[java web基础]实现自动登录功能demo

来源：互联网发布：开淘宝店怎么样编辑：程序博客网时间：2024/06/05 06:49

主要思路就是：当用户访问网站的首页时，浏览器端会先检擦浏览器中存在的cookie中是否又登录的用户的用户名，如果有，则直接跳转至用户登录好的界面，如果没有，则重定向至登录界面，在服务器端创建该用户登录的cookie,响应时，将创建的cookie返回至浏览器端保存。

一：用户访问首页时检查cookie是否存在。

package ahpudong.com;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/index.do")public class index extends HttpServlet {    public index() {        super();    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        Cookie[] cookies=request.getCookies();        if(cookies!=null){            for(Cookie cookie:cookies){                String name=cookie.getName();                String value=cookie.getValue();                if("name".equals(name) && "chendong".equals(value)){                    request.setAttribute(name, value);                    request.getRequestDispatcher("user.view").forward(request, response);                    return;                }            }           }            response.sendRedirect("login.jsp");    }}

二：确定用户登录的cookie不存在，在手动登录的过程中创建用户登录cookie。

package ahpudong.com;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/login.do")public class login extends HttpServlet {    public login() {        super();    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html");        request.setCharacterEncoding("utf-8");        response.setCharacterEncoding("utf-8");        PrintWriter out = response.getWriter();        String name=request.getParameter("name");        String pwd=request.getParameter("pwd");        String login=request.getParameter("auto");        if("chendong".equals(name) && "123456".equals(pwd)){            if("on".equals(login)){                Cookie cookie=new Cookie("name","chendong");                cookie.setMaxAge(7*24*60*60);//有效期为一个星期                response.addCookie(cookie);                request.setAttribute("name",name);                request.getRequestDispatcher("user.view").forward(request, response);                           }        }else{            response.sendRedirect("login.jsp");        }    }}

三：登录成功时的视图层

package ahpudong.com;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/user.view")public class User extends HttpServlet {    public User() {        super();    }    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        processRequest(request,response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        processRequest(request,response);    }    public void processRequest(HttpServletRequest request,HttpServletResponse response)            throws ServletException, IOException{        response.setCharacterEncoding("utf-8");        PrintWriter out=response.getWriter();        String name=(String) request.getAttribute("name");        out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");        out.println("<HTML>");        out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");        out.println("  <BODY>");        out.println("<h1>"+"welcome "+name+" login"+"</h1>");        out.println("  </BODY>");        out.println("</HTML>");        out.flush();        out.close();        }}

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