javaweb监听器和juery技术

监听servlet创建

package com.hspedu.listener;import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;/*** 老韩解读* 1. 当一个类实现了 ServletContextListener* 2. 该类就是一个监听器* 3. 该类可以监听的事件 由该类实现的监听接口决定 ，比如 实现ServletContextListener*    , 则该类就可以监听 ServletContext对象的创建和销毁, 以此类推* 4. HspServletContextListener 就是一个监听者* 5. 当web应用启动时，就会产生 ServletContextEvent 事件, 会调用监听器的对应事件处理方法*    contextInitialized, 同时会传递 事件对象* 6. 程序员可以通过 ServletContextEvent 事件对象，来获取需要的信息, 然后再进行业务处理* 7. tomcat怎么知道这个监听器存在 ? 因为我们需要在web.xml中配置*/
public class HspServletContextListener implements ServletContextListener {@Overridepublic void contextInitialized(ServletContextEvent servletContextEvent) {ServletContext servletContext = servletContextEvent.getServletContext();System.out.println("HspServletContextListener 监听到 " +servletContext + " 被创建..");//如果我们获取到ServletContext 对象..进行业务处理}@Overridepublic void contextDestroyed(ServletContextEvent servletContextEvent) {ServletContext servletContext = servletContextEvent.getServletContext();System.out.println("HspServletContextListener 监听到 " +servletContext + " 被销毁..");//比如可以对servletContext 数据进行处理， 或者日志的管理...System.out.println("进行处理工作.....");}
}

HspHttpSessionListener 监听到 session销毁= FAEC215D4C92B5325848CF7438FC7138
用户id=FAEC215D4C92B5325848CF7438FC7138 离线
HspHttpSessionListener 监听到 session销毁= 2785B79C0D9A36C33CA215EA5C23D254
用户id=2785B79C0D9A36C33CA215EA5C23D254 离线

监听文本属性的变化

package com.hspedu.listener;import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;public class HspServletContextAttributeListener implements ServletContextAttributeListener {@Overridepublic void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent) {System.out.println("HspServletContextAttributeListener 监听到添加属性.."+ servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );}@Overridepublic void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent) {System.out.println("HspServletContextAttributeListener 监听到删除属性.."+ servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );}@Overridepublic void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent) {System.out.println("HspServletContextAttributeListener 监听到修改属性.."+ servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );}
}

package com.hspedu.servlet;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;public class HiServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//给servletContext 对象操作属性ServletContext servletContext = request.getServletContext();servletContext.setAttribute("name", "韩顺平教育");servletContext.setAttribute("name", "老韩教育");servletContext.removeAttribute("name");//获取session对象//FilterHttpSession session = request.getSession();session.setAttribute("age", 100);session.setAttribute("age", 400);session.removeAttribute("age");System.out.println("HiServlet 处理完毕....");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}
}

HspHttpSessionListener 监听到 session销毁= FAEC215D4C92B5325848CF7438FC7138
用户id=FAEC215D4C92B5325848CF7438FC7138 离线
HspHttpSessionListener 监听到 session销毁= 2785B79C0D9A36C33CA215EA5C23D254
用户id=2785B79C0D9A36C33CA215EA5C23D254 离线
HspRequestListener 监听到 request对象创建
记录访问日志....
访问IP= 127.0.0.1
访问的资源= http://localhost:8080/filter/hi
HspServletContextAttributeListener 监听到添加属性..name=韩顺平教育
HspServletContextAttributeListener 监听到修改属性..name=韩顺平教育
HspServletContextAttributeListener 监听到删除属性..name=老韩教育
HspHttpSessionListener 监听到 session创建= A8714B2384A7FF7505EA20A456952DAC
用户id=A8714B2384A7FF7505EA20A456952DAC 上线
HspHttpSessionAttributeListener 监听到session添加属性age=100
HspHttpSessionAttributeListener 监听到session修改属性age=100
HspHttpSessionAttributeListener 监听到session删除属性age
HiServlet 处理完毕....
HspRequestListener 监听到 request对象被销毁

监听session创建

package com.hspedu.listener;import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;public class HspHttpSessionListener implements HttpSessionListener {@Overridepublic void sessionCreated(HttpSessionEvent httpSessionEvent) {HttpSession session = httpSessionEvent.getSession();//当session创建时，我们给它设置一个生命周期 30ssession.setMaxInactiveInterval(30);System.out.println("HspHttpSessionListener 监听到 session创建= " +session.getId());System.out.println("用户id=" + session.getId() + " 上线");}@Overridepublic void sessionDestroyed(HttpSessionEvent httpSessionEvent) {HttpSession session = httpSessionEvent.getSession();System.out.println("HspHttpSessionListener 监听到 session销毁= " +session.getId());System.out.println("用户id=" + session.getId() + " 离线");}
}

监听session属性改变

package com.hspedu.listener;import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;public class HspHttpSessionAttributeListener implements HttpSessionAttributeListener {@Overridepublic void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {//HttpSession session = httpSessionBindingEvent.getSession();System.out.println("HspHttpSessionAttributeListener 监听到session添加属性" +httpSessionBindingEvent.getName() + "=" + httpSessionBindingEvent.getValue());}@Overridepublic void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {HttpSession session = httpSessionBindingEvent.getSession();System.out.println("HspHttpSessionAttributeListener 监听到session删除属性" +httpSessionBindingEvent.getName());}@Overridepublic void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {System.out.println("HspHttpSessionAttributeListener 监听到session修改属性" +httpSessionBindingEvent.getName() + "=" + httpSessionBindingEvent.getValue());}
}

监听request

package com.hspedu.listener;import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;public class HspRequestListener implements ServletRequestListener {@Overridepublic void requestInitialized(ServletRequestEvent servletRequestEvent) {System.out.println("HspRequestListener 监听到 request对象创建");ServletRequest servletRequest = servletRequestEvent.getServletRequest();System.out.println("记录访问日志....");System.out.println("访问IP= " + servletRequest.getRemoteAddr());System.out.println("访问的资源= " + ((HttpServletRequest)servletRequest).getRequestURL());}@Overridepublic void requestDestroyed(ServletRequestEvent servletRequestEvent) {System.out.println("HspRequestListener 监听到 request对象被销毁");}}