Servlet——Session会话mini项目

<span style="font-size:18px;"><span style="font-size:18px;">package myservlet;/* * Session 会话技术目的是服务器只能服务一个浏览器，防止非法登陆，运行在服务器端； */import java.io.*;import javax.servlet.*;import javax.servlet.http.*;public class Servlet1 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();    String erro= (String)request.getAttribute("error");            out.println("<form action='/Myservlet/Servlet2' method='post'>");out.println("<h1>欢迎登陆</h1>");out.println("用户名:<input type='text' name='userid'/><br/>");out.println("密  码:<input type='password' name='password'/><br/>");out.println("<input type='submit' value='登陆'>");out.println("验证码<img src=''/>");out.println("</from>"); if(erro!=null){     out.println("<h5 style='color:red'>"+erro+"</h5>");     }        }public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {        this.doGet(request, response);}}+++++++++++++++package myservlet;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;public class Servlet2 extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        request.setCharacterEncoding("utf-8");        HttpSession hs = request.getSession();                String userid = request.getParameter("userid");        String password = request.getParameter("password");        if("123".equals(password)){            out.println("<h3>恭喜你登陆成功</h3>");            hs.setAttribute("userid",userid);            hs.setAttribute("password", password);            request.getRequestDispatcher("/Servlet3").forward(request,response);        }else{            request.setAttribute("error","密码错误");            request.getRequestDispatcher("/Servlet1").forward(request,response);        }                    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        this.doGet(request, response);    }}++++++++++++++package campus1;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;public class Servelet3 extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        out.println("登陆成功");    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        this.doGet(request, response);         }} </span></span>