点击页面先登录，登录后继续之前页面

来源：互联网发布：netdvr客户端软件编辑：程序博客网时间：2024/04/30 11:53

登录诸如当当网之类的购物网站，未登录前可以先将产品放入购物车，当点击结账的时候会先跳出登录页面，登录后，继续跳至结账页面。一直想写一个类似的demo，终于昨天写了一个，记录下来。

先看代码吧，看完再讲代码。

代码块

后台

包含两个servlet，一个domain对象。

CheckLogin.java

package com.login;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;/** * Servlet implementation class CheckLogin */@WebServlet("/res/viaLogin")public class CheckLogin extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public CheckLogin() {        super();    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();User user = (User)session.getAttribute("user");String url = request.getParameter("url");if (!"".equals(url)) {session.setAttribute("url", url);}if (null != user){request.getRequestDispatcher("myOrder.jsp").forward(request, response);} else {request.getRequestDispatcher("login.jsp").forward(request, response);}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}}

LoginServlet.java

package com.login;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;/** * Servlet implementation class LoginServlet */@WebServlet("/res/login")public class LoginServlet extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public LoginServlet() {        super();    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();User user = new User();session.setAttribute("user", user);String url = (String) session.getAttribute("url");if (null == url || "".equals(url)) {request.getRequestDispatcher("main.jsp").forward(request, response); } else {request.getRequestDispatcher(url).forward(request, response);}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}}

User.java

package com.login;public class User {}

前台页面

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Register</title></head><body><center><form action="login"><table><caption>登陆</caption><tr><td>username</td><td><input name="username" /></td></tr><tr><td>password</td><td><input name="password" type="password"/></td></tr><tr><td colspan="2" align="center"><input type="submit" value="Submit" /></td></tr></table></form></center></body></html>

main.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Main</title></head><body><center> This is main jsp <br><br><a href="#" onclick="myOrder(this)">我的订单</a><br><br><a href="login.jsp">登陆</a></center><script type="text/javascript">function myOrder(obj) {    var url = "myOrder.jsp";        window.location.href = "viaLogin?url=" + url;}</script></body></html>

myOrder.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>MyOrder</title></head><body><center><h1>我的订单，登陆后可见</h1></center></body></html>

页面效果

主页面

登录页面

我的订单页面

代码讲解

首页面包含内容

<center> This is main jsp <br><br><a href="#" onclick="myOrder(this)">我的订单</a><br><br><a href="login.jsp">登陆</a></center><script type="text/javascript">function myOrder(obj) {    var url = "myOrder.jsp";        window.location.href = "viaLogin?url=" + url;}</script>

其中点击我的订单时，请求登录验证，同时将我的订单页面的URL传递至后台。

登录验证servlet CheckLogin.java

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();User user = (User)session.getAttribute("user");String url = request.getParameter("url");if (!"".equals(url)) {session.setAttribute("url", url);}if (null != user){request.getRequestDispatcher("myOrder.jsp").forward(request, response);} else {request.getRequestDispatcher("login.jsp").forward(request, response);}}

先获取session，然后在session中获取该user对象。

同时，将URL后面的参数项url，即本应该跳转到的页面保存在session中。

若user对象不为空，则直接跳转至我的订单myOrder.jsp页面；如果user为空，则跳转至登录页面login.jsp页面。

登录servlet LoginServlet.java

/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();User user = new User();session.setAttribute("user", user);String url = (String) session.getAttribute("url");if (null == url || "".equals(url)) {request.getRequestDispatcher("main.jsp").forward(request, response); } else {request.getRequestDispatcher(url).forward(request, response);}}

登录处理，new一个user出来，这里只是做示例，没有给user定义属性信息等，将user保存在session中，同时从session中获取到之前存放的url。

判断 url是否为null 或空字符串：

如果是null或空字符串，则说明上一步的操作就是登录操作，这时候跳转至主页面main.jsp；

如果url不为null，则说明上一步应该是在访问某个页面，但是因为没有登录，被拦截到了登录页面，此时登录后，就应该继续之前的请求。

以上例子疏于整理，校验，如有不详尽之处，烦请提出，后面必改正，谢谢。

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