package com.oreilly.struts.storefront.security;

import java.util.Locale;

import javax.servlet.http.*;

import org.apache.struts.action.*;

import com.oreilly.struts.storefront.customer.view.UserView;

import com.oreilly.struts.storefront.framework.exceptions.BaseException;

import com.oreilly.struts.storefront.framework.UserContainer;

import com.oreilly.struts.storefront.framework.StorefrontBaseAction;

import com.oreilly.struts.storefront.framework.util.IConstants;

import com.oreilly.struts.storefront.service.IStorefrontService;

/**

 * Implements the logic to authenticate a user for the Storefront application.

 */

public class LoginAction extends StorefrontBaseAction {

  /**

   * Called by the controller when the user attempts to log in to the

   * Storefront application.

   */

  public ActionForward execute( ActionMapping mapping,

                                ActionForm form,

                                HttpServletRequest request,

                                HttpServletResponse response )

  throws Exception{

    // The email and password should have already been validated by the ActionForm

    String email = ((LoginForm)form).getEmail(  );

    String password = ((LoginForm)form).getPassword(  );

    // Log in through the security service

    IStorefrontService serviceImpl = getStorefrontService(  );

    UserView userView = serviceImpl.authenticate(email, password);

    // Create a single container object to store user data

    UserContainer existingContainer = null;

    HttpSession session = request.getSession(false);

    if ( session != null ){

      existingContainer = getUserContainer(request);

      session.invalidate(  );

    }else{

      existingContainer = new UserContainer(  );

    }

    // Create a new session for the user

    session = request.getSession(true);

    // Store the UserView in the container and store the container in the session

    existingContainer.setUserView(userView);

    session.setAttribute(IConstants.USER_CONTAINER_KEY, existingContainer);

    // Return a Success forward

    return mapping.findForward(IConstants.SUCCESS_KEY);

  }

}

思考题？

所有线程共享一个Action类实例意味着什么？我们在编程中需要注意些什么呢？