Listener、Filter----总结

本文深入探讨了Java Web中的监听器与过滤器机制,包括ServletContextListener的应用部署初始化,HttpSessionListener的在线人数统计,HttpSessionActivationListener的钝化活化处理,以及Filter的使用频率与生命周期管理。

Listener

8个

三种类型

针对三个作用域的创建和销毁
针对三个作用域的值改变 【添加 | 替换 | 移除】
针对session中的值 【钝化 活化】 , 【绑定 解绑】

钝化 ( 序列化 )

内存中的对象存储到硬盘

超时失效。 session销毁了。

非正常关闭服务器, 钝化 。 正常关闭服务器 销毁

设置了session,多久时间。 context.xml

活化 (反序列化)

从硬盘里面读取到内存

ServletContextListner : 应用被部署的时候, 服务器加载这个项目的时候,做一些初始化工作, 任务调度。
HttpSessionListener : 统计在线人数
HttpSessionActivationListener : 钝化活化处理

Filter

使用频率更高

  • 如果要写一个过滤器。
  1. 定义一个类,实现接口 Filter
  1. 注册 . web.xml . 与servlet相似。
  • 过滤器放行。

chain.doFilter(request, response);

  • 过滤器生命周期

    创建: 服务器加载这个项目的时候创建实例

    销毁: 关闭服务器或者从服务器中移除项目的时候。

<?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_3_0.xsd" version="3.0"> <display-name></display-name> <context-param> <param-name>contextConfigLocation</param-name> <param-value> classpath*:applicationContext*.xml classpath*:*Context.xml </param-value> </context-param> <context-param> <param-name>webAppRootKey</param-name> <param-value>rms.root</param-value> </context-param> <context-param> <param-name>log4jConfigLocation</param-name> <param-value>/WEB-INF/classes/log4j.properties</param-value> </context-param> <context-param> <param-name>log4jRefreshInterval</param-name> <param-value>60</param-value> </context-param> <listener> <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> </listener> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <listener> <listener-class>com.hg.filter.UrlAuthListen</listener-class> </listener> <listener> <listener-class>com.hg.filter.WebConfigListener</listener-class> </listener> <filter> <filter-name>openSessionInViewFilter</filter-name> <filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter </filter-class> <init-param> <param-name>singleSession</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>openSessionInViewFilter</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> <filter> <filter-name>XssFilter</filter-name> <filter-class>com.hg.aop.XssFilter</filter-class> </filter> <filter-mapping> <filter-name>XssFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- dwr 配置 --> <servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> <init-param> <param-name>activeReverseAjaxEnabled</param-name> <param-value>true</param-value> </init-param> <init-param> <param-name>crossDomainSessionSecurity</param-name> <param-value>false</param-value> </init-param> <init-param> <description>How quickly do scriptSessions timeout?</description> <param-name>scriptSessionTimeout</param-name> <param-value>1800000</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping> <listener> <listener-class>org.directwebremoting.servlet.EfficientShutdownServletContextAttributeListener</listener-class> </listener> <!-- dwr 配置 --> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>具体解释一下web.xml的配置
07-08
<?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"> <display-name>agileEx</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-*.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <filter> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>agileEx</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/springMvc.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>agileEx</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <filter> <display-name>PpmFilter</display-name> <filter-name>PpmFilter</filter-name> <filter-class>com.dahuatech.core.interceptor.PpmFilter</filter-class> </filter> <filter-mapping> <filter-name>PpmFilter</filter-name> <url-pattern>/property/*</url-pattern> </filter-mapping> <filter> <display-name>TpmFilter</display-name> <filter-name>TpmFilter</filter-name> <filter-class>com.dahuatech.core.interceptor.TpmFilter</filter-class> </filter> <filter-mapping> <filter-name>TpmFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>dimission</display-name> <filter-name>dimission</filter-name> <filter-class>com.dahuatech.core.interceptor.DimissionFilter</filter-class> </filter> <filter-mapping> <filter-name>dimission</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>RestAuthFilter</display-name> <filter-name>RestAuthFilter</filter-name> <filter-class>com.dahuatech.core.interceptor.RestAuthFilter</filter-class> </filter> <filter-mapping> <filter-name>RestAuthFilter</filter-name> <url-pattern>/rest/*</url-pattern> </filter-mapping> </web-app>
11-15
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