文章目录

1. 相关配置和代码
2. 整合原理
- 2.1 spring boot自动配置
- 2.2 MybatisPlusAutoConfiguration
- 2.3 debug流程
- - 2.3.1 MapperScannerRegistrar
  - 2.3.2MapperScannerConfigurer
  - 2.3.3 创建MybatisPlusAutoConfiguration
  - 2.3.4 创建sqlSessionFactory
  - 2.3.5 创建SqlSessionTemplate
  - 2.3.6 mapper接口代理对象创建

1. 相关配置和代码

maven

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.14</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.boge</groupId><artifactId>mybatisplus-spring-boot</artifactId><version>0.0.1-SNAPSHOT</version><name>mybatis-spring-boot</name><description>mybatis-spring-boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.3.1</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.2.18</version></dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter-test</artifactId><version>2.3.1</version><scope>test</scope></dependency><!-- https://mvnrepository.com/artifact/org.projectlombok/lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.28</version><scope>provided</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

application.yml

server:port: 8000
spring:main:allow-circular-references: trueallow-bean-definition-overriding: trueapplication:name: freedom-codedatasource:type: com.alibaba.druid.pool.DruidDataSource# MYSQL 5 驱动：com.mysql.jdbc.Driver，MYSQL 6+ 驱动：com.mysql.cj.jdbc.Driverdriver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/mybatis-vip?characterEncoding=utf-8&serverTimezone=UTCusername: rootpassword: sdfsaxs!druid:# 初始化大小，最小，最大initial-size: 5min-idle: 5max-active: 100# 配置获取连接等待超时的时间max-wait: 60000# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位毫秒time-between-eviction-runs-millis: 60000# 配置一个连接在池中最小生存时间min-evictable-idle-time-millis: 300000validation-query: select VERSION()test-while-idle: truetest-on-borrow: falsetest-on-return: false# mybatisplus的配置
mybatis-plus:configuration:# 是否开启自动驼峰命名规则map-underscore-to-camel-case: true# 对所有的 resultMap 都进行自动映射auto-mapping-behavior: full# #控制台打印完整带参数SQL语句log-impl: org.apache.ibatis.logging.stdout.StdOutImplmapper-locations: classpath:mapper/**/*.xmltype-aliases-package: "com.boge.pojo"

@Mapper
public interface UserMapper extends BaseMapper<UserDO> {List<User> query();
}

@Data
@TableName("t_user")
public class UserDO implements Serializable {@TableId(type = IdType.ASSIGN_ID)private Integer id;private String userName;private String password;private String realName;private Integer age;private Integer dId;}

@MapperScan("com.boge.mapper")
@SpringBootApplication
public class MybatisSpringBootApplication {public static void main(String[] args) {SpringApplication.run(MybatisSpringBootApplication.class, args);}}

