PHP调用新浪查询IP归属地

<?php
$ip = "218.192.3.42";
$json = file_get_contents("http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=json&ip=".$ip);
$json = json_decode($json, true);
echo "IP地址：".$ip;
echo "归属地：".$json["country"].$json["province"].$json["city"].$json["district"].$json["isp"];
?>