package com.log.service;

import java.util.Enumeration;

import javax.servlet.ServletContext;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

import com.util.UtilPrint;

/**

 * 对应慕课网 3-1，http://www.imooc.com/video/5658，

 *  ServletContextListener的主要用途：

 * 1 定时器

 * 2 获取全局属性对象(设置全局属性对象)

 * 3 获取web.xml中的初始化参数

 * @author Wei

 * @time 2016年10月4日 下午8:38:37

 */

public class WylContextListener implements ServletContextListener {

	public WylContextListener() {

		System.out.println("com.log.service.WylContextListener()实例化,");

	}

	@Override

	public void contextInitialized(ServletContextEvent sce) {

		System.out.println("com.log.service.WylContextListener.contextInitialized()...,");

		ServletContext sc = sce.getServletContext();

		/**

		 * 设置全局变量，然后再整个应用的生命周期里都可以获取到

		 */

		sc.setAttribute("theGlobalPara", "我是全局的属性对象，");

		Enumeration<String> initparaNames = sc.getInitParameterNames();

		if (initparaNames.hasMoreElements()) {

			String name = initparaNames.nextElement();

			/**

			 * 获取web.xml中的初始化参数，

			 * <context-param>

			 * 		<param-name>ctxName</param-name>

			 * 		<param-value>我是ctx的值</param-value>

			 * </context-param>

			 */

			String initValue = sc.getInitParameter(name);

			UtilPrint.printWithSeparatorAndClass("------name:" + name + ",initValue:" + initValue,

					WylContextListener.class);

		} else {

			UtilPrint.printWithSeparatorAndClass("com.log.service.WylContextListener.contextInitialized()...,没有获取到初始化参数", WylContextListener.class);

		}

	}

	@Override

	public void contextDestroyed(ServletContextEvent sce) {

		// TODO Auto-generated method stub

		System.out.println("com.log.service.WylContextListener.contextDestroyed()...,");

	}

}

 <?xml version="1.0" encoding="UTF-8"?>

 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

     xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"

     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"

     id="WebApp_ID" version="2.5">

     <!-- 配置 Struts2 的 Filter -->

     <welcome-file-list>

         <!-- <welcome-file>index.jsp</welcome-file> 欢迎页改为MyTag.jsp -->

         <welcome-file>MyTag.jsp</welcome-file>

     </welcome-file-list>

     <listener>

         <listener-class>com.log.service.WylSessionAttrbuteLister</listener-class>

     </listener>

     <listener>

         <listener-class>com.log.service.WylSessionListener</listener-class>

     </listener>

     <!-- ServletRequestListener -->

     <listener>

         <listener-class>com.log.service.WylServletRequestListener</listener-class>

     </listener>

     <listener>

         <listener-class>com.log.service.WylContextListener</listener-class>

     </listener>

     <servlet>

         <servlet-name>freemarker</servlet-name>

         <servlet-class>freemarker.ext.servlet.FreemarkerServlet</servlet-class>

         <!--下面的配置freemarke的ftl文件的位置 -->

         <init-param>

             <param-name>TemplatePath</param-name>

             <param-value>/</param-value>

         </init-param>

         <!-- 是否和服务器（tommcat)一起启动。0为不。1为是 -->

         <load-on-startup>1</load-on-startup>

     </servlet>

     <servlet-mapping>

         <servlet-name>freemarker</servlet-name>

         <url-pattern>*.ftl</url-pattern>

     </servlet-mapping>

     <servlet>

         <!-- define a JspSupportServlet Object -->

         <servlet-name>JspSupportServlet</servlet-name>

         <servlet-class>org.apache.struts2.views.JspSupportServlet</servlet-class>

         <!-- setting JspSupportServlet auto start -->

         <load-on-startup>1</load-on-startup>

     </servlet>

     <!-- <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>

         </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern>

         </filter-mapping> -->

     <filter>

         <filter-name>struts2</filter-name>

         <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>struts2</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

     <!-- 我的自定义过滤器 -->

     <filter>

         <filter-name>wylFiler3</filter-name>

         <filter-class>com.test.javaAPI.servlet.MyFilter3</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>wylFiler3</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

     <filter>

         <filter-name>wylFiler4</filter-name>

         <filter-class>com.test.javaAPI.servlet.MyFilterXX</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>wylFiler4</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

     <filter>

         <filter-name>wylFiler1</filter-name>

         <filter-class>com.test.javaAPI.servlet.MyFilter1</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>wylFiler1</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

     <filter>

         <filter-name>wylFiler2</filter-name>

         <filter-class>com.test.javaAPI.servlet.MyFilter2</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>wylFiler2</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

     <!-- 测试servlet用的，20161004 -->

     <servlet>

         <servlet-name>testMy</servlet-name>

         <servlet-class>com.test.javaAPI.servlet.MyServlet</servlet-class>

     </servlet>

     <servlet-mapping>

         <servlet-name>testMy</servlet-name>

         <url-pattern>*.xxx</url-pattern>

     </servlet-mapping>

     <!-- 测试servlet用的，20161004 -->

     <servlet>

         <servlet-name>testMy2</servlet-name>

         <servlet-class>com.test.javaAPI.servlet.MyServlet2</servlet-class>

         <!-- 设置 web容器已启动就实例化这个servlet，servlet一旦实例化就会调用初始化方法init(),而且生命周期里只会实例化一次 -->

         <load-on-startup>1</load-on-startup>

     </servlet>

     <servlet-mapping>

         <servlet-name>testMy2</servlet-name>

         <url-pattern>*.yyy</url-pattern>

     </servlet-mapping>

     <!-- 可以通过通过监听器来获取到，当然了，需要实现ServletContextListener接口 ，

     见：com.log.service.WylContextListener-->

     <context-param>

         <param-name>ctxName</param-name>

         <param-value>我是ctx的值</param-value>

     </context-param>

 </web-app>