Java-web实现用户登录、注册功能

java 前端 servlet 2023-10-10 08:10:23 807人浏览泡泡鱼

摘要

源码在资源里目录环境搭建数据库用户登录需求分析代码实现编写UserMapper类编写User类编写loginServlet类编写login.html编写login.css

源码在资源里

环境搭建

在编写代码之前，在pom.xml导入servlet、mybatis的依赖，导入Tomcat插件。
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数据库

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用户登录

需求分析

在前端页面输入用户名和密码，点击登录，将数据提交给servlet。
在servlet中编写程序，实现接收前端提交的用户名和密码。
在servlet中通过Mybatis框架调用Mapper查询，返回结果封装成一个User对象并返回
判断User对象是否为null，是null登录失败、不是null登录成功。

代码实现

编写UserMapper类

编写UserMapper提供根据用户名、密码查询用户数据方法方法

public interface UserMapper {        @Select("select* from tb_user where username =#{username} and passWord = #{password}")    User select(@Param("username") String username, @Param("password") String password);}

编写User类

public class User {    private Integer id;    private String username;    private String password;    public void setId(Integer id) {        this.id = id;    }    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;    }    @Override    public String toString() {        return "User{" +                "id=" + id +                ", username='" + username + '\'' +                ", password='" + password + '\'' +                '}';    }}

编写loginServlet类

@WEBServlet("/loginServlet")public class loginServlet extends httpservlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //第一步：接收用户名、密码        String username;        username= req.getParameter("username");        String password;        password= req.getParameter("password");        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);        username = new String(bytes, StandardCharsets.UTF_8);        byte[] bytes1 = password.getBytes(StandardCharsets.ISO_8859_1);        password = new String(bytes1, StandardCharsets.UTF_8);        //第二步：调用Mybatis查询用户        //工具类sqlSessionFactoryUtil调用方法返回sqlSessionFactory        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtil.getSqlSessionFactory();        //  获取sqlSession对象，执行sql        SqlSession sqlSession = sqlSessionFactory.openSession();        //获取UserMapper接口的代理对象        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        //获取方法        User user = mapper.select(username, password);        sqlSession.close();        //获取字符的输出流 设置content-type        resp.setContentType("text/html;charset=utf-8");        PrintWriter writer = resp.getWriter();        //第三步：判断        if(user!=null){            //登陆成功            writer.write("登录成功");        }else {            //登录失败            writer.write("登录失败");        }    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        this.doGet(req, resp);    }}

编写login.html

DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>logintitle>    <link href="CSS/login.css" rel="stylesheet">head><body><div id="loginDiv">    <fORM action="/Web-Demo/loginServlet" method="post" id="form">        <h1 id="loginMsg">LOGIN INh1>        <p>UserName:<input id="username" name="username" type="text">p>        <p>PassWord:<input id="password" name="password" type="password">p>        <div id="subDiv">            <input type="submit" class="button" value="login up">            <input type="reset" class="button" value="reset">               <a href="reGISter.html">没有账号？点击注册a>        div>    form>div>body>html>

编写login.css

* {    margin: 0;    padding: 0;}html {    height: 100%;    width: 100%;    overflow: hidden;    margin: 0;    padding: 0;    background: url(../imgs/BackGround.JPG) no-repeat 0px 0px;    background-repeat: no-repeat;    background-size: 100% 100%;    -moz-background-size: 100% 100%;}body {    display: flex;    align-items: center;    justify-content: center;    height: 100%;}#loginDiv {    width: 37%;    display: flex;    justify-content: center;    align-items: center;    height: 300px;    background-color: rgba(75, 81, 95, 0.3);    box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);    border-radius: 5px;}#name_trip {    margin-left: 50px;    color: red;}p {    margin-top: 30px;    margin-left: 20px;    color: Azure;}input {    margin-left: 15px;    border-radius: 5px;    border-style: hidden;    height: 30px;    width: 140px;    background-color: rgba(216, 191, 216, 0.5);    outline: none;    color: #f0edf3;    padding-left: 10px;}#username{    width: 200px;}#password{    width: 202px;}.button {    border-color: cornsilk;    background-color: rgba(100, 149, 237, .7);    color: aliceblue;    border-style: hidden;    border-radius: 5px;    width: 100px;    height: 31px;    font-size: 16px;}#subDiv {    text-align: center;    margin-top: 30px;}#loginMsg{    text-align: center;color: aliceblue;}

