Comprehensive Guide to MyBatis‑Plus CRUD, Configuration, and Advanced Features in Spring Boot

This guide starts by creating a MySQL database named mybatis_plus and a user table with fields id, name, age, and email. The table definition includes primary key and comments for each column.

DROP TABLE IF EXISTS user;
CREATE TABLE user (
  id BIGINT(20) NOT NULL COMMENT '主键ID',
  name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
  age INT(11) NULL DEFAULT NULL COMMENT '年龄',
  email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
  PRIMARY KEY (id)
);
INSERT INTO user (id, name, age, email) VALUES
  (1, 'Jone', 18, '[email protected]'),
  (2, 'Jack', 20, '[email protected]'),
  (3, 'Tom', 28, '[email protected]'),
  (4, 'Sandy', 21, '[email protected]'),
  (5, 'Billie', 24, '[email protected]');

Next, a Spring Boot project is initialized and the following Maven dependencies are added: MySQL driver, Lombok, and mybatis-plus-boot-starter (version 3.0.5). It is recommended not to import both MyBatis and MyBatis‑Plus to avoid version conflicts.

<!-- Database driver -->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
</dependency>

<!-- Lombok -->
<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
</dependency>

<!-- MyBatis‑Plus -->
<dependency>
  <groupId>com.baomidou</groupId>
  <artifactId>mybatis-plus-boot-starter</artifactId>
  <version>3.0.5</version>
</dependency>

The application.yml file configures the datasource, driver class, username, and password, and enables MyBatis‑Plus logging:

spring:
  profiles:
    active: dev
  datasource:
    url: jdbc:mysql://localhost:3306/mybatis_plus?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: root

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

The entity class User is annotated with Lombok's @Data, @AllArgsConstructor, and @NoArgsConstructor, and defines fields matching the table columns.

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

A mapper interface extends BaseMapper<User>, providing all CRUD methods out of the box.

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.kwhua.pojo.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper extends BaseMapper<User> { }

Typical CRUD tests are shown: inserting a user (auto‑generating the primary key), updating by ID, selecting by ID, batch selection, and deleting (both physical and logical). The article also demonstrates automatic field filling for gmt_create and gmt_modified using @TableField(fill = FieldFill.INSERT) and a custom MetaObjectHandler implementation.

@Slf4j
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        this.setFieldValByName("gmt_create", new Date(), metaObject);
        this.setFieldValByName("gmt_modified", new Date(), metaObject);
    }
    @Override
    public void updateFill(MetaObject metaObject) {
        this.setFieldValByName("gmt_modified", new Date(), metaObject);
    }
}

Optimistic locking is enabled by adding a version field annotated with @Version and registering OptimisticLockerInterceptor as a bean. The article shows both successful and failed lock scenarios.

@Version
private Integer version;

@Bean
public OptimisticLockerInterceptor optimisticLockerInterceptor() {
    return new OptimisticLockerInterceptor();
}

Pagination is performed with MyBatis‑Plus's Page<User> object, and a pagination interceptor bean is configured.

@Bean
public PaginationInterceptor paginationInterceptor() {
    return new PaginationInterceptor();
}

Page<User> page = new Page<>(2, 5);
userMapper.selectPage(page, null);

Logical deletion is achieved by adding a deleted column, annotating it with @TableLogic, and configuring a LogicSqlInjector bean together with global config values for deleted and not‑deleted states.

@TableLogic
private Integer deleted;

@Bean
public ISqlInjector sqlInjector() {
    return new LogicSqlInjector();
}

A performance interceptor limits SQL execution time (e.g., 100 ms) and formats the output.

@Bean
@Profile({"dev", "test"})
public PerformanceInterceptor performanceInterceptor() {
    PerformanceInterceptor pi = new PerformanceInterceptor();
    pi.setMaxTime(100);
    pi.setFormat(true);
    return pi;
}

The article also covers the use of QueryWrapper for building dynamic queries (e.g., .isNotNull(...).ge(...)) and simple equality checks.

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.isNotNull("name").isNotNull("email").ge("age", 18);
List<User> users = userMapper.selectList(wrapper);

Finally, a code generator example demonstrates how to configure AutoGenerator to produce entity, mapper, service, and controller classes automatically based on database tables.

AutoGenerator mpg = new AutoGenerator();
GlobalConfig gc = new GlobalConfig();
gc.setOutputDir(projectPath + "/src/main/java");
gc.setAuthor("kwhua");
gc.setSwagger2(true);
mpg.setGlobalConfig(gc);

DataSourceConfig dsc = new DataSourceConfig();
dsc.setUrl("jdbc:mysql://localhost:3306/kwhua_test?useSSL=false&serverTimezone=GMT%2B8");
dsc.setDriverName("com.mysql.cj.jdbc.Driver");
dsc.setUsername("root");
dsc.setPassword("root");
mpg.setDataSource(dsc);

PackageConfig pc = new PackageConfig();
pc.setParent("com.kwhua");
pc.setModuleName("model");
mpg.setPackageInfo(pc);

StrategyConfig strategy = new StrategyConfig();
strategy.setInclude("user", "course");
strategy.setNaming(NamingStrategy.underline_to_camel);
strategy.setEntityLombokModel(true);
mpg.setStrategy(strategy);

mpg.execute();

Overall, the article serves as a practical reference for developers integrating MyBatis‑Plus into Spring Boot projects, covering essential configurations, common pitfalls, and advanced features.