Java-Web front-end and back-end interaction to achieve login registration (with source code)

1. Complete the user login function.

2. Complete the registration function.

3. The main body uses Maven to import the jar package in java, uses Servlet to realize front-end and back-end interaction, uses mybatis and annotations, mysql for data storage, and Tomcat server for development.

renderings

project structure

the code

mapper (corresponding annotation)

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 (entity class)

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 (tool class)

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>

Summarize

This login registration interface uses Maven, Servlet, Mybatis, Mysql, Tomcat technology and combines html and css interface settings to realize front-end and back-end interaction, and transfer the data input from the front-end interface to the back-end java for processing and save the data in mysql In the database, it is a very good practice project, and newcomers can try it together.

The basic code is as shown above, and the above are all hand-knocked, if you need all the codes, please private message me, thank you! ! !

Java-Web front-end and back-end interaction to achieve login registration (with source code)

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