用户注册

需求分析

在前端页面输入用户名和密码，点击注册，将数据提交给servlet。
在servlet中编写程序，实现接收前端提交的用户名和密码。
在servlet中通过Mybatis框架调用Mapper查询，返回结果封装成一个User对象并返回
判断User对象是否为null，是null调用mapper添加用户、不是null代表用户已存在。

代码编写

编写UserMapper类

编写UserMapper提供根据用户名查询用户数据方法和添加用户方法

public interface UserMapper {        @Select("select* from tb_user where username =#{username}")    User selectByUsername(String username);        @Select("insert into tb_user values(null,#{username},#{password})")    void add(User user);}

编写registerServlet类

@WebServlet("/registerServlet")public class registerServlet extends HttpServlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //第一步：接收用户名、密码        String username;        String password;        username= req.getParameter("username");        password= req.getParameter("password");        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);        username = new String(bytes, StandardCharsets.UTF_8);        byte[] bytes1 = password.getBytes(StandardCharsets.ISO_8859_1);        password = new String(bytes1, StandardCharsets.UTF_8);        //封装用户对象        User user1 = new User();        user1.setUsername(username);        user1.setPassword(password);        //第二步：调用Mybatis查询用户        //加载Mybatis的核心配置文件        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtil.getSqlSessionFactory();        //  获取sqlSession对象，执行sql        SqlSession sqlSession = sqlSessionFactory.openSession();        //获取UserMapper接口的代理对象        UserMapper mapper = sqlSession.getMapper(UserMapper.class);        //获取方法        User user = mapper.selectByUsername(username);        //获取字符的输出流 设置content-type        resp.setContentType("text/html;charset=utf-8");        PrintWriter writer = resp.getWriter();        //第三步：判断        if(user==null){            //用户名不存在，添加用户            mapper.add(user1);            //提交事务            sqlSession.commit();            sqlSession.close();        }else {            //用户存在，给出提示信息            writer.write("用户已存在");        }    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        this.doGet(req, resp);    }}

编写register.html

采用正则表达式实现用户名不超过15个字符、密码在4~10个字符。采用上个案例的注册界面。

DOCTYPE html><html><head>    <meta charset="utf-8">    <title>欢迎注册title>    <link rel = "stylesheet" href="css/register.css">head><body><div class = "form-div">    <div class="reg-content">        <h1>欢迎注册h1>        <span>已有账号？span>        <a href="login.html">登录a>    div>    <form id = "reg-form" action="/Web-Demo/registerServlet" method="post">        <table>            <tr>                <td>用户名：td>                <td class="inputs">                    <input type="text" name = "username" id="username"/>                    <br>                    <span id = "username_err" class="err_msg" style="display:none">用户名不符合规则span>                td>            tr>            <tr>                <td>密码：td>                <td class="inputs">                    <input type="password" name = "password" id = "password"/>                    <br>                    <span id="password_err" class="err_msg" style="display: none">密码格式有误span>                td>            tr>        table>        <div class="buttons">            <input type = "submit" value="注册" id ="reg_btn" />        div>        <br class="clear">    form>div><script>    //验证用户名    var usernameInput = document.getElementById("username");    usernameInput.onblur = checkUser;    function checkUser(){        var username = usernameInput.value.trim();        //判断用户名是否符合规则：长度0~15 单词字符组成        var reg = /^\w{0,15}$/;        var flag= reg.test(username);        if(flag){            document.getElementById("username_err").style.display = "none";        }else{            document.getElementById("username_err").style.display = "";        }        return flag;    }    //验证密码    var passwordInput = document.getElementById("password");    passwordInput.onblur = checkPassword;    function checkPassword(){        var password = passwordInput.value.trim();        var reg = /^\w{4,10}$/;        var flag= reg.test(password);        if(flag){            document.getElementById("password_err").style.display = "none";        }else{            document.getElementById("password_err").style.display = "";        }        return flag;    }script>body>html>

