Java根据sessionId获取Session对象

1. 建立一个自己的SessionContext：

package cn.org.jshuwei.session.core;  
  
import javax.servlet.http.HttpSession;  
import java.util.HashMap;  
  
public class MySessionContext {  
private static MySessionContext instance;  
private HashMap mymap;  
  
private MySessionContext() {  
mymap = new HashMap();  
}  
  
public static MySessionContext getInstance() {  
if (instance == null) {  
instance = new MySessionContext();  
}  
return instance;  
}  
  
public synchronized void AddSession(HttpSession session) {  
if (session != null) {  
mymap.put(session.getId(), session);  
}  
}  
  
public synchronized void DelSession(HttpSession session) {  
if (session != null) {  
mymap.remove(session.getId());  
}  
}  
  
public synchronized HttpSession getSession(String session_id) {  
if (session_id == null) return null;  
return (HttpSession) mymap.get(session_id);  
}  
  
}  

　　2.新建一个Session监听

package cn.org.jshuwei.session.core;

import javax.servlet.http.HttpSessionListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSession;
import java.util.HashMap;
import java.util.Map;

public class SessionListener implements HttpSessionListener {
public static Map userMap = new HashMap();
private   MySessionContext myc=MySessionContext.getInstance();

public void sessionCreated(HttpSessionEvent httpSessionEvent) {
myc.AddSession(httpSessionEvent.getSession());
}

public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
HttpSession session = httpSessionEvent.getSession();
myc.DelSession(session);
}
}

　　3.在web.xml中配置

<listener>  
<listener-class>cn.org.jshuwei.session.core.SessionListener</listener-class>  
</listener> 

　　4.使用

MySessionContext myc= MySessionContext.getInstance();  
HttpSession sess = myc.getSession(sessionId);  

　　

转载自--------------http://blog.csdn.net/hecongqi/article/details/6859034