私有方法四

/**
     * @author : lKF35745
     * @version: 1.0
     * <p>时间 : 2011-1-7</p>
     * <p>描述 : 根据子会议ID查询出子会议的所有上级会议ID</p>
     * <p>Copyright 1988-2005, Huawei Tech. Co., Ltd.</p>
     * @param conferenceID 会议ID
     * @return List<String> 子会议的上级会议ID
     */
    
    private List<String> findParentNodeByConferenceID(String conferenceID,
            CascadeTopoTree cascadeTree)
    {
        
        if (logger.isDebugEnabled())
        {
            logger.debug("begin to findParentNodeByConferenceID and param is "
                    + conferenceID);
        }
        
        if (null == conferenceID)
        {
            logger.warn("ConferenceID is null.");
            return null;
        }
        //存储子会议上级的会议ID
        List<String> conferenceIdList = new ArrayList<String>();
        //实例化一个拓扑树对象
        CascadeTopoTree cascadeTopoTree = cascadeTree;
        
        //查询该子会议是否在
        SubConferenceNode subConferenceNode = cascadeTopoTree
                .findSubConferenceNode(conferenceID);
        
        if (null == subConferenceNode)
        {
            logger.warn("this conferenceID is not in  CascadeTopoTree.");
            return null;
        }
        //得到子会议的上级会议ID
        SubConferenceNode parentConferenceNode = null;
        parentConferenceNode = subConferenceNode.getParentConferenceNode();
        
        //把自己添加到集合中
        conferenceIdList.add(subConferenceNode.getConferenceID());
        
        //循环取出子会议的上级会议
        while (null != parentConferenceNode)
        {
            conferenceIdList.add(parentConferenceNode.getConferenceID());
            parentConferenceNode = parentConferenceNode
                    .getParentConferenceNode();
            
            if (null == parentConferenceNode)
            {
                break;
            }
        }
        if (conferenceIdList.size() < 1)
        {
            logger.warn("ParentConferenID size is < 1");
            return null;
        }
        
        if (logger.isDebugEnabled())
        {
            logger.debug("end to findParentNodeByConferenceID");
        }
        
        return conferenceIdList;
    }