MyBatis 之 Spring-boot 自动配置

spring.factories

在依赖包 mybatis-spring-boot-autoconfigure-2.2.0.jar 中找到 spring.factories。

可以看到，主要的自动配置类为：MybatisAutoConfiguration

properties

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.mybatis.spring.boot.autoconfigure.MybatisLanguageDriverAutoConfiguration,\
org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration

MybatisAutoConfiguration

主要两点：

实例化 SqlSessionFactory 时，扫描 mapper.xml 并建立映射关系。
用 MapperScannerConfigurer 扫描 @Mapper 并在 MyBatis 中生成代理对象，然后注册到 Spring 容器。

实例化 bean SqlSessionFactory，并初始化部分默认参数，并解析并建立各种 Mapper 接口对应的 .xml SQL 文件的映射关系。
实例化 bean SqlSessionTemplate，实际上就是 SqlSession 对象。
导入了这个类 AutoConfiguredMapperScannerRegistrar，用来扫描 @Mapper 注解
AutoConfiguredMapperScannerRegistrar implements BeanFactoryAware, ImportBeanDefinitionRegistrar
在 AutoConfiguredMapperScannerRegistrar 这个类中注册了 BeanDefinition MapperScannerConfigurer.java
于是，主要的工作就由 MapperScannerConfigurer 类来完成。

java

@org.springframework.context.annotation.Configuration
@ConditionalOnClass({ SqlSessionFactory.class, SqlSessionFactoryBean.class })
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties(MybatisProperties.class)
@AutoConfigureAfter({ DataSourceAutoConfiguration.class, MybatisLanguageDriverAutoConfiguration.class })
public class MybatisAutoConfiguration implements InitializingBean {
    @Bean
    @ConditionalOnMissingBean
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
        factory.setDataSource(dataSource);
        factory.setVfs(SpringBootVFS.class);
        if (StringUtils.hasText(this.properties.getConfigLocation())) {
            factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));
        }
        applyConfiguration(factory);
        if (this.properties.getConfigurationProperties() != null) {
            factory.setConfigurationProperties(this.properties.getConfigurationProperties());
        }
        if (!ObjectUtils.isEmpty(this.interceptors)) {
            factory.setPlugins(this.interceptors);
        }
        if (this.databaseIdProvider != null) {
            factory.setDatabaseIdProvider(this.databaseIdProvider);
        }
        if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {
            factory.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());
        }
        if (this.properties.getTypeAliasesSuperType() != null) {
            factory.setTypeAliasesSuperType(this.properties.getTypeAliasesSuperType());
        }
        if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {
            factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());
        }
        if (!ObjectUtils.isEmpty(this.typeHandlers)) {
            factory.setTypeHandlers(this.typeHandlers);
        }
        if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {
            factory.setMapperLocations(this.properties.resolveMapperLocations());
        }
        Set<String> factoryPropertyNames = Stream
                .of(new BeanWrapperImpl(SqlSessionFactoryBean.class).getPropertyDescriptors()).map(PropertyDescriptor::getName)
                .collect(Collectors.toSet());
        Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();
        if (factoryPropertyNames.contains("scriptingLanguageDrivers") && !ObjectUtils.isEmpty(this.languageDrivers)) {
            // Need to mybatis-spring 2.0.2+
            factory.setScriptingLanguageDrivers(this.languageDrivers);
            if (defaultLanguageDriver == null && this.languageDrivers.length == 1) {
                defaultLanguageDriver = this.languageDrivers[0].getClass();
            }
        }
        if (factoryPropertyNames.contains("defaultScriptingLanguageDriver")) {
            // Need to mybatis-spring 2.0.2+
            factory.setDefaultScriptingLanguageDriver(defaultLanguageDriver);
        }

        return factory.getObject();
    }

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

    public static class AutoConfiguredMapperScannerRegistrar implements BeanFactoryAware, ImportBeanDefinitionRegistrar {

        private BeanFactory beanFactory;

        @Override
        public 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");

            List<String> packages = AutoConfigurationPackages.get(this.beanFactory);
            if (logger.isDebugEnabled()) {
                packages.forEach(pkg -> logger.debug("Using auto-configuration base package '{}'", pkg));
            }

            BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);
            builder.addPropertyValue("processPropertyPlaceHolders", true);
            builder.addPropertyValue("annotationClass", Mapper.class);
            builder.addPropertyValue("basePackage", StringUtils.collectionToCommaDelimitedString(packages));
            BeanWrapper beanWrapper = new BeanWrapperImpl(MapperScannerConfigurer.class);
            Set<String> propertyNames = Stream.of(beanWrapper.getPropertyDescriptors()).map(PropertyDescriptor::getName)
                    .collect(Collectors.toSet());
            if (propertyNames.contains("lazyInitialization")) {
                // Need to mybatis-spring 2.0.2+
                builder.addPropertyValue("lazyInitialization", "${mybatis.lazy-initialization:false}");
            }
            if (propertyNames.contains("defaultScope")) {
                // Need to mybatis-spring 2.0.6+
                builder.addPropertyValue("defaultScope", "${mybatis.mapper-default-scope:}");
            }
            registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());
        }

        @Override
        public void setBeanFactory(BeanFactory beanFactory) {
            this.beanFactory = beanFactory;
        }
    }

    /**
     * 导入了这个类 AutoConfiguredMapperScannerRegistrar
     * 用来扫描 @Mapper 注解，最后在 Spring 实例化 bean 的时候，利用 MapperFactoryBean.getObject() 来获取 MyBatis 中 SqlSession 生成的各种 Mapper 接口的代理对象。
     */
    @org.springframework.context.annotation.Configuration
    @Import(AutoConfiguredMapperScannerRegistrar.class)
    @ConditionalOnMissingBean({ MapperFactoryBean.class, MapperScannerConfigurer.class })
    public static class MapperScannerRegistrarNotFoundConfiguration implements InitializingBean {

        @Override
        public void afterPropertiesSet() {
            logger.debug(
                    "Not found configuration for registering mapper bean using @MapperScan, MapperFactoryBean and MapperScannerConfigurer.");
        }
    }
}

MyBatis 之 Spring-boot 自动配置 ​

spring.factories ​

MybatisAutoConfiguration ​

MyBatis 之 Spring-boot 自动配置

spring.factories

MybatisAutoConfiguration