jeecg中的一个上下文工具类获取request，session

通过调用其中的方法可以获取到request和session，调用方式如下：

HttpServletRequest request = ContextHolderUtils.getRequest();

HttpSession session = ContextHolderUtils.getSession();

ContextHolderUtils，这个类的源码如下：

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) */
public class ContextHolderUtils {
    /**
     * SpringMvc下获取request
     * 
     * @return
     */
    public static HttpServletRequest getRequest() {
        HttpServletRequest request = null;
        if (RequestContextHolder.getRequestAttributes()!=null) {
            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);
        }
    }

}