2. 整合原理

关注三个对象的创建：

SqlSessionFactory如何创建
SqlSession如何创建
Mapper接口的代理类如何创建（比如UserMapper）。

2.1 spring boot自动配置

在这里插入图片描述

2.2 MybatisPlusAutoConfiguration

源码


/*** {@link EnableAutoConfiguration Auto-Configuration} for Mybatis. Contributes a* {@link SqlSessionFactory} and a {@link SqlSessionTemplate}.* <p>* If {@link org.mybatis.spring.annotation.MapperScan} is used, or a* configuration file is specified as a property, those will be considered,* otherwise this auto-configuration will attempt to register mappers based on* the interface definitions in or under the root auto-configuration package.* </p>* <p> copy from {@link org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration}</p>** @author Eddú Meléndez* @author Josh Long* @author Kazuki Shimizu* @author Eduardo Macarrón*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties(MybatisPlusProperties.class)
@AutoConfigureAfter({DataSourceAutoConfiguration.class, MybatisPlusLanguageDriverAutoConfiguration.class})
public class MybatisPlusAutoConfiguration implements InitializingBean {private static final Logger logger = LoggerFactory.getLogger(MybatisPlusAutoConfiguration.class);private final MybatisPlusProperties properties;private final Interceptor[] interceptors;private final TypeHandler[] typeHandlers;private final LanguageDriver[] languageDrivers;private final ResourceLoader resourceLoader;private final DatabaseIdProvider databaseIdProvider;private final List<ConfigurationCustomizer> configurationCustomizers;private final List<SqlSessionFactoryBeanCustomizer> sqlSessionFactoryBeanCustomizers;private final List<MybatisPlusPropertiesCustomizer> mybatisPlusPropertiesCustomizers;private final ApplicationContext applicationContext;public MybatisPlusAutoConfiguration(MybatisPlusProperties properties,ObjectProvider<Interceptor[]> interceptorsProvider,ObjectProvider<TypeHandler[]> typeHandlersProvider,ObjectProvider<LanguageDriver[]> languageDriversProvider,ResourceLoader resourceLoader,ObjectProvider<DatabaseIdProvider> databaseIdProvider,ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider,ObjectProvider<List<SqlSessionFactoryBeanCustomizer>> sqlSessionFactoryBeanCustomizers,ObjectProvider<List<MybatisPlusPropertiesCustomizer>> mybatisPlusPropertiesCustomizerProvider,ApplicationContext applicationContext) {this.properties = properties;this.interceptors = interceptorsProvider.getIfAvailable();this.typeHandlers = typeHandlersProvider.getIfAvailable();this.languageDrivers = languageDriversProvider.getIfAvailable();this.resourceLoader = resourceLoader;this.databaseIdProvider = databaseIdProvider.getIfAvailable();this.configurationCustomizers = configurationCustomizersProvider.getIfAvailable();this.sqlSessionFactoryBeanCustomizers = sqlSessionFactoryBeanCustomizers.getIfAvailable();this.mybatisPlusPropertiesCustomizers = mybatisPlusPropertiesCustomizerProvider.getIfAvailable();this.applicationContext = applicationContext;}@Overridepublic void afterPropertiesSet() {if (!CollectionUtils.isEmpty(mybatisPlusPropertiesCustomizers)) {mybatisPlusPropertiesCustomizers.forEach(i -> i.customize(properties));}checkConfigFileExists();}private 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 {// TODO 使用 MybatisSqlSessionFactoryBean 而不是 SqlSessionFactoryBeanMybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();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());}// TODO 修改源码支持定义 TransactionFactorythis.getBeanThen(TransactionFactory.class, factory::setTransactionFactory);// TODO 对源码做了一定的修改(因为源码适配了老旧的mybatis版本,但我们不需要适配)Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();if (!ObjectUtils.isEmpty(this.languageDrivers)) {factory.setScriptingLanguageDrivers(this.languageDrivers);}Optional.ofNullable(defaultLanguageDriver).ifPresent(factory::setDefaultScriptingLanguageDriver);applySqlSessionFactoryBeanCustomizers(factory);// TODO 此处必为非 NULLGlobalConfig globalConfig = this.properties.getGlobalConfig();// TODO 注入填充器this.getBeanThen(MetaObjectHandler.class, globalConfig::setMetaObjectHandler);// TODO 注入参与器this.getBeanThen(PostInitTableInfoHandler.class, globalConfig::setPostInitTableInfoHandler);// TODO 注入主键生成器this.getBeansThen(IKeyGenerator.class, i -> globalConfig.getDbConfig().setKeyGenerators(i));// TODO 注入sql注入器this.getBeanThen(ISqlInjector.class, globalConfig::setSqlInjector);// TODO 注入ID生成器this.getBeanThen(IdentifierGenerator.class, globalConfig::setIdentifierGenerator);// TODO 设置 GlobalConfig 到 MybatisSqlSessionFactoryBeanfactory.setGlobalConfig(globalConfig);return factory.getObject();}/*** 检查spring容器里是否有对应的bean,有则进行消费** @param