PHP代码检测web环境是否开启mod_rewrite模块

记录一下使用php代码检测当前web环境是否支持rewrite，支持IIS,APACHE,NGINX

function mod_rewrite(){
/**
 * --------------------------------------------------------------
 * MOD REWRITE CHECK
 * --------------------------------------------------------------
 * Define Constant for MOD REWRITE
 * 
 * Check if server allows MOD REWRITE. Checks for both 
 * Apache and IIS.
 * 
 */
if( function_exists('apache_get_modules') && in_array('mod_rewrite',apache_get_modules()) )
   return TRUE;
elseif( isset($_SERVER['IIS_UrlRewriteModule']) )
   return TRUE;
else
   return FALSE;
}
mod_rewrite();