1、起步依赖

文档SpringBoot版本为2.5.4

<dependency>
     <groupId>org.mybatis.spring.boot</groupId>
     <artifactId>mybatis-spring-boot-starter</artifactId>
     <version>2.2.0</version>
</dependency>

2、数据库表脚本

CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE = utf8_bin ROW_FORMAT = Dynamic;
INSERT INTO `user` VALUES (1, '百里慕溪', 20);
SET FOREIGN_KEY_CHECKS = 1;

3、配置数据源

spring:
  datasource:
    url: jdbc:mysql:///mylean  #jdbc:mysql:/// == jdbc:mysql://localhost:3306
    username: dbuser
    password: root
    driver-class-name: com.mysql.jdbc.Driver

4、代码测试

1、注解开发方式

1.实体类

package com.itlean.domain;

/**
 * @describe:
 * @author: weny.yang
 * @date: 2021-09-06 19:38
 */
public class User {

    private int id;
    private String name;
    private int age;

    get/set...

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

?2.Mapper接口

package com.itlean.mapper;

import com.itlean.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface UserMapper {

    @Select("select * from user")
    public List<User> findAll();

}

3.测试类

package com.itlean;

import com.itlean.domain.User;
import com.itlean.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class ApplicationTests {

    @Autowired
    private UserMapper userMapper;
    
    @Test
    void findAll() {
        List<User> userList = userMapper.findAll();
        System.out.println(userList);
    }

}

输出：

?????????说明整合ok，但是控制台提醒`com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'.意思说我们使用的mysql驱动太老本淘汰了，建议我们使用最新的，于是乎我们换上最新的，则不再报提醒：

spring:
  datasource:
    url: jdbc:mysql:///mylean  #jdbc:mysql:/// == jdbc:mysql://localhost:3306
    username: dbuser
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver #com.mysql.jdbc.Driver版本老旧，淘汰

?如果报如下错误，说明是时区问题，并且控制台也有对应的提示，图片太大，分开截图如下：

?使用提示内给出的字段名，为mysql数据源进行配置如下即可：

spring:
  datasource:
    url: jdbc:mysql:///mylean?serverTimezone=UTC  #jdbc:mysql:/// == jdbc:mysql://localhost:3306   UTC:标准时区
    username: dbuser
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver #com.mysql.jdbc.Driver版本老旧，淘汰

2、XML开发方式

1.Mapper接口类

package com.itlean.mapper;

import com.itlean.domain.User;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface UserXmlMapper { //名字随意取的，为了和上文注解开发区分开
    public List<User> findAll();
}

2.XML配置

在resources目录下新建文件夹，命名mapper，在mapper下面新建UserMapper.xml，mybatis的基本配置语法和规范本文不再赘述，如有欠缺请自行补课：

<?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="com.itlean.mapper.UserXmlMapper">
    <select id="findAll" resultType="user">
        select * from user
    </select>
</mapper>

3.添加Mybatis配置

mybatis:
  mapper-locations: classpath:mapper/*Mapper.xml    #mapper映射文件路径
  type-aliases-package: com.itlean.domain           #别名对应类所在包路径
  # config-location:    # 指定mybatis的核心配置文件，本次是简单演示，并没有配置

4.测试类

package com.itlean;

import com.itlean.domain.User;
import com.itlean.mapper.UserMapper;
import com.itlean.mapper.UserXmlMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class ApplicationTests {

    @Autowired
    private UserXmlMapper userXMLMapper;
    
    @Test
    void findAll() {
        List<User> userList = userXMLMapper.findAll();
        System.out.println(userList);
    }

}

输出：