监听器学习2

骑猪看日落 2023-10-17 18:36 63阅读 0赞

1、ServletRequestAttributeListener监听request对象属性的添加，删除，修改

2、HttpSessionAttributeListener监听session对象属性的添加，删除，修改

HttpSession session = se.getSession();  
Object old = se.getValue();  
Object new\_o = session.getAttribute("a");  
System.out.println("修改的属性旧的值是"+old);  
System.out.println("修改的属性新的值是"+new\_o);

/\*\*如果是字符串的时候  
\* 添加的属性是11111111111  
修改的属性旧的值是11111111111  
修改的属性新的值是2222222222222  
移除的属性是2222222222222  
\*/  
/\*\*如果是对象的时候  
\* -----------------------绑定--------------------  
添加的属性是[objectBiding.Admin@2766b7e6][objectBiding.Admin_2766b7e6]  
\-----------------------绑定--------------------  
\-----------------------移除--------------------  
修改的属性旧的值是[objectBiding.Admin@48b3713f][objectBiding.Admin_48b3713f]  
修改的属性新的值是[objectBiding.Admin@48b3713f][objectBiding.Admin_48b3713f]  
\-----------------------移除--------------------  
移除的属性是[objectBiding.Admin@48b3713f][objectBiding.Admin_48b3713f]  
\*/

3、ServletContextAttributeListener监听servletcontext对象属性的添加，删除，修改

1、HttpSessionBidingListener 对象绑定到session的时候监听

package objectBiding;

import javax.servlet.http.HttpSessionBindingEvent;  
import javax.servlet.http.HttpSessionBindingListener;

public class Admin implements HttpSessionBindingListener \{

private String name;  
private String password;  
  
public Admin() \{  
super();  
\}

public Admin(String name, String password) \{  
super();  
this.name = name;  
this.password = password;  
\}

public String getName() \{  
return name;  
\}

public void setName(String name) \{  
this.name = name;  
\}

public String getPassword() \{  
return password;  
\}

public void setPassword(String password) \{  
this.password = password;  
\}

@Override  
public void valueBound(HttpSessionBindingEvent event) \{  
// TODO Auto-generated method stub  
System.out.println("-----------------------绑定--------------------");  
\}

@Override  
public void valueUnbound(HttpSessionBindingEvent event) \{  
// TODO Auto-generated method stub

System.out.println("-----------------------移除--------------------");  
\}

[objectBiding.Admin_2766b7e6]: mailto:objectBiding.Admin@2766b7e6
[objectBiding.Admin_48b3713f]: mailto:objectBiding.Admin@48b3713f