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