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
  • 用户注册
    • 需求分析
    • 代码编写
      • 编写UserMapper类
      • 编写registerServlet类
      • 编写register.html
      • 编写register.css
  • 编写SqlSessionFactory工具类
  • 项目总体架构
  • 运行展示
  • 案例图片

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。

数据库

用户登录

需求分析

  1. 在前端页面输入用户名和密码，点击登录，将数据提交给servlet。
  2. 在servlet中编写程序，实现接收前端提交的用户名和密码。
  3. 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
  4. 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 {/** *根据用户名 密码 查询用户 * @param username * @param password * @return */@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

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;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +'}';}}

编写loginServlet类

编写loginServlet类

@WebServlet("/loginServlet")public class loginServlet extends HttpServlet {@Overrideprotected 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sqlSessionFactorySqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtil.getSqlSessionFactory();//获取sqlSession对象，执行sqlSqlSession 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-typeresp.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");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req, resp);}}

编写login.html

编写login.html

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>login</title><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 IN</h1><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

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

  1. 在前端页面输入用户名和密码，点击注册，将数据提交给servlet。
  2. 在servlet中编写程序，实现接收前端提交的用户名和密码。
  3. 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
  4. 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 {/** * 根据用户名查询用户对象 * @param username * @return */@Select("select* from tb_user where username =#{username}")User selectByUsername(String username);/** * 添加用户 */@Select("insert into tb_user values(null,#{username},#{password})")void add(User user);}

编写registerServlet类

@WebServlet("/registerServlet")public class registerServlet extends HttpServlet {@Overrideprotected 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sqlSqlSession 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-typeresp.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");}}@Overrideprotected 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;/*兼容浏览器版本*/-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 = newSqlSessionFactoryBuilder().build(inputStream);

有了这些重复代码就会造成一些问题:

  1. 重复代码不利于后期的维护

  2. SqlSessionFactory工厂类进行重复创建，资源消耗非常大但性能却非常低。

  3. 代码重复可以抽取工具类

  4. 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;}}

工具类抽取以后，以后在对Mybatis的SqlSession进行操作的时候，就可以直接使用。

项目总体架构

运行展示

用户登录：

登录成功：

来一个登录失败的案例：admin用户不存在

登录失败：

注册admin用户：

注册成功，后端数据库已写入admin用户数据

案例图片

漂亮~~