1.2 模型2和MVC

package org.sunxin.struts2.ch01.model2.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.sunxin.struts2.ch01.model2.UserBean;
import org.sunxin.struts2.ch01.model2.UserCheckBean;

public class ControllerServlet extends HttpServlet
{
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
request.setCharacterEncoding("GBK");
response.setContentType("text/html;charset=GBK");

String action = request.getParameter("action");

//如果用户没有登录，并且也不是提交登录信息，则向用户显示登录页面
if (!isValidated(request) && !("login".equals(action)))
{
gotoPage("login.jsp", request, response);
return;
}

//如果用户提交登录信息，则对用户登录信息进行验证
if ("login".equals(action))
{
UserBean user = new UserBean();
user.setName(request.getParameter("name"));
user.setPassword(request.getParameter("password"));

UserCheckBean uc = new UserCheckBean(user);

if (uc.validate())
{
HttpSession session = request.getSession();
// 将user对象保存到Session对象中，在welcome.jsp中通过
// 动作元素从Session中得到user对象
session.setAttribute("user", user);
// 验证成功，将请求转向welcome.jsp
gotoPage("welcome.jsp", request, response);
}
else
{
// 验证失败，将请求转向loginerr.jsp
gotoPage("loginerr.jsp", request, response);
}
}
// 对于其他的action请求，可在后面的else if...else语句中继续处理
/*
* else if { } else { }
*/
}

/**
* 判断用户是否已经登录了
*/
private boolean isValidated(HttpServletRequest request)
{
HttpSession session = request.getSession();
if (session.getAttribute("user") != null)
return true;
else
return false;
}

/**
* 将请求导向指定的页面
*/
private void gotoPage(String targetURL, HttpServletRequest request,
HttpServletResponse response) throws IOException, ServletException
{
RequestDispatcher rd;
rd = request.getRequestDispatcher(targetURL);
rd.forward(request, response);
}
}