Spring Boot 整合 MyBatis

Spring Boot 整合 MyBatis 是非常简单的，相比 Spring 整合减少了非常多的配置，几步就整合完成了

所涉及的环境

Intellij IDEA 2020.3.2
Spring Boot 2.3.1
JDK 1.8
Maven 3.6.3
MySQL 5.7

正文

创建 Spring Boot 工程就不再阐述了

创建表结构

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(10) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `password` varchar(10) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=79 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

添加 Maven 依赖（pom.xml）

<dependencies>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.1.0</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>

</dependencies>

编写实体类（cn.imzjw.entity.User.java）

@Data	// <- Lombok 插件，idea 2020 默认是装了，如未装，请删掉手动生成 setter、getter，或安装 Lombok
@AllArgsConstructor
@NoArgsConstructor
public class User implements Serializable {

    private Integer id;

    private String username;

    private String password;

    private static final long serialVersionUID = 1L;
}

编写持久层（cn.imzjw.mapper.UserMapper.java）

public interface UserMapper {

    /**
     * 查询所有 by garvey
     *
     * @return 结果
     */
    List<User> selectAll();
}

编写业务层（cn.imzjw.service.UserService.java）……

业务层实现类（cn.imzjw.service.impl.UserServiceImpl.java）……

这里就不贴出业务层的代码了，因为和持久层接口代码是一样的，项目也没什么业务逻辑，只是一个整合

下面就编写 mapper 映射文件（resources/mapper/UserMapper.xml）

<?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="cn.imzjw.mapper.UserMapper">

    <resultMap id="BaseResultMap" type="User">
        <id column="id" property="id"/>
        <result column="username" property="username"/>
        <result column="password" property="password"/>
    </resultMap>

    <sql id="Base_Column_List">
        id, username, `password`
    </sql>

    <select id="selectAll" resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List"/>
        FROM `user`
    </select>

</mapper>

编写 application.yml

spring:
  # 数据库配置
  datasource:
    url: jdbc:mysql:///mybatis?useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: root

mybatis:
  type-aliases-package: cn.imzjw.entity     # 开启别名
  mapper-locations: classpath:mapper/*.xml  # 映射文件路径

编写 Controller （cn.imzjw.controller.UserController.java）

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("list")
    public List<User> findAll() {
        return userService.selectAll();
    }
}

最后在主程序扫描 Mapper 层接口

@SpringBootApplication
@MapperScan("cn.imzjw.mapper") // 扫描 Mapper 层接口
public class SpringbootMybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootMybatisApplication.class, args);
    }

}