public static void main(String[] args) {
    try {
        System.out.println(new File("C:\test a.xml").toURI().toURL());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

result.append(":");
    if (u.getAuthority() != null && u.getAuthority().length() > 0) {
        result.append("//");
        result.append(u.getAuthority());
    }

<scheme>:<scheme-specific-part>

URI         = scheme ":" hier-part [ "?" query ] [ "#" fragment ]

  hier-part   = "//" authority path-abempty
              / path-absolute
              / path-rootless
              / path-empty