| - Servlet监听器用于监听一些重要事件的发生，监听器对象可以在事情发生前、发生后可以做一些必要的处理 |
| - 通过实现Servlet API提供的Listense接口，可以在监听正在执行的某一个程序，并且根据程序的需求做出适当的响应 |
| - 监听作用域对象的创建和销毁以及属性的相关配置，可以添加一些公共的属性配置，做逻辑判断 |
- 也可以通过Log4j来做日志的记录等等 |
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|
| ## ServletRequest监听对象 |
|
| - 需要是实现的接口与重写方法 |
- servletRequestListener：监听request对象的创建和销毁 |
- public void requestDestroyed(ServletRequestEvent servletRequestEvent) request对象被销毁的时候添加的逻辑代码 |
- public void requestInitialized(ServletRequestEvent servletRequestEvent) request对象被初始化的时候添加的逻辑代码 |
- ServletRequestAttributeListener：监听request作用域属性的添加，删除和修改 |
- public void attributeAdded(ServletRequestAttributeEvent servletRequestAttributeEvent) :request作用域属性被添加的时候的逻辑代码 |
- public void attributeRemoved(ServletRequestAttributeEvent servletRequestAttributeEvent) :request作用域属性被删除的时候的逻辑代码 |
- public void attributeReplaced(ServletRequestAttributeEvent servletRequestAttributeEvent) :request作用域属性被修改的时候的逻辑代码 |
|
| ```java |
| package com.shanlei.listense; |
|
| import javax.servlet.*; |
| import java.util.Date; |
|
| /** |
| * @author: shanlei |
| * @version: 1.0 |
| */ |
| public class Mylistense implements ServletRequestListener, ServletRequestAttributeListener { |
| @Override |
| public void requestDestroyed(ServletRequestEvent servletRequestEvent) { |
| System.out.println("request对象被销毁--:"+new Date()); |
| } |
|
| @Override |
| public void requestInitialized(ServletRequestEvent servletRequestEvent) { |
| System.out.println("request对象被初始化---:"+new Date()); |
| } |
|
| @Override |
| public void attributeAdded(ServletRequestAttributeEvent servletRequestAttributeEvent) { |
| System.out.println("request对象属性被添加---："+new Date()); |
| System.out.println(servletRequestAttributeEvent.getName()); |
| System.out.println(servletRequestAttributeEvent.getValue()); |
| } |
|
| @Override |
| public void attributeRemoved(ServletRequestAttributeEvent servletRequestAttributeEvent) { |
| System.out.println("request对象属性被删除---："+new Date()); |
| } |
|
| @Override |
| public void attributeReplaced(ServletRequestAttributeEvent servletRequestAttributeEvent) { |
| System.out.println("request对象属性被修改---："+new Date()); |
| } |
| } |
| ``` |
|
|
|
| ## ServletContext监听对象 |
|
| - 需要是实现的接口与重写方法 |
- ServletContextListener：监听servletContext对象的创建和销毁 |
- public void contextDestroyed(ServletContextEvent servletContextEvent) servletContext对象被销毁的时候添加的逻辑代码 |
- public void contextInitialized(ServletContextEvent servletContextEvent) servletContext对象被初始化的时候添加的逻辑代码 |
- ServletContextAttributeListener：监听servletContext作用域属性的添加，删除和修改 |
- public void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent) :servletContext作用域属性被添加的时候的逻辑代码 |
- public void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent) :servletContext作用域属性被删除的时候的逻辑代码 |
- public void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent) :servletContext作用域属性被修改的时候的逻辑代码 |
|
| ```java |
| package com.shanlei.listense; |
|
| import javax.servlet.*; |
| import java.util.Date; |
|
| /** |
| * @author: shanlei |
| * @version: 1.0 |
| */ |
| public class Mylistense implements ServletContextListener, ServletContextAttributeListener { |
| @Override |
| public void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent) { |
| System.out.println("ervletContext对象属性被添加---："+new Date()); |
| System.out.println(servletContextAttributeEvent.getName()); |
| System.out.println(servletContextAttributeEvent.getValue()); |
| } |
|
| @Override |
| public void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent) { |
| System.out.println("servletContext对象属性被删除---："+new Date()); |
| System.out.println(servletContextAttributeEvent.getName()); |
| System.out.println(servletContextAttributeEvent.getValue()); |
| } |
|
| @Override |
| public void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent) { |
| System.out.println("servletContext对象属性被修改---："+new Date()); |
| System.out.println(servletContextAttributeEvent.getName()); |
| System.out.println(servletContextAttributeEvent.getValue()); |
| } |
|
| @Override |
| public void contextInitialized(ServletContextEvent servletContextEvent) { |
| System.out.println("servletContext对象被初始化--:"+new Date()); |
| } |
|
| @Override |
| public void contextDestroyed(ServletContextEvent servletContextEvent) { |
| System.out.println("servletContext对象被销毁--:"+new Date()); |
| } |
| } |
| ``` |
|
| ## HttpSession监听对象 |
|
| - 需要是实现的接口与重写方法 |
- HttpSessionListener：监听session的创建与销毁 |
- public void sessionCreated(HttpSessionEvent httpSessionEvent) session对象被创建的时候添加的逻辑代码 |
- public void sessionDestroyed(HttpSessionEvent httpSessionEvent) session对象被销毁的时候添加的逻辑代码 |
- HttpSessionAttributeListener：监听session的属性的添加、删除与修改 |
- public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) :session添加属性的时候添加的逻辑代码 |
- public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) :session添加属性的时候删除的逻辑代码 |
- public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) :session添加属性的时候修改的逻辑代码 |
- HttpSessionActivationListenser是在session被持久化后当被重新读取到内存中的时候使用的监听器，一般不使用 |
- HttpSessionBindingListener绑定监听器，需要另外创建对象才能实现监听，所以也一般不使用 |
|
| ```java |
| package com.shanlei.listense; |
|
| import javax.servlet.http.HttpSessionAttributeListener; |
| import javax.servlet.http.HttpSessionBindingEvent; |
| import javax.servlet.http.HttpSessionEvent; |
| import javax.servlet.http.HttpSessionListener; |
|
| /** |
| * @author: shanlei |
| * @version: 1.0 |
| */ |
| public class SessionListense implements HttpSessionListener, HttpSessionAttributeListener { |
| @Override |
| public void sessionCreated(HttpSessionEvent httpSessionEvent) { |
| System.out.println("session对象被创建"); |
| } |
|
| @Override |
| public void sessionDestroyed(HttpSessionEvent httpSessionEvent) { |
| System.out.println("session对象被销毁"); |
| } |
|
| @Override |
| public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) { |
| System.out.println("session添加属性"); |
| System.out.println(httpSessionBindingEvent.getName()); |
| System.out.println(httpSessionBindingEvent.getValue()); |
| } |
|
| @Override |
| public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) { |
| System.out.println("session删除属性"); |
| System.out.println(httpSessionBindingEvent.getName()); |
| System.out.println(httpSessionBindingEvent.getValue()); |
| } |
|
| @Override |
| public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) { |
| System.out.println("session修改属性"); |
| System.out.println(httpSessionBindingEvent.getName()); |
| System.out.println(httpSessionBindingEvent.getValue()); |
| } |
| } |
|
| ``` |
