java - Get j_username before having authentication completed -

i constructed filter runs before "springsecurityfilterchain" , filter needs j_username dofilter method. unfortuntaly it's impossible use principal object , username throught getname() before end of successful authentication.
there other way j_username in first filter?

override

 public class exusernamepasswordauthenticationfilter extends usernamepasswordauthenticationfilter {   @override  public authentication attemptauthentication(httpservletrequest request, httpservletresponse response) throws authenticationexception {           final string username = request.getparameter("j_username");            // delegate logic           return super.attemptauthentication(request, response);    }  } 

in security config < http />

<bean id="exusernamepasswordauthfilter" class="..." />  <custom-filter ref="exusernamepasswordauthfilter" position="form_login_filter"/> 

http://docs.spring.io/spring-security/site/docs/3.1.x/reference/springsecurity-single.html#ns-custom-filters