ServletContextListener

在Servlet API中有一个ServletContextListener接口，它能够监听ServletContext对象的生命周期，实际上就是监听Web应用的生命周期。

当Servlet容器启动或终止Web应用时，会触发ServletContextEvent事件，该事件由 ServletContextListener 来处理。在 ServletContextListener 接口中定义了处理ServletContextEvent事件的两个方法。

contextInitialized(ServletContextEvent sce)：当Servlet容器启动Web应用时调用该方法。在调用完该方法之后，容器再对Filter初始化，并且对那些在Web应用启动时就需要被初始化的Servlet进行初始化。

contextDestroyed(ServletContextEvent sce)：当Servlet容器终止Web应用时调用该方法。在调用该方法之前，容器会先销毁所有的Servlet和Filter过滤器。

public class QuartzInitializerListener implements ServletContextListener {}

public class ContextLoaderListener extends ContextLoader implements ServletContextListener {}

下面在Quartz上通过ServletContextListener得到ServletContext，从而能在任务中得到ServletContext：

public class QuartzServletContextListener extends QuartzInitializerListener {public static final String MY_CONTEXT_NAME = "servletContext";@Overridepublic void contextDestroyed(ServletContextEvent sce) {// TODO Auto-generated method stubsuper.contextDestroyed(sce);}@Overridepublic void contextInitialized(ServletContextEvent sce) {// TODO Auto-generated method stubsuper.contextInitialized(sce);ServletContext servletContext = sce.getServletContext();StdSchedulerFactory factory = (StdSchedulerFactory) servletContext.getAttribute(QuartzInitializerListener.QUARTZ_FACTORY_KEY);try {factory.getScheduler().getContext().put(QuartzServletContextListener.MY_CONTEXT_NAME, servletContext);} catch (SchedulerException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

Job中得到ServletContext：

public class XLSJob  implements StatefulJob {public void execute(JobExecutionContext arg0) throws JobExecutionException {// TODO Auto-generated method stubtry {ServletContext context = null;try {context = (ServletContext) arg0.getScheduler().getContext().get(QuartzServletContextListener.MY_CONTEXT_NAME);} catch (SchedulerException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}WebApplicationContext conn=(WebApplicationContext)context.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);  }}

因为要监听ServletContext，最后在web.xml配置该监听：

<listener><listener-class>x.x.x.QuartzServletContextListener</listener-class></listener>