java根据sessionId创建、删除session

在有些情况下可能需要根据sessionId来增删改session，这时候我们可以通过监听来实现。代码如下。

1、创建监听MySessionListener.java

public class MySessionListener {    public void sessionCreated(HttpSessionEvent httpSessionEvent) {        MySessionContext.AddSession(httpSessionEvent.getSession());    }    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {        HttpSession session = httpSessionEvent.getSession();        MySessionContext.DelSession(session);    }}

2、创建MySessionContext.java

public class MySessionContext {    private static HashMap mymap = new HashMap();        public static synchronized void AddSession(HttpSession session) {                if (session != null) {                        mymap.put(session.getId(), session);                     }             }         public static synchronized void DelSession(HttpSession session) {                 if (session != null) {                         mymap.remove(session.getId());                     }             }         public static synchronized HttpSession getSession(String session_id) {                if (session_id == null)                     return null;                 return (HttpSession) mymap.get(session_id);             }}

3、在web.xml中加入

<listener>    <listener-class>路径.MySessionListener</listener-class></listener>

这样就可以了

HttpSession session = MySessionContext.getSession(sessionId);