Let me lead with the fact that I don't understand Spring Web MVC well enough.
That said, I think I have some concerns with the CredentialsBinder API and its associated LoginController implementation.
LoginController extends Spring SimpleFormHandler and looks something like this:
LoginControler processFormSubmission excerpt
protected ModelAndView processFormSubmission(final HttpServletRequest request, final HttpServletResponse response, final Object object,
final BindException errors) throws Exception {
final Credentials credentials = (Credentials)object;
this.credentialsBinder.bind(request, credentials);
final String ticketGrantingTicketId = this.centralAuthenticationService.createTicketGrantingTicket(credentials);
We need to look carefully at the "object" argument. The object here is a Command. LoginController extends SimpleFormController which extends AbstractFormController which extends BaseCommandController.
LoginController defaults this Command class:
LoginController afterPropertiesSet() excerpt
public void afterPropertiesSet() throws Exception {
if (this.getCommandClass() == null) {
this.setCommandName("credentials");
this.setCommandClass(UsernamePasswordCredentials.class);
In BaseCommandController, we have:
BaseCommandController getCommand()
/**
* Retrieve a command object for the given request.
* <p>Default implementation calls createCommand. Subclasses can override this.
* @param request current HTTP request
* @return object command to bind onto
* @see #createCommand
*/
protected Object getCommand(HttpServletRequest request) throws Exception {
return createCommand();
}
BaseCommandController createCommand()
/**
* Create a new command instance for the command class of this controller.
* @return the new command instance
* @throws InstantiationException if the command class could not be instantiated
* @throws IllegalAccessException if the class or its constructor is not accessible
*/
protected final Object createCommand() throws InstantiationException, IllegalAccessException {
if (this.commandClass == null) {
throw new IllegalStateException("Cannot create command without commandClass being set - " + "either set commandClass or override formBackingObject");
}
if (logger.isDebugEnabled()) {
logger.debug("Creating new command of class [" + this.commandClass.getName() + "]");
}
return this.commandClass.newInstance();
}
Current CredentialsBinder interface
/**
* Interface for a class that can bind items stored in the request to a particular
* credentials implementation. This allows for binding beyond the basic
* JavaBean/Request parameter binding that is handled by Spring automatically.
*/
public interface CredentialsBinder {
/**
* Method to allow manually binding attributes from the request object to properties of
* the credentials. Useful when there is no mapping of attribute to property for the
* usual Spring binding to handle.
*
* @param request The HttpServletRequest from which we wish to bind credentials to
* @param credentials The credentials we will be doing custom binding to.
*/
void bind(HttpServletRequest request, Credentials credentials);
/**
*
* Method to determine if a CredentialsBinder supports a specific class or not.
*
* @param clazz The class to determine is supported or not
* @return true if this class is supported by the CredentialsBinder, false otherwise.
*/
boolean supports(Class clazz);
}