clazz    class* @param consumer 消费* @param <T>      泛型*/private <T> void getBeanThen(Class<T> clazz, Consumer<T> consumer) {if (this.applicationContext.getBeanNamesForType(clazz, false, false).length > 0) {consumer.accept(this.applicationContext.getBean(clazz));}}/*** 检查spring容器里是否有对应的bean,有则进行消费** @param clazz    class* @param consumer 消费* @param <T>      泛型*/private <T> void getBeansThen(Class<T> clazz, Consumer<List<T>> consumer) {if (this.applicationContext.getBeanNamesForType(clazz, false, false).length > 0) {final Map<String, T> beansOfType = this.applicationContext.getBeansOfType(clazz);List<T> clazzList = new ArrayList<>();beansOfType.forEach((k, v) -> clazzList.add(v));consumer.accept(clazzList);}}// TODO 入参使用 MybatisSqlSessionFactoryBeanprivate void applyConfiguration(MybatisSqlSessionFactoryBean factory) {// TODO 使用 MybatisConfigurationMybatisConfiguration configuration = this.properties.getConfiguration();if (configuration == null && !StringUtils.hasText(this.properties.getConfigLocation())) {configuration = new MybatisConfiguration();}if (configuration != null && !CollectionUtils.isEmpty(this.configurationCustomizers)) {for (ConfigurationCustomizer customizer : this.configurationCustomizers) {customizer.customize(configuration);}}factory.setConfiguration(configuration);}private void applySqlSessionFactoryBeanCustomizers(MybatisSqlSessionFactoryBean factory) {if (!CollectionUtils.isEmpty(this.sqlSessionFactoryBeanCustomizers)) {for (SqlSessionFactoryBeanCustomizer customizer : this.sqlSessionFactoryBeanCustomizers) {customizer.customize(factory);}}}@Bean@ConditionalOnMissingBeanpublic SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {ExecutorType executorType = this.properties.getExecutorType();if (executorType != null) {return new SqlSessionTemplate(sqlSessionFactory, executorType);} else {return new SqlSessionTemplate(sqlSessionFactory);}}/*** This will just scan the same base package as Spring Boot does. If you want more power, you can explicitly use* {@link org.mybatis.spring.annotation.MapperScan} but this will get typed mappers working correctly, out-of-the-box,* similar to using Spring Data JPA repositories.*/public static class AutoConfiguredMapperScannerRegistrarimplements BeanFactoryAware, EnvironmentAware, ImportBeanDefinitionRegistrar {private BeanFactory beanFactory;private Environment environment;@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");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+// TODO 兼容了mybatis.lazy-initialization配置builder.addPropertyValue("lazyInitialization", "${mybatis-plus.lazy-initialization:${mybatis.lazy-initialization:false}}");}if (propertyNames.contains("defaultScope")) {// Need to mybatis-spring 2.0.6+builder.addPropertyValue("defaultScope", "${mybatis-plus.mapper-default-scope:}");}// for spring-nativeboolean injectSqlSession = environment.getProperty("mybatis.inject-sql-session-on-mapper-scan", Boolean.class,Boolean.TRUE);if (injectSqlSession && this.beanFactory instanceof ListableBeanFactory) {ListableBeanFactory listableBeanFactory = (ListableBeanFactory) this.beanFactory;Optional<String> sqlSessionTemplateBeanName = Optional.ofNullable(getBeanNameForType(SqlSessionTemplate.class, listableBeanFactory));Optional<String> sqlSessionFactoryBeanName = Optional.ofNullable(getBeanNameForType(SqlSessionFactory.class, listableBeanFactory));if (sqlSessionTemplateBeanName.isPresent() || !sqlSessionFactoryBeanName.isPresent()) {builder.addPropertyValue("sqlSessionTemplateBeanName",sqlSessionTemplateBeanName.orElse("sqlSessionTemplate"));} else {builder.addPropertyValue("sqlSessionFactoryBeanName", sqlSessionFactoryBeanName.get());}}builder.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());}@Overridepublic void setBeanFactory(BeanFactory beanFactory) {this.beanFactory = beanFactory;}@Overridepublic void setEnvironment(Environment environment) {this.environment = environment;}private String getBeanNameForType(Class<?> type, ListableBeanFactory factory) {String[] beanNames = factory.getBeanNamesForType(type);return beanNames.length > 0 ? beanNames[0] : null;}}/*** If mapper registering configuration or mapper scanning configuration not present, this configuration allow to scan* mappers based on the same component-scanning path as Spring Boot itself.*/@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.");}}@Order@Bean@ConditionalOnMissingBeanpublic DdlApplicationRunner ddlApplicationRunner(@Autowired(required = false) List<IDdl> ddlList) {if (ObjectUtils.isEmpty(ddlList)) {return null;}return new DdlApplicationRunner(ddlList);}
}