Uploadify获取Session

前台通过uploadify上传文件，原本在action中获取session中的用户信息，但是发现为空，而通过sessionid获取session的方法HttpSessionContext.getSession(java.lang.String sessionId)又被废弃，所以通过实现HttpSessionListener的sessionCreated和sessionDestroyed来解决问题。步骤如下：
1、建立自己的SessionContext

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、新增一个Session监听类

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

	public void sessionCreated(HttpSessionEvent httpSessionEvent) {
		// TODO Auto-generated method stub
		myc.AddSession(httpSessionEvent.getSession()); 
	}

	public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
		// TODO Auto-generated method stub
		HttpSession session = httpSessionEvent.getSession();  
		myc.delSession(session);

	}

}

3、在Web.xml中配置监听

<listener>
		<listener-class>
			com.render.util.SessionListener
		</listener-class>
</listener>

4、在程序中使用

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

获取session