//------------------------------
       //by:∮明天去要飯
       //-------------------------------       
        string listclass = class.selectedvalue.tostring();
        dgmanage.datasource = bll.newsinfo.listallnews(listclass);
        try
        {
            dgmanage.databind();
        }
        catch
        {
            if (dgmanage.currentpageindex > 0)
            {
                dgmanage.currentpageindex -= 1;
                dgmanage.databind();
            }
        }