ContextListener的基本知识

最新推荐文章于 2023-11-10 22:25:05 发布

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最新推荐文章于 2023-11-10 22:25:05 发布

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分类专栏： Apache/Tomcat/集群文章标签： initialization tomcat class components object servlet

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本文介绍如何在Tomcat启动和关闭时执行特定任务，如覆盖率数据写入等。通过实现`ServletContextListener`接口并覆盖`contextInitialized`及`contextDestroyed`方法，在web.xml文件中配置监听器来实现。

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很多时候我们都需要在tomcat启动的时候做一些事情,或者在tomcat停止的时候也做一些事情.(比如覆盖率数据的写入.)

Object	Event	Listener Interface and Event Class
Web context (see Accessing the Web Context )	Initialization and destruction	`javax.servlet. ServletContextListener` and `ServletContextEvent`
Web context (see Accessing the Web Context )	Attribute added, removed, or replaced	`javax.servlet. ServletContextAttributeListener` and `ServletContextAttributeEvent`
Session (See Maintaining Client State )	Creation, invalidation, activation, passivation, and timeout	`javax.servlet.http. HttpSessionListener` , `javax.servlet.http. HttpSessionActivationListener` , and `HttpSessionEvent`
Session (See Maintaining Client State )	Attribute added, removed, or replaced	`javax.servlet.http. HttpSessionAttributeListener` and `HttpSessionBindingEvent`
Request	A servlet request has started being processed by web components	`javax.servlet. ServletRequestListener` and `ServletRequestEvent`
Request	Attribute added, removed, or replaced	`javax.servlet. ServletRequestAttributeListener` and `ServletRequestAttributeEvent`

//在web.xml中配置listener

//这样tomcat启动的时候会跑contextInitialized.

//tomcat停止的时候会跑contextDestroyed.

import javax.servlet.*;

import util.Counter;



public final class ContextListener

  implements ServletContextListener {

  private ServletContext context = null;

  public void contextInitialized(ServletContextEvent event) {

     context = event.getServletContext();

      ...

  }



  public void contextDestroyed(ServletContextEvent event) {

　　　// cobertura写入测试数据.

　　　try {

    　　　　String className = "net.sourceforge.cobertura.coveragedata.ProjectData";

    　　　　String methodName = "saveGlobalProjectData";

    　　　　Class saveClass = Class.forName(className);

    　　　　java.lang.reflect.Method saveMethod = saveClass.getDeclaredMethod(methodName, new Class[0]);

    　　　　saveMethod.invoke(null,new Object[0]);

　　　　} catch (Throwable t) {

　　　　}

  }