private static DirContext getDirContext() {
    Hashtable<String, String> env = new Hashtable<>();
    env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
    env.put(Context.PROVIDER_URL, "ldap://" + serverIpAddress + ":" + Integer.toString(serverLdapPort));
    env.put(Context.SECURITY_AUTHENTICATION, "simple");
    env.put(Context.SECURITY_PRINCIPAL, connectionUsername + "@" + serverDomain);
    env.put(Context.SECURITY_CREDENTIALS, connectionPassword);
    try {
        return new InitialDirContext(env);
    } catch (NamingException e) {
        return null;
    }
}


    public static boolean authenticate(String username, String password) {
    connectionUsername = username;
    connectionPassword = password;
    DirContext dirContext = getDirContext();
    if (dirContext != null) {
        closeDirContext(dirContext);
        return true;
    } else {
        return false;
    }
}