很方便的后台ajax上传文件

<a href="javascript:void(0);" url="{:U('teacherd?id='.$vo['id'])}" class="teacherd" uid="{$vo.id}"><if condition="$vo.spstatus eq 0" >上传批阅<else /> 已批阅 </if></a>

            $(".teacherd").click(function () {
                var $this=$(this);
                var id = $(this).attr("uid");
                var url = $(this).attr('url');
                var p_id = "{:I('p_id')}";
                var display = 'none';
                var src = '';
                var content = '<div class="margin_left_10" style="margin:20px;"><input type="hidden" name="id" value="' + id + '" ><div class="form-item"><div class="controls"><label class="label">上传文件:<span class="check-tips" id="picture-size"></span></label><input type="file" id="upfile"><input type="hidden" name="photo" id="cover_id_picture_id"/><div class="upload-img-box"><div class="upload-pre-item"  style="display:' + display + ';"><img src="' + src + '"/></div></div></div></div></form></div>';
                layer.open({
                    type: 1,
                    title: '上传审批',
                    content: content,
                    closeBtn: 2,
                    area: ['350px', '250px'],
                    btn: '确定',
                    yes: function () {
                        var fd = new FormData();
                        var uname =  $('#upfile').val().split('.');   //获取上传文件名并拆封成数组(获取后缀)
                        if((uname[1] != 'docx') && ( uname[1] != 'doc')){
                            
                            alert(uname[1]);
                             return false;
                        }
                        fd.append("upload", 1);
                        fd.append("id", id);   //将id传入
                        fd.append("p_id",p_id);  //p_id
                        fd.append("upfile", $("#upfile").get(0).files[0]);
                        $.ajax({
                            url: "{:U('uploadss')}",
                            type: "POST",
                            processData: false,
                            contentType: false,
                            data: fd,
                            success: function (d) {
                                if(d.code == 200){
                                    $(".layui-layer-shade").hide();
                                    $(".layui-layer-page").hide();
                                    $(".bac").fadeIn();
                                    $(".bac1").html("上传成功")
                                    $this.html("已审批")
                                }else{
                                    $("#layui-layer-shade1").hide();
                                    $("#layui-layer1").hide();
                                    $(".bac").fadeIn();
                                    $(".bac1").html("上传失败")
                                }
//                                console.log(d);
                            }

                        })
                    }
                })
            });

$(".closeA").on("click",function(){
    $(".bac").fadeOut()
})
$(".layui-layer-btn0").on("click",function(){
    $(".layui-layer-shade").hide();
    $(".layui-layer-page").hide();
})

后台代码：

 /*
     * 上传审批
     * Carey
     */

    public function uploadss() {
        $id = $_POST['id'];   //id
        $p_id = $_POST['p_id'];

        $exam_listsDB = M('exam_lists');
        $username = $exam_listsDB->where(array('id' => $id))->getField('username');

        $username = iconv("UTF-8", "gb2312", $username); //转码utf8
        $saveName = $username . '_' . $p_id . '_' . $id;  //文件命名规则考场p_id_用户id;

        $rootpath = '../Public/Uploads/examsp/kc' . $p_id . '/';
        mkdir($rootpath, 0755);

        $upload = new ThinkUpload(); // 实例化上传类    
        $upload->maxSize = 3145728; // 设置附件上传大小    3M
        $upload->exts = array('application/msword', 'doc', 'docx'); // 设置附件上传类型
        $upload->rootPath = $rootpath; // 设置附件上传根目录    // 上传文件
        $upload->autoSub = TRUE;   //自动生成子目录
        $upload->subName = 'py';
        $upload->saveName = $saveName;   //根据p_id-id
        $upload->replace = TRUE; //存在同名是否覆盖 true覆盖

        $info = $upload->uploadOne($_FILES['upfile']);

        if (!$info) {// 上传错误提示错误信息        
            $redata = array(
                'code' => 303, 'info' => $info, 'files' => $_FILES, 'id' => $id, 'p_id' => $p_id, 'username' => $username,
            );
        } else {
            // 上传成功
            $info['savename'] = iconv("gb2312", "UTF-8", $info['savename']);   //转码utf8
            $cha_dourl['cha_dourl'] = 'Public/Uploads/examsp/' . $info['savepath'] . $info['savename'];
            $cha_dourl['sptime'] = time();
            $cha_dourl['spstatus'] = 1;
            /* 如果上传成功更新表单数据 */
            $upda = $exam_listsDB->where(array('id' => $id))->save($cha_dourl);
            if ($upda) {
                $redata = array(
                    'code' => 200, 'info' => $info, 'files' => $_FILES, 'id' => $id, 'p_id' => $p_id, 'upda' => $upda,
                );
            } else {
                $redata = array(
                    'code' => 404, 'info' => $info, 'files' => $_FILES, 'id' => $id, 'p_id' => $p_id, 'upda' => $upda,
                );
            }
        }
        $this->ajaxReturn($redata);
    }