可以看到Mybatis初始化所需要的很多属性都在这里，相当于一个JavaBean 。
下面重点看一下MybatisAutoConfiguration的代码：
@org.springframework.context.annotation.Configuration@ConditionalOnClass({ SqlSessionFactory.class, SqlSessionFactoryBean.class })@ConditionalOnBean(DataSource.class)@EnableConfigurationProperties(MybatisProperties.class)@AutoConfigureAfter(DataSourceAutoConfiguration.class)public class MybatisAutoConfiguration {private static final Logger logger = LoggerFactory.getLogger(MybatisAutoConfiguration.class);private final MybatisProperties properties;private final Interceptor[] interceptors;private final ResourceLoader resourceLoader;private final DatabaseIdProvider databaseIdProvider;private final List<ConfigurationCustomizer> configurationCustomizers;public MybatisAutoConfiguration(MybatisProperties properties,ObjectProvider<Interceptor[]> interceptorsProvider,ResourceLoader resourceLoader,ObjectProvider<DatabaseIdProvider> databaseIdProvider,ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider) {this.properties = properties;this.interceptors = interceptorsProvider.getIfAvailable();this.resourceLoader = resourceLoader;this.databaseIdProvider = databaseIdProvider.getIfAvailable();this.configurationCustomizers = configurationCustomizersProvider.getIfAvailable();}@PostConstructpublic void checkConfigFileExists() {if (this.properties.isCheckConfigLocation() && StringUtils.hasText(this.properties.getConfigLocation())) {Resource resource = this.resourceLoader.getResource(this.properties.getConfigLocation());Assert.state(resource.exists(), "Cannot find config location: " + resource+ " (please add config file or check your Mybatis configuration)");}}@Bean@ConditionalOnMissingBeanpublic 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()));}Configuration configuration = this.properties.getConfiguration();if (configuration == null && !StringUtils.hasText(this.properties.getConfigLocation())) {configuration = new Configuration();}if (configuration != null && !CollectionUtils.isEmpty(this.configurationCustomizers)) {for (ConfigurationCustomizer customizer : this.configurationCustomizers) {customizer.customize(configuration);}}factory.setConfiguration(configuration);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 (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());}if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {factory.setMapperLocations(this.properties.resolveMapperLocations());}return factory.getObject();}@Bean@ConditionalOnMissingBeanpublic 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 AutoConfiguredMapperScannerRegistrarimplements BeanFactoryAware, ImportBeanDefinitionRegistrar, ResourceLoaderAware {private BeanFactory beanFactory;private ResourceLoader resourceLoader;@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);try {if (this.resourceLoader != null) {scanner.setResourceLoader(this.resourceLoader);}List<String> packages = AutoConfigurationPackages.get(this.beanFactory);if (logger.isDebugEnabled()) {for (String pkg : packages) {logger.debug("Using auto-configuration base package '{}'", pkg);}}scanner.setAnnotationClass(Mapper.class);scanner.registerFilters();scanner.doScan(StringUtils.toStringArray(packages));} catch (IllegalStateException ex) {logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.", ex);}}@Overridepublic void setBeanFactory(BeanFactory beanFactory) throws BeansException {this.beanFactory = beanFactory;}@Overridepublic void setResourceLoader(ResourceLoader resourceLoader) {this.resourceLoader = resourceLoader;}}@org.springframework.context.annotation.Configuration@Import({ AutoConfiguredMapperScannerRegistrar.class })@ConditionalOnMissingBean(MapperFactoryBean.class)public static class MapperScannerRegistrarNotFoundConfiguration {@PostConstructpublic void afterPropertiesSet() {logger.debug("No {} found.", MapperFactoryBean.class.getName());}}}