PHP判断是不是https协议

function is_HTTPS(){  //判断是不是https

             if(!isset($_SERVER['HTTPS']))  return FALSE;  

             if($_SERVER['HTTPS'] === 1){  //Apache  

                 return TRUE;  

             }elseif($_SERVER['HTTPS'] === 'on'){ //IIS  

                 return TRUE;  

             }elseif($_SERVER['SERVER_PORT'] == 443){ //其他  

                 return TRUE;  

             }  

                 return FALSE;  

    }