案例:通过HttpSession判断用户是否登录
需求:实现登录一次即可,在一次会话内,可以反复多次访问WEB-INF/ welcome.html,如果没有登录过,跳转到登录页,登录成功后,可以访问
项目结构:
组件介绍:
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form method="get" action="loginServlet.do">
用户名:<input type="text" name="username" ><br/>
密码:<input type="password" name="password" ><br/>
<input type="submit" >
</form>
</body>
</html>
登录成功之后可以访问的资源
main.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
this is main page
</body>
</html>
LoginServlet
用来校验登录的,登录成功将用户信息存户HttpSession,否则回到登录页
package com.msb.servlet;
import com.msb.pojo.User;
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;
import java.io.IOException;
/**
* @Author: Ma HaiYang
* @Description: MircoMessage:Mark_7001
*/
@WebServlet(urlPatterns = "/loginServlet.do")
public class LoginServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 获取用户名和密码
String username = req.getParameter("username");
String password = req.getParameter("password");
// 如果用户名和密码为 msb 1234
if("msb".equals(username) && "1234".equals(password)){
// 将用户信息放在HTTPSession中
User user =new User(null, null, "msb", "1234");
HttpSession session = req.getSession();
session.setAttribute("user", user);
// 登录成功 跳转至 main.html
resp.sendRedirect(req.getContextPath()+"/mainServlet.do");
}else{
// 登录失败 回到login.html
resp.sendRedirect(req.getContextPath()+"/login.html");
}
}
}
MainServlet
用来向main.html中跳转的,同时验证登录,登录过,可以直接跳转,否则回到登录页
package com.msb.servlet;
import com.msb.pojo.User;
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;
import java.io.IOException;
import java.util.logging.Handler;
/**
* @Author: Ma HaiYang
* @Description: MircoMessage:Mark_7001
*/
@WebServlet(urlPatterns = "/mainServlet.do")
public class MainServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//跳转至main.html
HttpSession session = req.getSession();
User user = (User)session.getAttribute("user");
if(null != user){
// 判断如果登录过 允许跳转 HTTPSession中如果有登陆过的信息
req.getRequestDispatcher("/WEB-INF/main.html").forward(req,resp);
}else{
// 如果没有登录过 回到登录去登录 HTTPSession中如果有登陆过的信息
resp.sendRedirect("login.html");
}
}
}
User
用来存储一个用户的信息的实体类对象
public class User implements Serializable {
private Integer uid;
private String realname;
private String username;
private String pasword; 标签：登录,req,html,案例,Session,Cookie,import,servlet,javax From： https://www.cnblogs.com/2324hh/p/17217174.html