实例：1，http://localhost/aaa/ (打开aaa中的index.php)结果：$_SERVER['QUERY_STRING'] = "";$_SERVER['REQUEST_URI']  = "/aaa/";$_SERVER['SCRIPT_NAME']  = "/aaa/index.php";$_SERVER['PHP_SELF']     = "/aaa/index.php";2，http://localhost/aaa/?p=222 (附带查询)结果：$_SERVER['QUERY_STRING'] = "p=222";$_SERVER['REQUEST_URI']  = "/aaa/?p=222";$_SERVER['SCRIPT_NAME']  = "/aaa/index.php";$_SERVER['PHP_SELF']     = "/aaa/index.php";3，http://localhost/aaa/index.php?p=222&q=333结果：$_SERVER['QUERY_STRING'] = "p=222&q=333";$_SERVER['REQUEST_URI']  = "/aaa/index.php?p=222&q=333";$_SERVER['SCRIPT_NAME']  = "/aaa/index.php";$_SERVER['PHP_SELF']     = "/aaa/index.php";由实例可知：$_SERVER["QUERY_STRING"]  获取查询 语句，实例中可知，获取的是?后面的值$_SERVER["REQUEST_URI"]   获取 http://localhost 后面的值，包括/$_SERVER["SCRIPT_NAME"]   获取当前脚本的路径，如：index.php$_SERVER["PHP_SELF"]      当前正在执行脚本的文件名   $_SERVER['REQUEST_URI']和$_SERVER["HTTP_X_REWRITE_URL"]的区别http://www.hujuntao.com/web/php/difference-between-server-request-uri-and-server-http_x_rewrite_url.html WordPress通过301重定向实现非首先域（非www）跳转向本来是一个很简单事情，由于没弄清楚$_SERVER['HTTP_X_REWRITE_URL'] 和$_SERVER['REQUEST_URI']的区别导致了循环重定向问题。现在来具体研究下$_SERVER['HTTP_X_REWRITE_URL'] 和$_SERVER['REQUEST_URI']的区别首先要纠正一部分的观点就是IIS+PHP不支持$_SERVER['REQUEST_URI']不是，不支持是PHP Version 版本的问题，php4.4.0不支持 $_SERVER['REQUEST_URI']，php5.2.5则增加了支持；$_SERVER['REQUEST_URI']常用来获当前URL例如：http://www.hujuntao.com/index.php?p=3$_SERVER['REQUEST_URI']获得的就是/index.php?p=3这部分。$_SERVER["HTTP_X_REWRITE_URL"]则在IIS下获得的是当前URL,在apache下的值为空例如：当前URL:http://www.hujuntao.com/IIS环境下：$_SERVER['REQUEST_URI'] = /index.php$_SERVER["HTTP_X_REWRITE_URL"] =/apache环境下：$_SERVER['REQUEST_URI'] = /$_SERVER["HTTP_X_REWRITE_URL"] =”当前URL：http://www.hujuntao.com/index.phpIIS环境下：$_SERVER['REQUEST_URI'] = /index.php$_SERVER["HTTP_X_REWRITE_URL"] =/index.phpapache环境下：$_SERVER['REQUEST_URI'] = /index.php$_SERVER["HTTP_X_REWRITE_URL"] =”