if ( (_username == null) || (_username.length() == 0) ) {
String msg = sm.getString("jdbclm.nulluser");
throw new LoginException(msg);
}
String[] grpList = jdbcRealm.authenticate(_username, getPasswordChar());
if (grpList == null) { // JAAS behavior
String msg = sm.getString("jdbclm.loginfail", _username);
throw new LoginException(msg);
}