session 案例实现验证用户登录

首页：

<!DOCTYPE html>
<html>
  <head>
    <title>login.html</title>
	
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>
  
  <body>
    <form action="/web2/servlet/LoginServlet" method="post">
    	用户名：<input type="text" name="username"><br>
    	密    码：<input type="password" name ="password"><br>
    <input type="submit" value="登录">
    
    
    
    
    
    </form>
  </body>
</html>

user对象

package cn.itcast.shoping;

public class User {
	private String username;
	private String password;
	
	
	public User(String username, String password) {
		super();
		this.username = username;
		this.password = password;
	}
	public User() {
		super();
		// TODO Auto-generated constructor stub
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	
}

用户登录的servlet

package cn.itcast.shoping;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setCharacterEncoding("utf-8");//第一句，设置服务器端编码
		response.setContentType("text/html;charset=utf-8");//第二句，设置浏览器端解码
		PrintWriter writer = response.getWriter();
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		List<User> list = Db.getall();
		for (User user :list){
			if(user.getUsername().equals(username) &&user.getPassword().equals(password)){
				request.getSession().setAttribute("user", user);//登录成功，向session中存入一个登录标记
				
				response.sendRedirect("/web2/index.jsp");
				return;
			}
		}
		writer.println("登录的用户名密码不正确");
		
	}


	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}



class Db{
	public static List list = new ArrayList();
	static {
		list.add(new User("aaa","123"));
		list.add(new User("bbb","123"));
		list.add(new User("ccc","123"));
		
	}
	
	public static List getall(){
		return list;
	}
	
	
	
	
}

登录成功跳转的页面：

<%@page import="com.sun.xml.internal.bind.v2.schemagen.xmlschema.Import"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
         欢迎你:$(user.username )<a href="/web2/login.html">登录</a><a href="/web2/servlet/LogoutServlet">退出登录</a>
  </body>
</html>

注销登录的servlet

package cn.itcast.shoping;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


//完成用户注销
public class LogoutServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		HttpSession session = request.getSession(false);
		if(session==null){
			response.sendRedirect("/seb2/index.jsp");
			return;
			
		}
		session.removeAttribute("user");
		response.sendRedirect("/seb2/index.jsp");
	
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}

session 案例实现验证用户登录

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