1 package tw.com.javaworld.CH10;
2 
3 import java.util.*;
4 import javax.servlet.http.*;
5 import tw.com.javaworld.CH10.UserList;
6 
7 public class UserTrace implements javax.servlet.http.HttpSessionBindingListener {
8     
9     private String user_name;
10    private UserList container = UserList.getInstance();
11    
12    public String getUserName() {
13        return user_name;
14    }
15    
16    public void setUserName(String name) {
17        user_name = name;
18    }
19
20    // 當UserTrace被加入session物件時會呼叫此方法   
21    public void valueBound(HttpSessionBindingEvent event) {
22    }
23
24    // 當UserTrace被移出session物件時會呼叫此方法   
25    public void valueUnbound(HttpSessionBindingEvent event) {
26        container.removeUser(user_name);
27    }
28}
29