var http = require('http');
var util = require('util');

/**
 * 根據 ip 獲取獲取地址信息
 */
var getIpInfo = function(ip, cb) {
    var sina_server = 'http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=json&ip=';
    var url = sina_server + ip;
    http.get(url, function(res) {
        var code = res.statusCode;
        if (code == 200) {
            res.on('data', function(data) {
                try {
                    cb(null, JSON.parse(data));
                } catch (err) {
                    cb(err);
                }
            });
        } else {
            cb({ code: code });
        }
    }).on('error', function(e) { cb(e); });
};

getIpInfo('220.181.111.85', function(err, msg) {
    console.log('城市: ' + msg.city);
    console.log('msg: ' + util.inspect(msg, true, 8));
})

城市: 徐州
{
    "ret": 1,
    "start": "49.68.0.0",
    "end": "49.68.255.255",
    "country": "中國",
    "province": "江蘇",
    "city": "徐州",
    "district": "",
    "isp": "電信",
    "type": "",
    "desc": ""
}

<?

$ip = "220.181.111.85";
$url = "http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=json&ip=$ip";
$data = file_get_contents($url);
$result = json_decode($data);
echo "城市:" . $result->city . "<br>";
print_r($result);

?>

城市:徐州
stdClass Object
(
    [ret] => 1
    [start] => 49.68.0.0
    [end] => 49.68.255.255
    [country] => 中國
    [province] => 江蘇
    [city] => 徐州
    [district] =>
    [isp] => 電信
    [type] =>
    [desc] =>
)