private function saveImg($txt){
        $path = './upload/file/ycode/imgs/';
        if(!file_exists($path))
            {
                if(mkdir($path,0777,true))
                {
                    $img ="http://qrtu.com/api.php?txt=".$txt ;

                    ob_clean();

                    ob_start();

                    readfile($img);     //读取图片

                    $img = ob_get_contents();   //得到缓冲区中保存的图片

                    ob_end_clean();     //清空缓冲区

                    $fp = fopen($path.$txt.'.jpg','w');  //写入图片

                    if(fwrite($fp,$img))

                    {
                      fclose($fp);
                    }
                }
        }
        return $path.$txt.'.jpg';
    }

ThinkPHP5调用生成二维码类生成二维码并保存到本地服务器

private function saveImg(){
        $path = './upload/file/yde/imgs/';
        header('Content-Type: image/png');
        header("Content-Type: text/html;charset=utf-8");
        vendor("phpqrcode.phpqrcode");//引入工具包
        $qRcode = new \QRcode();//实例化类
        if(!file_exists($path)){  
           mkdir($path, 0700,true);
        }
        $time = $content.'.png';//生成的二维码文件名
        $fileName = $path.$time;//1.拼装生成的二维码文件路径
        $level = 'L';  //3.纠错级别：L、M、Q、H 
        $size = 6;//4.点的大小：1到10,用于手机端4就可以了
        @ob_end_clean();//清空缓冲区
        $qRcode->png($content, $fileName, $level, $size);//生成二维码
        return $fileName;//返回文件路径
    }

Notice: ob_end_clean() [ref.outcontrol]: failed to delete buffer. No buffer to delete

解决方法一

@ob_end_clean();

解决方法二

if(ob_get_contents()) ob_end_clean();