还是在OutOfMemory上看到的一段代码，自己修改了一下，其中的unescape()函数值得学习和搜藏，另一点就是从Sina的iplookup库中获取地理位置等信息比较有用：

<?php
/**
* 获取客户端+服务端IP及地理位置信息 Sina iplookup
**/
//取得地理位置信息
function iplookup($ip=1){
	if($ip){ //客户端
		$userip = getClientIP(); //客户端IP
	}else{ //服务端
		$domain = $_SERVER['HTTP_HOST'];
		$userip = gethostbyname($domain);
	}
	//$userip = (getClientIP()=='127.0.0.1')?'107.170.214.214':getClientIP();
	//返回Sina地理位置信息
	$json=@file_get_contents('http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js&ip='.$userip);
	$patterns = array();
	$patterns[0] = '/var remote_ip_info = /';
	$patterns[1] = '/;/';
	$patterns[2] = '/\Wu/';
	$find = array();
	$find[0] = "";
	$find[1] = "";
	$find[2] = "%u";
	$json = preg_replace($patterns, $find, $json); //过滤多余字符
	$json_arr = json_decode($json,true);
	return $json_arr;
}
//获取客户端IP
function getClientIP(){
	if(getenv('HTTP_CLIENT_IP')&&strcasecmp(getenv('HTTP_CLIENT_IP'),'unknown')){
		$ip=getenv('HTTP_CLIENT_IP');
	}
	elseif(getenv('HTTP_X_FORWARDED_FOR')&&strcasecmp(getenv('HTTP_X_FORWARDED_FOR'),'unknown')){
		$ip=getenv('HTTP_X_FORWARDED_FOR');
	}
	elseif(getenv('REMOTE_ADDR')&&strcasecmp(getenv('REMOTE_ADDR'),'unknown')){
		$ip=getenv('REMOTE_ADDR');
	}
	elseif(isset($_SERVER['REMOTE_ADDR'])&&$_SERVER['REMOTE_ADDR']&&strcasecmp($_SERVER['REMOTE_ADDR'],'unknown')){
		$ip=$_SERVER['REMOTE_ADDR'];
	}
	$ip=preg_replace("/^([d.]+).*/","1",$ip);
	return $ip;
}
/**
* 模拟JS里的unescape
* echo unescape('%u4e2d%u56fd');
*/
function unescape($str) {
	$str = rawurldecode($str);
	preg_match_all("/(?:%u.{4})|.{4};|&#\d+;|.+/U", $str, $r);
	$ar = $r[0];
	foreach($ar as $k=>$v) {
		if(substr($v,0,2) == "%u"){
			$ar[$k] = iconv("UCS-2", "utf-8//IGNORE", pack("H4",substr($v,-4)));
		}
		elseif(substr($v,0,3) == ""){
			$ar[$k] = iconv("UCS-2", "utf-8", pack("H4",substr($v,3,-1)));
		}
		elseif(substr($v,0,2) == "&#"){
			echo substr($v,2,-1)."";
			$ar[$k] = iconv("UCS-2", "utf-8", pack("n",substr($v,2,-1)));
		}
	}
	return join("",$ar);
}

$iplookup = iplookup();	//iplookup()的参数为0则是获取服务器端IP，默认为获取客户端IP

echo "IP：".getClientIP()."<br>";
echo '返回状态：'.$iplookup['ret']."<br>";
echo 'IP范围Strat：'.$iplookup['start']."<br>";
echo 'IP范围End：'.$iplookup['end']."<br>";
echo '国家：'.unescape($iplookup['country'])."<br>";
echo '省份：'.unescape($iplookup['province'])."<br>";
echo '城市：'.unescape($iplookup['city'])."<br>";
echo '区/县：'.unescape($iplookup['district'])."<br>";
echo '线路：'.unescape($iplookup['isp'])."<br>";
echo '类型：'.$iplookup['type']."<br>";
echo '描写：'.$iplookup['desc']."<br>";
print_r($iplookup);

从Sina的iplookup库中获取结果后，需要先用preg_replace()函数过滤掉多余字符然后再交给json_decode()函数处理，而且其中数组下标为country、province、city、district、isp的内容是Unicode编码的，也可以用之前文章中说的方法进行解码（Unicode编码解码的PHP脚本[bak]）。