php获取当前URL和跳转前URL

php获取当前URL的相关代码
<?php echo $_SERVER['SERVER_NAME']?>      localhost80
<?php echo $_SERVER["SERVER_PORT"]?>    manager/products/
<?php echo $_SERVER["REQUEST_URI"]?>    product.php
URL: http : / / www.baidu.com/product/index.php
$_SERVER['HTTP_HOST']＝＝'www .baidu .com'        一个是主机地址
$_SERVER['PHP_SELF']＝＝'/product/index.php'      一个是脚本文件的绝对路径
/**/
获取跳转前的URL
$_SERVER ['HTTP_REFERER']