createAssetHandler function

Handler createAssetHandler({ String? defaultDocument, String rootPath = 'assets', MimeTypeResolver? contentTypeResolver, })

Creates a Shelf Handler that serves files from Flutter assets.

If requested resource does not exist and defaultDocument is specified, request path is checked for a resource with that name. If it exists, it is served.

Specify a custom contentTypeResolver to customize automatic content type detection.

If your assets are not in the standard assets directory, or you want to share only subtree of the assets path structure, you may use rootPath argument to set the root directory for your handler.

Implementation

Handler createAssetHandler(
    {String? defaultDocument,
    String rootPath = 'assets',
    MimeTypeResolver? contentTypeResolver}) {
  final mimeResolver = contentTypeResolver ?? _defaultMimeTypeResolver;

  return (Request request) async {
    final segments = [rootPath, ...request.url.pathSegments];

    String key = p.joinAll(segments);

    Uint8List? body;

    body = await _loadResource(key);

    if (body == null && defaultDocument != null) {
      key = p.join(key, defaultDocument);

      body = await _loadResource(key);
    }

    if (body == null) {
      return Response.notFound('Not Found');
    }

    final contentType = mimeResolver.lookup(key);

    final headers = {
      HttpHeaders.contentLengthHeader: '${body.length}',
      if (contentType != null) HttpHeaders.contentTypeHeader: contentType,
    };

    return Response.ok((request.method == 'HEAD') ? null : body,
        headers: headers);
  };
}