Liferay comes packaged with two login mechanisms: the login action in portal.impl’s com.liferay.portal.action.LoginAction and the login portlet in com.liferay.portlet.login. You should extend the portlet if you want to customize your own login portlet.You can extend the portal login using the new Liferay Hooks feature or the extension environment.

One thing I discovered while developing the sample Spring portlet: jar file conflicts between the plugin portlet and Liferay are a big headache. If Liferay has a version different from the one in your plugin, expect some very strange, confusing exception errors. Its Best to just make sure you only include the jars you need [...]

I’ve placed a simple, Hello World type Spring portlet in the downloads section. Check it out. It uses the Spring ParameterizableViewController to forward to the view JSP.