邮箱登录

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package chapter03.servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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 chapter03.model.User;
 
/**
 * Servlet implementation class loginServlet
 */
public class loginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
        
    /**
     * @see HttpServlet#HttpServlet()
     */
    public loginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
 
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(request, response);
    }
 
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=GBK");
        String action = request.getParameter("action");
        if ("login".equals(action)){
            login(request, response);
        }
        else if ("check".equals(action)){
            check(request, response);
        }
        else if ("logout".equals(action)){
            logout(request, response);
        }
        else{
            unlogin(request, response);
        }
    }
     
    private void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String loginUrl = "/login.html";
        String fileUrl = "/login?action=check";
        HttpSession session = request.getSession();
        String userName = request.getParameter("user_name");
        String password = request.getParameter("login_password");
        // 验证用户ID和密码是否合法，略...
        ServletContext context = getServletContext();
        if (userName == null || userName.equals("")) {
            RequestDispatcher dispatcher = 
        context.getRequestDispatcher(loginUrl);
            response.setContentType("text/html;charset=GBK");
            dispatcher.forward(request, response);
            return;
        }
        // 登录成功，设置session中的属性
        else{
            User user = new User();
            user.setUserName(userName);
            session.setAttribute("User", user);
            RequestDispatcher dispatcher = context.getRequestDispatcher(fileUrl);
            dispatcher.forward(request, response);
        }
    }
    private void check(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        User user = (User)session.getAttribute("User");
        if (user == null) {  // 若未登陆，则先跳转到登录页面
            response.setContentType("text/html;charset=GBK");
            response.setHeader("Refresh", "3; URL=login.html");
            PrintWriter out = response.getWriter();
            out.println("<FONT color='red'>请先登录！</FONT><BR>");
            out.println("<FONT color='blue'>3秒后跳转到登录页面...</FONT>");
            out.close();
            return;
        }
        else if(user.getUserName().equals("sss"))
        {
            String loginURL = "login?action=login";
            String logoutURL = "login?action=logout";
            response.setContentType("text/html;charset=GBK");
            PrintWriter out = response.getWriter();
            out.println("<HTML><HEAD><TITLE>MailServlet：check</TITLE></HEAD>");
            out.println("<body>");
            out.println("当前用户为：" + user.getUserName());
            out.println("<p><p>");
            out.println("你的邮箱中有100封邮件");
            out.println("<p><p>");
            out.println("<a href='" + loginURL + "'>登陆</a>");
            out.println("<a href='" + logoutURL + "'>注销</a>");
            out.println("</body></html>");
            out.close();
        }
        else
        {
            String loginURL = "login?action=login";
            response.setContentType("text/html;charset=GBK");
            PrintWriter out = response.getWriter();
            out.println("<HTML><HEAD><TITLE>MailServlet：check</TITLE></HEAD>");
            out.println("<body>");
            out.println(user.getUserName() + "您好！");
            out.println("<p><p>");
            out.println("<FONT color='red'>您无权访问邮件系统。</FONT>");
            out.println("<p><p>");
            out.println("请重新<a href='" + loginURL + "'>登陆</a>邮件系统！！");
            out.println("</body></html>");
            out.close();
        }
    }
    private void logout(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        User user = (User)session.getAttribute("User");
        String name = user.getUserName();
        session.invalidate();
        String loginURL = "login?action=login";
        PrintWriter out = response.getWriter();
        out.println("<HTML><HEAD><TITLE>MailServlet：logout</TITLE></HEAD>");
        out.println("<body>");
        out.println(name + "，再见！");
        out.println("<p><p>");
        out.println("<a href='" + loginURL + "'>重新登录邮件系统</a>");
        out.println("</body></html>");
        out.close();
    }
     
    private void unlogin(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        String loginURL = "login?action=login";
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        out.println("<HTML><HEAD><TITLE>MailServlet：unlogout</TITLE></HEAD>");
        out.println("<body>");
        out.println("您好！");
        out.println("<p><p>");
        out.println("请您先<a href='" + loginURL + "'>登陆</a>邮件系统！");
        out.println("</body></html>");
        out.close();
    }
 
}
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