HTML+CSS登录界面，有数据库的登录验证

HTML

 1 <!DOCTYPE html>
 2 <html lang="zh-CN">
 3     <head>
 4         <meta charset="UTF-8" />
 5         <meta name="viewport" content="width=device-width, initial-scale=1.0" />
 6         <title>用户登录</title>
 7         <link rel="stylesheet" href="CSS/login.css" />
 8     </head>
 9     <body>
10     <form name="user" action="LoginServlet" method="post">
11         <div class="login">
12             <h2>用户登录</h2>
13             <div class="login_box">
14                 <input type="text" name="uid" id="uid" autocomplete="off"/><label>用户名</label>
15             </div>
16             <div class="login_box">
17                 <input type="password" name="password" id="password" autocomplete="off"/><label>密码</label>
18             </div>
19             <a href="#" onclick="document.user.submit();return false">
20             登录        
21             <span></span>
22             <span></span>
23             <span></span>
24             <span></span>
25             </a>
26         </div>
27         </form>
28     </body>
29 </html>

CSS

* {
    /* 初始化 清除页面元素的内外边距 */
    padding: 0;
    margin: 0;
    /* 盒子模型 */
    box-sizing: border-box;
}
body {
    /* 弹性布局 让页面元素垂直+水平居中 */
    display: flex;
    justify-content: center;
    align-items: center;
    /* 让页面始终占浏览器可视区域总高度 */
    height: 100vh;
    /* 背景渐变色 */
    background: linear-gradient(#141e30, #243b55);
}
.login {
    /* 弹性布局 让子元素称为弹性项目 */
    display: flex;
    /* 让弹性项目垂直排列 原理是改变弹性盒子的主轴方向 父元素就是弹性盒子 现在改变后的主轴方向是向下了 */
    flex-direction: column;
    /* 让弹性项目在交叉轴方向水平居中 现在主轴的方向是向下 交叉轴的方向是与主轴垂直 交叉轴的方向是向右 */
    align-items: center;
    width: 400px;
    padding: 40px;
    background-color: rgba(0, 0, 0, 0.2);
    box-shadow: 0 15px 25px rgba(0, 0, 0, 0.4);
}
.login h2 {
    color: #fff;
    margin-bottom: 30px;
}
.login .login_box {
    /* 相对定位 */
    position: relative;
    width: 100%;
}
.login .login_box input {
    /* 清除input框自带的边框和轮廓 */
    outline: none;
    border: none;
    width: 100%;
    padding: 10px 0;
    margin-bottom: 30px;
    color: #fff;
    font-size: 16px;
    border-bottom: 1px solid #fff;
    /* 背景颜色为透明色 */
    background-color: transparent;
}
.login .login_box label {
    position: absolute;
    top: 0;
    left: 0;
    padding: 10px 0;
    color: #fff;
    /* 这个属性的默认值是auto 默认是这个元素可以被点击 但是如果我们写了none 就是这个元素不能被点击 , 就好像它可见但是不能用 可望而不可即 */
    /* 这个就是两者的区别 */
    pointer-events: none;
    /* 加个过渡 */
    transition: all 0.5s;
}
/* :focus 选择器是当input获得焦点是触发的样式 + 是相邻兄弟选择器 去找与input相邻的兄弟label */
/* :valid 选择器是判断input框的内容是否合法,如果合法会执行下面的属性代码,不合法就不会执行,我们刚开始写布局的时候给input框写了required 我们删掉看对比 当没有required的话input框的值就会被认为一直合法,所以一直都是下方的样式 ,但是密码不会,密码框内的值为空,那么这句话局不合法,required不能为空 当我们给密码框写点东西的时候才会执行以下代码*/
.login .login_box input:focus + label,
.login .login_box input:valid + label {
    top: -20px;
    color: #03e9f4;
    font-size: 12px;
}
.login a {
    overflow: hidden;
    position: relative;
    padding: 10px 20px;
    color: #03e9f4;
    /* 取消a表现原有的下划线 */
    text-decoration: none;
    /* 同样加个过渡 */
    transition: all 0.5s;
}

.login a:hover {
    color: #fff;
    border-radius: 5px;
    background-color: #03e9f4;
    box-shadow: 0 0 5px #03e9f4, 0 0 25px #03e9f4, 0 0 50px #03e9f4,
        0 0 100px #03e9f4;
}
.login a span {
    position: absolute;
}
.login a span:first-child {
    top: 0;
    left: -100%;
    width: 100%;
    height: 2px;
    /* to right 就是往右边 下面的同理 */
    background: linear-gradient(to right, transparent, #03e9f4);
    /* 动画 名称 时长 linear是匀速运动 infinite是无限次运动 */
    animation: move1 1s linear infinite;
}
.login a span:nth-child(2) {
    right: 0;
    top: -100%;
    width: 2px;
    height: 100%;
    background: linear-gradient(transparent, #03e9f4);
    /* 这里多了个0.25s其实是延迟时间 */
    animation: move2 1s linear 0.25s infinite;
}
.login a span:nth-child(3) {
    right: -100%;
    bottom: 0;
    width: 100%;
    height: 2px;
    background: linear-gradient(to left, transparent, #03e9f4);
    animation: move3 1s linear 0.5s infinite;
}
.login a span:last-child {
    left: 0;
    bottom: -100%;
    width: 2px;
    height: 100%;
    background: linear-gradient(#03e9f4, transparent);
    animation: move4 1s linear 0.75s infinite;
}

@keyframes move1 {
    0% {
        left: -100%;
    }
    50%,
    100% {
        left: 100%;
    }
}
@keyframes move2 {
    0% {
        top: -100%;
    }
    50%,
    100% {
        top: 100%;
    }
}
@keyframes move3 {
    0% {
        right: -100%;
    }
    50%,
    100% {
        right: 100%;
    }
}
@keyframes move4 {
    0% {
        bottom: -100%;
    }
    50%,
    100% {
        bottom: 100%;
    }
}

LoginServlet

package servlet;

import java.io.IOException;
import java.sql.Connection;

import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;



/**
 * Servlet implementation class UserServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

    }
         
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=UTF-8");
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String date=sdf.format(new Date());        
        String uid=String.valueOf(request.getParameter("uid"));
        String pass=String.valueOf(request.getParameter("password"));
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url="jdbc:mysql://localhost:3306/family income and expenditure?&useSSL=false&serverTimezone=UTC";
            String username="root";
            String password="";
            Connection conn=DriverManager.getConnection(url,username,password);
            
            String sql="select * from user_info where uid='"+uid+"'and password='"+pass+"'";
            
            PreparedStatement ps=conn.prepareStatement(sql);
            ResultSet rs=ps.executeQuery();
            if(rs.next()) {
                System.out.println(date+"  "+uid+" "+"login");
                System.out.println();
                request.setAttribute("uid", uid);
                request.getRequestDispatcher("index.html").forward(request,response);//登录成功
            }else{             
                response.getWriter().write("<font style='color:red;font-size:35px'><div align='center'>"+
                "用户名或密码错误！5秒后自动跳转"+"</div>"+"</font>");
                response.getWriter().write("<div align='center'>"
                +"如果没有发生跳转，请点"+"<a href='login.html'>"+"这里"+"</div>");                
                response.setHeader("refresh", "5;url=login.html");//登录失败，重新登录
            }
        }catch(Exception e) {
            e.printStackTrace();
        }finally{
            
        }
    }
}

Code