PHP手册-强制客户端认证

if (!isset($_SERVER['PHP_AUTH_USER'])) {
	header('WWW-Authenticate: Basic realm="My Realm"');
	header('HTTP/1.0 401 Unauthorized');
	echo 'Text to send if user hits Cancel button';
	exit;
} else {
	echo "
Hello {$_SERVER['PHP_AUTH_USER']}.
";
	echo "
You entered {$_SERVER['PHP_AUTH_PW']} as your password.
";
}