获取json:
    function dejson($str){
        $str = preg_replace('/\\\"([^"]*)\\\"/',"“$1”",$str);
        $str = stripslashes($str);
        $str = str_replace("\\", '\\\\', $str);
        $str = str_replace("\t", '\\t', $str);
        $str = str_replace("\r\n", '\n', $str);
        return json_decode($str, true);
    }
写入json:
    json_encode($arr,JSON_UNESCAPED_UNICODE);