$redis = new Redis();

$redis->connect('127.0.0.1', 6379);   

//获取客户端真实ip地址

function get_real_ip(){

    static $realip;

    if(isset($_SERVER)){

        if(isset($_SERVER['HTTP_X_FORWARDED_FOR'])){

            $realip=$_SERVER['HTTP_X_FORWARDED_FOR'];

        }else if(isset($_SERVER['HTTP_CLIENT_IP'])){

            $realip=$_SERVER['HTTP_CLIENT_IP'];

        }else{

            $realip=$_SERVER['REMOTE_ADDR'];

        }

    }else{

        if(getenv('HTTP_X_FORWARDED_FOR')){

            $realip=getenv('HTTP_X_FORWARDED_FOR');

        }else if(getenv('HTTP_CLIENT_IP')){

            $realip=getenv('HTTP_CLIENT_IP');

        }else{

            $realip=getenv('REMOTE_ADDR');

        }

    }

    return $realip;

}  

//这个key记录该ip的访问次数 也可改成用户id

$key = get_client_ip();  //该Key记录访问的次数，目前是以IP为例，也可以把用户id作为key，如userid_123456

//限制次数为3次。

$limit = 3;  

$check = $redis->exists($key);

if($check){

    $redis->incr($key);

    $count = $redis->get($key);

    if($count > 3){

        exit('已经超出了限制次数');

    }

}else{

    $redis->incr($key);

    //限制时间为60秒

    $redis->expire($key,60);

}  

$count = $redis->get($key);

echo '第 '.$count.' 次请求';