class AppManager extends ContextLoaderListener implements ServletContextListener {
private ServletContext context;
private WebApplicationContext webApplicationContext;
public void contextInitialized(ServletContextEvent sce) {
this.context = sce.getServletContext();
this.webApplicationContext = WebApplicationContextUtils.getRequiredWebApplicationContext(context);
this.context.setAttribute("WEBAPPLICATIONCONTEXT", webApplicationContext); }
}
use:
HttpSession session = request.getSession();
WebApplicationContext webApplicationContext = (WebApplicationContext)session.getServletContext().getAttribute("WEBAPPLICATIONCONTEXT");
UnsubscribeEmailFacade unsubscribeEmailFacade = (UnsubscribeEmailFacade)webApplicationContext.getBean(”“);
remark:
spring为ApplicationContext提供有三种实现分别为:ClassPathXmlApplicationContext,FileSystemXmlApplicationContext和XmlWebApplicationContext,其中XmlWebApplicationContext是专为Web工程定制的。
Spring WebApplicationContext的初始化方式&通过ApplicationContextAware获取bean
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转载自isabella-84.iteye.com/blog/2098165
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