configuration-CustomConfigurationAction-processAction.java

@Override
public void processAction(PortletConfig portletConfig, ActionRequest actionRequest, ActionResponse actionResponse) throws Exception {
	super.processAction(portletConfig, actionRequest, actionResponse);

	// Get current preference of portlet
	String portletResource = ParamUtil.getString(actionRequest, "portletResource");
	PortletPreferences preferences = PortletPreferencesFactoryUtil.getPortletSetup(actionRequest, portletResource);

	// Get value of parameter(s)
	String greeting = ParamUtil.getString(actionRequest, "greeting");

	// Add parameter's value into preference
	preferences.setValue("greeting", greeting);

	// Store
	preferences.store();

	// Send successful message
	SessionMessages.add(actionRequest, "success");
}