* thrown, should the loginContext.login() method fail.
*/
public Authentication authenticate(Authentication auth)
throws AuthenticationException {
if (auth instanceof UsernamePasswordAuthenticationToken) {
UsernamePasswordAuthenticationToken request = (UsernamePasswordAuthenticationToken) auth;
try {
//Create the LoginContext object, and pass our InternallCallbackHandler
LoginContext loginContext = new LoginContext(loginContextName, new InternalCallbackHandler(auth));
//Attempt to login the user, the LoginContext will call our InternalCallbackHandler at this point.
loginContext.login();
//create a set to hold the authorities, and add any that have already been applied.
Set authorities = new HashSet();
if (request.getAuthorities() != null) {
authorities.addAll(Arrays.asList(request.getAuthorities()));
}
//get the subject principals and pass them to each of the AuthorityGranters
Set principals = loginContext.getSubject().getPrincipals();
for (Iterator iterator = principals.iterator(); iterator.hasNext();) {
Principal principal = (Principal) iterator.next();
for (int i = 0; i < authorityGranters.length; i++) {
AuthorityGranter granter = authorityGranters[i];
Set roles = granter.grant(principal);
//If the granter doesn't wish to grant any authorities, it should return null.
if ((roles != null) && !roles.isEmpty()) {
for (Iterator roleIterator = roles.iterator(); roleIterator.hasNext();) {
String role = roleIterator.next().toString();
authorities.add(new JaasGrantedAuthority(role, principal));
}
}
}
}
//Convert the authorities set back to an array and apply it to the token.
JaasAuthenticationToken result = new JaasAuthenticationToken(request.getPrincipal(),
request.getCredentials(),
(GrantedAuthority[]) authorities.toArray(new GrantedAuthority[authorities.size()]), loginContext);
//Publish the success event
publishSuccessEvent(result);