PHP URL变量

#测试网址:     http://localhost/blog/testurl.php?id=5

//获取域名或主机地址
echo $_SERVER["HTTP_HOST"]."<br>"; #localhost

//获取网页地址
echo $_SERVER["PHP_SELF"]."<br>"; #/blog/testurl.php

//获取网址参数
echo $_SERVER["QUERY_STRING"]."<br>"; #id=5

//获取用户代理
echo $_SERVER["HTTP_REFERER"]."<br>";

//获取完整的url
echo "http://".$_SERVER["HTTP_HOST"].$_SERVER["REQUEST_URI"];
echo "http://".$_SERVER["HTTP_HOST"].$_SERVER["PHP_SELF"]."?".$_SERVER["QUERY_STRING"];
#http://localhost/blog/testurl.php?id=5

//包含端口号的完整url
echo "http://".$_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
#http://localhost:80/blog/testurl.php?id=5

//只取路径
$url="http://".$_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
echo dirname($url);
#http://localhost/blog