1.完成用户登录功能。
2.完成注册功能。
3.主体利用Maven导入java中的jar包，使用Servlet实现前后端交互，使用mybatis以及注解，mysql进行数据保存，Tomcat服务器进行开发。
效果图
项目结构
代码
mapper(相对应注解)
package com.itheima.mapper;import com.itheima.pojo.User;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Select;public interface UserMapper { /** * 用户登陆根据用户和密码来查询用户对象 * @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); /** * 根据用户名来查询用户是否存在 * @param usernmae * @return */ @Select("select * from tb_user where username=#{username}") User selectByUsername(String usernmae); /** * 判断完是否存在后不存在再进行注册添加用户 * @param user */ @Insert("insert into tb_user values(null,#{username},#{password})") void add(User user);}pojo(实体类)
package com.itheima.pojo;public class User { private Integer id; private String username; private String password; public Integer getId() { return id; } 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 + '\'' + '}'; }}3.util(工具类)
package com.itheima.util;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;/** * * 工具类避免资源浪费多次加载 */public class SqlSessionFactoryUtils { private static SqlSessionFactory sqlSessionFactory; static { String resource = "mybatis-config.xml"; InputStream inputStream = null; try { inputStream = Resources.getResourceAsStream(resource); } catch (IOException e) { e.printStackTrace(); } sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } public static SqlSessionFactory getSqlSessionFactory() { return sqlSessionFactory; }}4.web（Servlet）
1.loginServlet
package com.itheima.web;import com.itheima.mapper.UserMapper;import com.itheima.pojo.User;import com.itheima.util.SqlSessionFactoryUtils;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;import java.io.PrintWriter;@WebServlet("/loginServlet")public class loginServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 1.接收用户名和密码 String username = request.getParameter("username"); String password = request.getParameter("password"); //2. 调用Mybatis完成查询 SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory(); //2.2获取SqlSession对象 SqlSession sqlSession =sqlSessionFactory.openSession(); //2.3获取Mapper UserMapper userMapper = sqlSession.getMapper(UserMapper.class); //2.4 调用方法 User user = userMapper.select(username, password); //2.5释放资源 sqlSession.close(); // 获取相对应的输出流 并设置content response.setContentType("text/html;charset=utf-8"); PrintWriter writer = response.getWriter(); //3.判断user是否为null if (user!=null){ //登陆成功 writer.write("登陆成功"); } else { //登陆失败 writer.write("登陆失败"); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }}2.registerServlet
package com.itheima.web;import com.itheima.mapper.UserMapper;import com.itheima.pojo.User;import com.itheima.util.SqlSessionFactoryUtils;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.接受用户数据 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); // 调用Mapper，根据用户名来查询是否 SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory(); //2.2获取SqlSession对象 SqlSession sqlSession =sqlSessionFactory.openSession(); //2.3获取Mapper UserMapper userMapper = sqlSession.getMapper(UserMapper.class); //2.4 调用方法 User u = userMapper.selectByUsername(username); if (u == null){ // 用户名不存在 userMapper.add(user); // 提交事务 sqlSession.commit(); response.setContentType("text/html;charset=utf-8"); response.getWriter().write("注册成功"); } else{ // 用户名不存在 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("用户已存在,注册失败"); } // 释放资源 sqlSession.close(); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }}5.html
1.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="/Tomcat-demo1/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>2.register.html
<!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="login.html">登录</a> </div> <form id="reg-form" action="/Tomcat-demo1/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>总结
此登陆注册界面使用Maven，Servlet，Mybatis，Mysql，Tomcat技术以及结合了html，css界面设置实现了前后端交互，将前端界面输入的数据传入到后端java中进行处理并将数据保存在mysql数据库之中，是个很不错的练手小项目，新入门小伙伴可以一起尝试。
基本代码如上所示，以上均为手敲，如需所有代码请私信我，谢谢！！！