编写register.css

* {    margin: 0;    padding: 0;    list-style-type: none;}.reg-content{    padding: 30px;    margin: 3px;}a, img {    border: 0;}body {    background-image: url("../imgs/BackGround.JPG") ;    no-repeat:center center fixed;        -webkit-background-size: cover;    -o-background-size: cover;    background-size: cover;    display: flex;    align-items: center;    justify-content: center;    height: 100%;}table {    border-collapse: collapse;    border-spacing: 0;}td, th {    padding: 0;    height: 90px;}.inputs{    vertical-align: top;}.clear {    clear: both;}.clear:before, .clear:after {    content: "";    display: table;}.clear:after {    clear: both;}.form-div {    background-color: rgba(255, 255, 255, 0.27);    border-radius: 10px;    border: 1px solid #aaa;    width: 424px;    margin-top: 150px;    margin-left:1050px;    padding: 30px 0 20px 0px;    font-size: 16px;    box-shadow: inset 0px 0px 10px rgba(255, 255, 255, 0.5), 0px 0px 15px rgba(75, 75, 75, 0.3);    text-align: left;}.form-div input[type="text"], .form-div input[type="password"], .form-div input[type="email"] {    width: 268px;    margin: 10px;    line-height: 20px;    font-size: 16px;}.form-div input[type="checkbox"] {    margin: 20px 0 20px 10px;}.form-div input[type="button"], .form-div input[type="submit"] {    margin: 10px 20px 0 0;}.form-div table {    margin: 0 auto;    text-align: right;    color: rgba(64, 64, 64, 1.00);}.form-div table img {    vertical-align: middle;    margin: 0 0 5px 0;}.footer {    color: rgba(64, 64, 64, 1.00);    font-size: 12px;    margin-top: 30px;}.form-div .buttons {    float: right;}input[type="text"], input[type="password"], input[type="email"] {    border-radius: 8px;    box-shadow: inset 0 2px 5px #eee;    padding: 10px;    border: 1px solid #D4D4D4;    color: #333333;    margin-top: 5px;}input[type="text"]:focus, input[type="password"]:focus, input[type="email"]:focus {    border: 1px solid #50afeb;    outline: none;}input[type="button"], input[type="submit"] {    padding: 7px 15px;    background-color: #3c6db0;    text-align: center;    border-radius: 5px;    overflow: hidden;    min-width: 80px;    border: none;    color: #FFF;    box-shadow: 1px 1px 1px rgba(75, 75, 75, 0.3);}input[type="button"]:hover, input[type="submit"]:hover {    background-color: #5a88c8;}input[type="button"]:active, input[type="submit"]:active {    background-color: #5a88c8;}.err_msg{    color: red;    padding-right: 170px;}#password_err,#tel_err{    padding-right: 195px;}#reg_btn{    margin-right:50px; width: 285px; height: 45px; margin-top:20px;}

编写SqlSessionFactory工具类

在写Servlet的时候，因为需要使用Mybatis来完成数据库的操作，所
以对于Mybatis的基础操作就出现了些重复代码：

String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(inputStream);

有了这些重复代码就会造成一些问题:

重复代码不利于后期的维护
SqlSessionFactory工厂类进行重复创建，资源消耗非常大但性能却非常低。
代码重复可以抽取工具类
对指定代码只需要执行一次可以使用静态代码块

对于静态代码块会随着类的加载而自动执行同时加载，只执行一次，就很好解决这一问题。

public class SqlSessionFactoryUtil {//SqlSessionFactory工具类抽取    private static SqlSessionFactory sqlSessionFactory;    static {        //静态代码块会随着类的加载而加载 只执行一次        //加载Mybatis的核心配置文件        String resource = "mybatis-config.xml";        InputStream resourceAsStream = null;        try {            resourceAsStream = Resources.getResourceAsStream(resource);        } catch (IOException e) {            e.printStackTrace();        }        //  获取sqlSessionFactory对象        sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);   }    public static SqlSessionFactory getSqlSessionFactory (){        return sqlSessionFactory;    }}