PHP页面跳转

我们有时候需要获取当前页面的url地址

javascript实现：
    顶级窗口的地址:top.location.href
    当前窗口的地址:this.location.href

php实现：

    #测试网址:http://localhost/blog/testurl.php?id=5
    //获取域名或主机地址 
    echo $_SERVER['HTTP_HOST']."
"; #localhost
    //获取网页地址 
    echo $_SERVER['PHP_SELF']."
"; #/blog/testurl.php
    //获取网址参数 
    echo $_SERVER["QUERY_STRING"]."
"; #id=5
    //获取用户代理 
    echo $_SERVER['HTTP_REFERER']."
"; 
    //获取完整的url
    echo 'http://'.$_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