Java

2023-12-22 15:35| 来源: 网络整理| 查看: 265

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。在这里插入图片描述

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 { /** *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; } @Override public 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 { @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

编写login.html

DOCTYPE html> login LOGIN IN UserName: PassWord: ;;; 没有账号？点击注册编写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 { /** * 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 { @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> 欢迎注册欢迎注册已有账号？登录用户名：用户名不符合规则密码：密码格式有误 //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; } 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 = 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; } }

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

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