ajax异步获取文件上传后的url

public function upload2(){
        // echo "
";
        // var_dump($_FILES);die;
        $fileName = $_FILES['file']['name'];//文件名
        $tmpName = $_FILES['file']['tmp_name'];//临时存放的目录
        $fileError = $_FILES['file']['error'];
        $fileType = $_FILES['file']['type'];
        $fileSize = $_FILES['file']['size'];

        if($fileError>0){
            switch($fileError){
                case 1:
                    echo "上传的文件超过了 php.ini 中 upload_max_filesize 选项限制的值";
                    break;
                case 2:
                    echo "上传文件的大小超过了 HTML 表单中 MAX_FILE_SIZE 选项指定的值";
                    break;
                case 3:
                    echo "文件只有部分被上传";
                    break;
                case 4:
                    echo "没有文件被上传";
                    break;
                case 6:
                    echo "找不到临时文件夹。PHP 4.3.10 和 PHP 5.0.3 引进";
                    break;
                case 7:
                    echo "文件写入失败。PHP 5.1.0 引进";
                    break;
            }
        }   
        $ext = pathinfo($fileName,PATHINFO_EXTENSION);//类型
        $saveName = date('Ymd').mt_rand(1,100).'.'.$ext;
        //生成保存路径
        $uploads = "/uploads/";
        $path = rtrim($uploads,'/')."/".date('Y/m/d/');
        if(!file_exists($path)){
            mkdir($path,0777,true);
        }
        $saveFile = $path .$saveName;
        if(move_uploaded_file($tmpName,$saveFile)){
            // echo "上传成功";
            $ret['message']="成功";
            $ret['status'] = 1;
            $ret['url'] = $saveFile;
            echo  json_encode($ret);
        }else{
            // echo "上传失败啊";
            $ret['message']="失败";
            $ret['status'] = 0;
            echo  json_encode($ret);
        }
    }