Exemplo de portlet do Liferay *SUPER* simples ;)

HelloYouPortlet.java

package com.liferayinaction.portlet;

import java.io.IOException;

import javax.portlet.ActionRequest;
import javax.portlet.ActionResponse;
import javax.portlet.GenericPortlet;
import javax.portlet.PortletException;
import javax.portlet.PortletMode;
import javax.portlet.PortletPreferences;
import javax.portlet.PortletRequestDispatcher;
import javax.portlet.PortletURL;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class HelloYouPortlet extends GenericPortlet {

  private static Log _log = LogFactory.getLog(HelloYouPortlet.class);

  protected String editJSP;

  protected String viewJSP;

  public void init() throws PortletException {
    editJSP = getInitParameter("edit-jsp");
    viewJSP = getInitParameter("view-jsp");
  }

  public void doView(RenderRequest renderRequest, RenderResponse renderResponse) throws IOException, PortletException {
    PortletPreferences prefs = renderRequest.getPreferences();
    String username = (String) prefs.getValue("name", "no");
    if (username.equalsIgnoreCase("no")) {
      username = "";
    }
    renderRequest.setAttribute("userName", username);
    include(viewJSP, renderRequest, renderResponse);
  }

  protected void include(String path, RenderRequest renderRequest, RenderResponse renderResponse) throws IOException, PortletException {
    PortletRequestDispatcher portletRequestDispatcher = getPortletContext().getRequestDispatcher(path);
    if (portletRequestDispatcher == null) {
      _log.error(path + " is not a valid include");
    } else {
      portletRequestDispatcher.include(renderRequest, renderResponse);
    }
  }

  public void doEdit(RenderRequest renderRequest, RenderResponse renderResponse) throws IOException, PortletException {
    renderResponse.setContentType("text/html");
    PortletURL addNameURL = renderResponse.createActionURL();
    addNameURL.setParameter("addName", "addName");
    renderRequest.setAttribute("addNameURL", addNameURL.toString());
    include(editJSP, renderRequest, renderResponse);
  }

  public void processAction(ActionRequest actionRequest, ActionResponse actionResponse) throws IOException, PortletException {
    String addName = actionRequest.getParameter("addName");
    if (addName != null) {
      PortletPreferences prefs = actionRequest.getPreferences();
      prefs.setValue("name", actionRequest.getParameter("username"));
      prefs.store();
      actionResponse.setPortletMode(PortletMode.VIEW);
    }
  }
}

O que isso faz? Recebe um nome de um input e exibe uma página com a mensagem Hello nomeDoInput. Extremamente simples não? :D