How MyBatis Auto-Configuration Works in Spring Boot 3

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This text explains the automatic configuration process in MyBatis-Plus, focusing on mapper registration and SQL statement registration. It describes the steps involved, starting with the registration of SqlSessionFactory and SqlSessionTemplate, followed by the MapperScannerConfigurer that scans for mappers using an annotation. The process involves ClassPathMapperScanner, which overrides the doScan method to wrap scanned mappers into a proxy. The text further explores when SQL statements are registered, detailing how XML configurations are loaded based on the naming convention of mapper files. Overall, it provides insight into how mappers and SQL are seamlessly integrated into the Spring container.

How MyBatis Auto-Configuration Works in Spring Boot 3

Baseline: Spring Boot 3.x, MyBatis Spring Boot Starter 3.x, MyBatis 3.5.x, and Java 17+. Boot 2's javax dependencies cannot be mixed with Boot 3's jakarta dependencies.

1. The Starter's Role

TEXT

DataSource -> SqlSessionFactory -> SqlSessionTemplate -> Mapper 代理

Auto-configuration determines whether to create objects based on the classpath, existing beans, and configuration properties. For the current entry point, use the AutoConfiguration.imports file in the dependency package, configuration metadata, and condition evaluation reports as the source of truth; don't rely on the legacy spring.factories.

2. Minimal Configuration

YAML

mybatis:
  mapper-locations: classpath:/mapper/**/*.xml
  type-aliases-package: com.example.order.domain
  configuration:
    map-underscore-to-camel-case: true
    default-statement-timeout: 5

JAVA

@Mapper
public interface OrderMapper {
    Order findById(long id);
}

3. Bean Creation Chain

Spring Boot creates the DataSource; MyBatis creates the SqlSessionFactory, loads XML mappers, type handlers, and plugins, and creates the SqlSessionTemplate. The mapper scanner registers the MapperFactoryBean; ultimately, it returns a mapper proxy.

Put @Transactional in the service layer. With multiple data sources, explicitly configure each SqlSessionFactory, the mapper scan scope, and the transaction manager. Use #{} parameter binding; ${} performs string concatenation and may only be used with allowlisted fields.

How MyBatis Auto-Configuration Works in Spring Boot 3

Baseline: Spring Boot 3.x, MyBatis Spring Boot Starter 3.x, MyBatis 3.5.x, and Java 17+. Boot 2's javax dependencies cannot be mixed with Boot 3's jakarta dependencies.

1. The Starter's Role

TEXT

DataSource -> SqlSessionFactory -> SqlSessionTemplate -> Mapper 代理

2. Minimal Configuration

YAML

mybatis:
  mapper-locations: classpath:/mapper/**/*.xml
  type-aliases-package: com.example.order.domain
  configuration:
    map-underscore-to-camel-case: true
    default-statement-timeout: 5

JAVA

@Mapper
public interface OrderMapper {
    Order findById(long id);
}