流程说明：
1、用户填写用户名，密码等信息，点击注册按钮，提交到Registervlet
2、在Register中使用MyBatis保存数据
3、保存前，需要判断用户名是否已经存在，根据用户名查询数据库
准备环境及一些登录界面的代码见上一个博客：
用户登录功能实现案例_夏志121的博客-CSDN博客
https://blog.csdn.net/m0_61961937/article/details/124862350?spm=1001.2014.3001.5502
UserMapper接口添加如下代码：
/** * 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 * @param user */ @Insert("insert into tb_user values(null,#{username},#{password})") void add(User user);
增加注册的静态页面到项目的webapp目录下
register.html代码：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>欢迎注册</title> <link href="css/register.css" rel="stylesheet"> </head> <body> <div class="form-div"> <div class="reg-content"> <h1>欢迎注册</h1> <span>已有帐号？</span> <a href="login1.html">登录</a> </div> <form id="reg-form" action="/Webapp/registerServlet" method="post"> <table> <tr> <td>用户名</td> <td class="inputs"> <input name="username" type="text" id="username"> <br> <span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span> </td> </tr> <tr> <td>密码</td> <td class="inputs"> <input name="password" type="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 value="注 册" type="submit" id="reg_btn"> </div> <br class="clear"> </form> </div> </body> </html>
register.html对应的register.css代码：
* { margin: 0; padding: 0; list-style-type: none; } .reg-content{ padding: 30px; margin: 3px; } a, img { border: 0; } body { background-image: url("../imgs/reg_bg_min.jpg") ; text-align: center; } 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; }
RegisterServlet代码：
import com.itheima.mapper.UserMapper; import com.itheima.pojo.User; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; import java.io.InputStream; @WebServlet("/registerServlet") public class RegisterServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1、接收用户密码 String username = request.getParameter("username"); String password = request.getParameter("password"); //封装用户对象 User user = new User(); user.setUsername(username); user.setPassword(password); //2、使用mapper,根据用户名查询用户对象 //2.1 获取SqlSessionFactory对象 String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); //2.2 获取SqlSession对象 SqlSession sqlSession = sqlSessionFactory.openSession(); //2.3 获取Mapper UserMapper userMapper = sqlSession.getMapper(UserMapper.class); //2.4使用方法 User u = userMapper.selectByUsername(username); //3、判断用户对象是否为null if( u == null){ // 用户名不存在，添加用户 userMapper.add(user); //提交事务 sqlSession.commit(); //释放资源 sqlSession.close(); } else { //用户名存在，给出提示信息 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("用户名已存在"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } }
执行结果：
注册成功示例，数据库就会存入相应的用户名和密码：
注册失败示例：
代码优化：
创建SqlSessionFactory代码优化下面的重复代码：
//2.1 获取SqlSessionFactory对象 String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
问题：
1、代码重复：使用工具类优化
2、SqlSessionFactory工厂只创建一次，不要重复创建：利于静态代码块特性优化
SqlSessionFactoryUtils工具类代码：
import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.IOException; import java.io.InputStream; public class SqlSessionFactoryUtils { private static SqlSessionFactory sqlSessionFactory; static { //静态代码块会随着类的加载而自动执行，且只执行一次 try { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static SqlSessionFactory getSqlSessionFactory() { return sqlSessionFactory; } }
将两个文件中的重复代码优化为下面代码：
SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
自此代码优化结束。
