获得HttpServletRequest 和HttpSession对象

package org.jeecgframework.core.util;  
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;  
/**
* @ClassName: ContextHolderUtils
* @Description: TODO(上下文工具类)
* @author  张代浩
* @date 2012-12-15 下午11:27:39
*
 */
public class ContextHolderUtils {
    /**
     * SpringMvc下获取request
     *
     * @return
     */
    public static HttpServletRequest getRequest() {
        HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
        return request;  
    }  
    /**
     * SpringMvc下获取session
     *
     * @return
     */
    public static HttpSession getSession() {
        HttpServletRequest request = getRequest();
        String tempSessionId = request.getParameter("sessionId");
        HttpSession session = request.getSession();
        String sessionId = session.getId();
        if(StringUtil.isNotEmpty(tempSessionId) && !tempSessionId.equals(sessionId)){
            sessionId = tempSessionId;
            if(sessionMap.containsKey(sessionId)){
                session = sessionMap.get(sessionId);
            }
        }
        if(!sessionMap.containsKey(sessionId)){
            sessionMap.put(sessionId, session);
        }
        return session;
    }  
    private static final Map<String, HttpSession> sessionMap = new HashMap<String, HttpSession>();  
    public static HttpSession getSession(String sessionId){
        HttpSession session = sessionMap.get(sessionId);
        return session == null ? getSession() : session;
    }  
    public static void removeSession(String sessionId){
        if(sessionMap.containsKey(sessionId)){
            sessionMap.remove(sessionId);
        }
    }