代码：
<?php
//获取来自搜索引擎入站关键词
//by www.jb200.com
function get_keyword($url,$kw_start)
{
$start=stripos($url,$kw_start);
$url=substr($url,$start+strlen($kw_start));
$start=stripos($url,'&');
if ($start>0)
{
$start=stripos($url,'&');
$s_s_keyword=substr($url,0,$start);
}
else
{
$s_s_keyword=substr($url,0);
}
return $s_s_keyword;
}
$url=isset($_SERVER['HTTP_REFERER'])?$_SERVER['HTTP_REFERER']:'';//获取入站url。
$search_1="google.com"; //q= utf8
$search_2="baidu.com"; //wd= gbk
$search_3="yahoo.cn"; //q= utf8
$search_4="sogou.com"; //query= gbk
$search_5="soso.com"; //w= gbk
$search_6="bing.com"; //q= utf8
$search_7="youdao.com"; //q= utf8
$google=preg_match("/b{$search_1}b/",$url);//记录匹配情况，用于入站判断。
$baidu=preg_match("/b{$search_2}b/",$url);
$yahoo=preg_match("/b{$search_3}b/",$url);
$sogou=preg_match("/b{$search_4}b/",$url);
$soso=preg_match("/b{$search_5}b/",$url);
$bing=preg_match("/b{$search_6}b/",$url);
$youdao=preg_match("/b{$search_7}b/",$url);
$s_s_keyword="";
$bul=$_SERVER['HTTP_REFERER'];
//获取没参数域名
preg_match('@^(?:http://)?([^/]+)@i',$bul,$matches);
$burl=$matches[1];
//匹配域名设置
$curl="www.jb200.com";
if($burl!=$curl){
if ($google)
{//来自google
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。
$s_s_keyword=urldecode($s_s_keyword);
$urlname="谷歌：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
}
else if($baidu)
{//来自百度
$s_s_keyword=get_keyword($url,'wd=');//关键词前的字符为"wd="。
$s_s_keyword=urldecode($s_s_keyword);
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="百度：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else if($yahoo)
{//来自雅虎
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。
$s_s_keyword=urldecode($s_s_keyword);
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="雅虎：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else if($sogou)
{//来自搜狗
$s_s_keyword=get_keyword($url,'query=');//关键词前的字符为"query="。
$s_s_keyword=urldecode($s_s_keyword);
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="搜狗：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else if($soso)
{//来自搜搜
$s_s_keyword=get_keyword($url,'w=');//关键词前的字符为"w="。
$s_s_keyword=urldecode($s_s_keyword);
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="搜搜：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else if($bing)
{//来自必应
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。
$s_s_keyword=urldecode($s_s_keyword);
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="必应：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else if($youdao)
{//来自有道
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。
$s_s_keyword=urldecode($s_s_keyword);
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk
$urlname="有道：";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
else{
$urlname=$burl;
$s_s_keyword="";
$_SESSION["urlname"]=$urlname;
$_SESSION["s_s_keyword"]=$s_s_keyword;
}
$s_urlname=$urlname;
$s_urlkey=$s_s_keyword;
}
else{
$s_urlname=$_SESSION["urlname"];
$s_urlkey=$_SESSION["s_s_keyword"];
}
?>
说明：在处理时，记得处理好编码的问题，因为不同的搜索引擎，返回的结果，有的可能是GBK，有的则可能是UTF-8格式的内容。
函数2，这个也不错，大家可以试试。
代码如下：