找不到Jfactory Class

Question

我有以下代码可供使用：

<?php
function getArticleDbImage($item){ 

            global $db;
            if(!$db){
                $db =&JFactory::getDBO();
            }
            //echo "dt: ".$item->created;
            $artclDatArr =  explode("-",$item->created);
            $plugin =& JPluginHelper::getPlugin('content','setimage');
            $pluginParams = new JParameter($plugin->params);
            $query = 'SELECT a.images FROM #__content AS a WHERE id=' . $item->id;
            $db->setQuery($query);
            $images = $db->loadRow();
            //print_r($images);
            $db_image_path      = $pluginParams->get('db_image_path', 'images/stories/db_images/');
            $add_default_img    = $pluginParams->get('add_default_img', '1');
            $default_img_url    = $pluginParams->get('default_img_url', '');
            if($images[0]){
                $imgNameArr = explode(".", $images[0]);
                $image = rtrim($db_image_path,'/') . "/" . $artclDatArr[0] . "/" . ltrim($artclDatArr[1],'0') . "/" . $imgNameArr[0] . '_e.' . $imgNameArr[1];
            } else {
                $image = $default_img_url;
            }
            //echo "img: ".$fn_image;
            return $image;

        }
           extract($_REQUEST);
        ?>

以上代码给出了错误：Jfactory class not found