Comprehensive Guide to Using MyBatis‑Plus with Spring Boot

This article introduces MyBatis‑Plus, a powerful ORM plugin for Spring Boot users, and provides a complete walkthrough from project preparation to advanced features.

1. Quick Start

Prepare the environment (Spring Boot, Maven, JDK 1.8, MySQL) and optionally Nacos for service discovery.

Add the required Maven dependencies:

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.0</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.27</version>
</dependency>

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>3.5.0</version>
</dependency>

Configure the Spring Boot main class with @MapperScan and @EnableDiscoveryClient :

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@MapperScan("com.wjbgn.user.mapper")
@SpringBootApplication
public class RobNecessitiesUserApplication {
    public static void main(String[] args) {
        SpringApplication.run(RobNecessitiesUserApplication.class, args);
    }
}

Define the data source configuration (master‑slave example) in application.yml :

spring:
  datasource:
    dynamic:
      primary: master
      strict: false
      datasource:
        master:
          url: jdbc:mysql://127.0.0.1:3306/rob_necessities?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai
          username: root
          password: 123456
        slave_1:
          url: jdbc:mysql://127.0.0.1:3306/rob_necessities?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai
          username: root
          password: 123456

Optionally tune HikariCP settings for better performance.

2. Usage

2.1 Entity Annotations

MyBatis‑Plus provides annotations such as @TableName , @TableId , and @TableField to map Java classes to database tables.

@TableName("user")
public class UserDO {
    @TableId(value = "id", type = IdType.AUTO)
    private Long id;

    @TableField("nickname")
    private String nickname;

    private String realName;
}

The @TableId type attribute supports values like AUTO , NONE , INPUT , ASSIGN_ID , and ASSIGN_UUID for different primary‑key strategies.

2.2 CRUD

Define a service interface extending IService and an implementation extending ServiceImpl :

public interface IUserService extends IService
{}

public class UserServiceImpl extends ServiceImpl
implements IUserService {}

Define a mapper interface extending BaseMapper :

@Mapper
public interface UserMapper extends BaseMapper
{}

2.3 Pagination

Add the pagination interceptor configuration:

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@MapperScan("com.wjbgn.*.mapper*")
public class MybatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
}

2.4 Logical Delete

Configure global logical‑delete fields or use @TableLogic on entity fields:

mybatis-plus:
  global-config:
    db-config:
      logic-delete-field: isDelete
      logic-delete-value: 1
      logic-not-delete-value: 0

@TableLogic
private Integer isDelete;

2.5 Enum Mapping

Implement IEnum for custom enums and configure package scanning:

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum SexEnum implements IEnum
{
    MAN(1, "男"),
    WOMAN(2, "女");
    private Integer code;
    private String name;
    // getters and getValue()
}

Use the enum in the entity:

@TableField("sex")
private SexEnum sex;

2.6 Automatic Field Filling

Define a MetaObjectHandler implementation:

@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        this.strictInsertFill(metaObject, "createTime", LocalDateTime.class, LocalDateTime.now());
    }
    @Override
    public void updateFill(MetaObject metaObject) {
        this.strictUpdateFill(metaObject, "updateTime", LocalDateTime.class, LocalDateTime.now());
    }
}

2.7 Multi‑DataSource

Configure multiple masters, slaves, or different database types in application.yml and use the @DS annotation to switch data sources at class or method level:

@DS("slave_1")
public class UserServiceImpl extends ServiceImpl
implements IUserService {
    @DS("slave_1")
    public List
getList() { return this.list(); }
    @DS("master")
    public int saveUser(UserDO user) { return this.save(user) ? 1 : 0; }
}

3. Testing

Create the user table, implement a REST controller with endpoints for save, update, delete, list, and pagination, and verify that all features work as expected.

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private IUserService userService;
    // endpoints: /save, /update, /delete, /list, /page
}

The article also provides links to the full source code repository and additional resources.