maven项目下Java 简单引入 Mtbatis

在pom.xml文件中配置mybatis坐标和数据库驱动：

<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.3.0</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>

在resources资源目录下新建两个文件和一个文件夹：db.properties、mybtais-config.xml和mapper文件夹
db.properties代码如下：

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/croom?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai  
jdbc.username=root
jdbc.password=root

mybtais-config.xml代码如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <properties resource="db.properties"></properties> <!--   数据库信息的配置文件 -->
    <settings>
        <setting name="cacheEnabled" value="false"/> 
    </settings>
    <typeAliases>
        <package name="entity"/> <!--   实体对象的包名 -->
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>
    <mappers><!--   映射的表与实体的配置文件-->
        <mapper resource="./mapper/UsersMapper.xml"></mapper>
    </mappers>
</configuration>

在src/main/java/entity文件下创建名为：User.java代码如下：

package entity;

public class User {
    private Long id;
    private String username;
    private String password;
    private String avater;
    private Integer role;
    private Integer department;
    private String xinqin;
    public User(){}
    public User(String username , String password, String avatar,Integer department,Integer role,String xinqin){
        this.username = username;
        this.password = password;
        this.avater = avatar;
        this.department = department;
        this.role = role;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long 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;
    }

    public String getAvatar() {
        return avater;
    }

    public void setAvatar(String avatar) {
        this.avater = avatar;
    }

    public Integer getDepartment() {
        return department;
    }

    public void setDepartment(Integer department) {
        this.department = department;
    }

    public Integer getRole() {
        return role;
    }

    public void setRole(Integer role) {
        this.role = role;
    }

    public String getXinqin(){
        return xinqin;
    }

    public void setXinqin(String xinqin){
        this.xinqin=xinqin;
    }
}

在src/main/java/mapper文件下创建名为：UsersMapper.java代码如下：

package mapper;

import entity.User;

import java.util.List;

public interface UsersMapper {
    /*
    * 查询全部用户
    * */
    List<User> selectAll();

    /*
    * 用户登录
    * */
    User checkLogin(String username);

    /*
    * 添加用户
    * */
    Integer insertUser(User user);

    /*
    * 用户名查找
    * */
    List<String> checkUsername(String username);

    /*
     * 用户名查找
     * */
    User loginUserName(String username);

    /*
    * 通过序号查找用户
    * */
    User findByUserID(Long id);

    /*
    * 用户修改
    * */
    Integer updateByUserId(User user);

    /*
    * 删除用户
    * */
    Integer deleteUser(Long id);

}

在src/main/java/serviceImp文件下创建名为：ImpUserMapper.java代码如下：

package server;

import entity.Friend;
import entity.User;
import mapper.UsersMapper;
import org.apache.ibatis.session.SqlSession;
import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.Test;
import util.MybatisUtil;


import java.util.List;

public class ImpUserMapper{

    public static SqlSession sqlSession = MybatisUtil.getSqlSession();

    public static UsersMapper userMapper = sqlSession.getMapper(UsersMapper.class);

    public static List<User> SelectAll(){
        List<User> lists = userMapper.selectAll();
        return lists;
    }

    public static User CheckLogin(String username){
        User user = userMapper.checkLogin(username);
        return user;
    }

    public static void InsertUser(User user){
        userMapper.insertUser(user);
        sqlSession.commit();
    }

    public  static void DeleteUser(Long id){
        userMapper.deleteUser(id);
        sqlSession.commit();
    }

    public static Boolean checkUsername(String name){
        List<String> lists = userMapper.checkUsername(name);
        if (lists == null || lists.size() ==0 ) return false;
        else return true;
    }

    public static List<User> checkUserdepart(Integer department){
        return userMapper.checkUserdepart(department);
    }

    public static User loginUserName(String username){
        return userMapper.loginUserName(username);
    }

    public static void updateByUserId(User user){
        userMapper.updateByUserId(user);
        sqlSession.commit();
    }
}

在src/main/java/resources/mapper文件下创建名为：UsersMapper.xml代码如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="mapper.UsersMapper">
    <select id="selectAll" resultType="User">
           select *from users
    </select>
    <select id="checkUsername" resultType="String" parameterType="String" flushCache="true"  useCache="false">
           select username from users where username = #{username} LIMIT 1
    </select>

    <select id="loginUserName" resultType="User" parameterType="String" flushCache="true"  useCache="false">
           SELECT * FROM users where username=#{username} LIMIT 1
    </select>
    <select id="checkLogin" resultType="User" flushCache="true" useCache="false">
           select *from users where username = #{username} LIMIT 1
    </select>
    <insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
           insert into users(username,password,avater,department,role,xinqin ) value (#{username},#{password},#{avater},#{department},#{role},#{xinqin})
    </insert>
    <select id="findByUserID" parameterType="Long"   resultType="entity.User">
            select * from users where id = #{id} LIMIT 1
    </select>

    <update id="updateByUserId"  parameterType="entity.User">
        UPDATE users
        <trim prefix="set" suffixOverrides=",">
            <if test="username!=null">username=#{username},</if>
            <if test="password!=null">password=#{password},</if>
            <if test="department!=null">department=#{department},</if>
            <if test="role!=null">role=#{role},</if>
            <if test="xinqin!=null">xinqin=#{xinqin},</if>
        </trim>
        WHERE id=#{id}
    </update>

    <delete id="deleteUser" parameterType="Long">
            delete from users where id = #{id}
    </delete>


</mapper>

通过测试就可以调通。