您的位置: 首页  >  IT文章  >  点击页面先登录，登录后继续事先页面

点击页面先登录，登录后继续事先页面

分类: IT文章 • 2023-11-13 12:24:18
点击页面先登录，登录后继续之前页面


    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。


点击页面先登录，登录后继续事先页面


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


点击页面先登录，登录后继续事先页面


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


点击页面先登录，登录后继续事先页面


登录页面


点击页面先登录，登录后继续事先页面


我的订单页面


点击页面先登录，登录后继续事先页面


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。




相关推荐