超全局变量 ======= PHP 中的许多预定义变量都是“超全局的”，这意味着它们在一个脚本的全部作用域中都可用。在函数或方法中无需执行 global $variable; 就可以访问它们。 $GLOBALS $_SERVER $_REQUEST $_POST $_GET $_FILES $_ENV $_COOKIE $_SESSION ~~~ echo $_SERVER['PHP_SELF']; echo "<br>"; echo $_SERVER['SERVER_NAME']; echo "<br>"; echo $_SERVER['HTTP_HOST']; echo "<br>"; echo $_SERVER['HTTP_REFERER']; echo "<br>"; echo $_SERVER['HTTP_USER_AGENT']; echo "<br>"; echo $_SERVER['SCRIPT_NAME']; $_SERVER["SERVER_ADDR"] => 服务器IP $_SERVER["SERVER_NAME"] => 服务器地址 ~~~ ~~~ $_GET[''] $_POST[''] ~~~