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
login.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>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。
时间： 2024-10-05 06:36:13