整体就是mysql里存了一张表，然后在java程序里用mybatis把数据读出来的一个简单示例。

库 blog里有一张表 article

整个项目就是增加了这3个文件

首先是mybatis-config.xml文件

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/blog"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <!--写好的sql映射文件(EmployeeMapper.xml)注册到全局配置文件(mybatis-config.xml)中-->
    <mappers>
        <mapper resource="ArticleMapper.xml"/>
    </mappers>
</configuration>

然后是ArticleMapper.XML

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper">
    <select id="selectArticle" resultType="org.example.po.Article">
        select * from article where id = #{id}
    </select>
</mapper>

然后是和数据库存储模型对应的对象Article类

package org.example.po;

import java.util.Date;

public class Article {
    private Integer id;

    private String title;

    private String desc;

    private Integer cate;

    private Date createdAt;

    private Date updatedAt;

    private String content;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title == null ? null : title.trim();
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc == null ? null : desc.trim();
    }

    public Integer getCate() {
        return cate;
    }

    public void setCate(Integer cate) {
        this.cate = cate;
    }

    public Date getCreatedAt() {
        return createdAt;
    }

    public void setCreatedAt(Date createdAt) {
        this.createdAt = createdAt;
    }

    public Date getUpdatedAt() {
        return updatedAt;
    }

    public void setUpdatedAt(Date updatedAt) {
        this.updatedAt = updatedAt;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content == null ? null : content.trim();
    }
}

然后就是运行类，main方法

package org.example;

import com.google.gson.Gson;
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 org.example.po.Article;

import java.io.InputStream;

public class Main {
    public static void main(String[] args) throws Exception {
        String resource="mybatis-config.xml";
        InputStream inputStream= Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        Article article=sqlSession.selectOne("selectArticle",1);
        Gson gson=new Gson();
        System.out.println("Hello world!");

        System.out.println(gson.toJson(article));
    }
}

最后把pom.XML也贴一下

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>mybatis-study</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.9</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
        </dependency>

        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.10</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.30</version>
        </dependency>
    </dependencies>

</project>

其他问题可以参这个官方教程

mybatis – MyBatis 3 | XML 映射器