public function upload() {

        $grouplist = getcache('grouplist','member');   //获取缓存中身份分组的列表

        if($this->isadmin==0 && !$grouplist[$this->groupid]['allowattachment']) return false;   //判断是否允许上传附件

        pc_base::load_sys_class('attachment','',0);   //加载attachment类

        $module = trim($_GET['module']);  //通过get方式获取模型

        $catid = intval($_GET['catid']);  //通过get方式获取catid

        $siteid = $this->get_siteid();   //获取站点ID

        $site_setting = get_site_setting($siteid);   //获取站点配置信息，这个函数在此模块中的公共函数global.func.php中可以找到

        $site_allowext = $site_setting['upload_allowext'];  //获取到允许的上传文件类型

        $attachment = new attachment($module,$catid,$siteid);   //实例化attachment类，就是上面刚刚提到的加载进来的类

        $attachment->set_userid($this->userid);  //调用attachment类的set_userid函数，确定是哪个用户上传的。

        $a = $attachment->upload('upload',$site_allowext);  //上传文件，具体的函数请查看attachment类。

        if($a){     //下面这些就是上传成功后的一些路径和文件名什么的了~

            $filepath = $attachment->uploadedfiles[0]['filepath'];

            $fn = intval($_GET['CKEditorFuncNum']);

            $this->upload_json($a[0],$filepath,$attachment->uploadedfiles[0]['filename']);

            $attachment->mkhtml($fn,$this->upload_url.$filepath,'');

        }

    }

<form method="post" enctype="multipart/form-data" action="/index.php?m=attachment&c=attachments&a=upload" id="uploadload" target="iframelogo">

        <input type="file" class="uploadtxt" name="upload" /><input type="submit" value="dianji" />

</form>