RewriteCond %{REQUEST_URI} !^\.html$
RewriteRule ^(.*)\.html$ $2 [R=301,L]

if ( !function_exists('add_action') ) {
	header('Status: 403 Forbidden');
	header('HTTP/1.1 403 Forbidden');
	exit();
}

if ( !class_exists('ChangePermalinkHelper') ) {
	class ChangePermalinkHelper {
		
		/**
		 * Constructor
		 */
		function ChangePermalinkHelper() {
			
			add_action( 'plugins_loaded', array( &$this, 'onLoad' ) );
		}
		
		
		function onLoad() {
			
			if ( is_admin() )
				return;
				
			add_action( 'template_redirect', array( &$this, 'is404' ) );
		}
		
		/**
		 * return header message
		 */
		function is404() {
			global $wpdb;
			
			if ( !is_404() )
				return;
			
			$slug = htmlspecialchars( basename( $_SERVER['REQUEST_URI'] ) );
			$id = $wpdb->get_var( 
					$wpdb->prepare( "
						SELECT ID 
						FROM $wpdb->posts
						WHERE post_name = '%s'
						AND post_status = 'publish'
					", $slug )
				);
			
			if ($id) {
				$url = get_permalink( $id );
				header( 'HTTP/1.1 301 Moved Permanently' );
				header( 'Location: ' . $url );
			} else {
				return true;
			}
			
		}
		
	} // end class
	
	$ChangePermalinkHelper = new ChangePermalinkHelper();
}