引入依赖

<dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.4</version>
</dependency>

@ConditionalOnSingleCandidate(DataSource.class)

单一数据源

 SqlSessionFactory: 自动配置好了

  @Bean@ConditionalOnMissingBeanpublic SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {SqlSessionFactoryBean factory = new SqlSessionFactoryBean();factory.setDataSource(dataSource);factory.setVfs(SpringBootVFS.class);//xxxxxxxxxxx
}

DataSource dataSource
factory.setDataSource(dataSource);

数据源

  @Bean@ConditionalOnMissingBeanpublic SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {ExecutorType executorType = this.properties.getExecutorType();if (executorType != null) {return new SqlSessionTemplate(sqlSessionFactory, executorType);} else {return new SqlSessionTemplate(sqlSessionFactory);}}

 SqlSession：自动配置了 SqlSessionTemplate 组合了SqlSession

  @org.springframework.context.annotation.Configuration@Import(AutoConfiguredMapperScannerRegistrar.class)@ConditionalOnMissingBean({ MapperFactoryBean.class, MapperScannerConfigurer.class })public static class MapperScannerRegistrarNotFoundConfiguration implements InitializingBean {@Overridepublic void afterPropertiesSet() {logger.debug("Not found configuration for registering mapper bean using @MapperScan, MapperFactoryBean and MapperScannerConfigurer.");}}

 @Import(AutoConfiguredMapperScannerRegistrar.class）；

public static class AutoConfiguredMapperScannerRegistrar implements BeanFactoryAware, ImportBeanDefinitionRegistrar {private BeanFactory beanFactory;@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {if (!AutoConfigurationPackages.has(this.beanFactory)) {logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.");return;}logger.debug("Searching for mappers annotated with @Mapper");//xxxxxxxxxxxxx}}

AnnotationMetadata（注解）

logger.debug("Searching for mappers annotated with @Mapper");

找到所有带有@Mapper的接口

• Mapper： 只要我们写的操作MyBatis的接口标注了 @Mapper 就会被自动扫描进来

classpath:

classpath类路径在 Spring Boot 中既指程序在打包前的/java/目录加上/resource目录，也指程序在打包后生成的/classes/目录。两者实际上指的是同一个目录，里面包含的文件内容一模一样。