[Java知识库]MyBatis-Plus和SpringBoot的整合

简介

MyBatis-Plus是一个 MyBatis (opens new window)的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

一、MyBatis-Plus和SpringBoot整合应用

1.1 项目依赖

在原项目依赖上，加上下面依赖

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3</version>
</dependency>

1.2 项目配置

使用mybatis-plus-boot-starter后，spring将扫描所有标准@Mapper的类（不需要使用@MapperScan），所以我们直接使用mybatis-plus的功能，不需要手动配置SqlSessionTemplate，MybatisSqlSessionFactoryBean，dataSource，因为MyBatis-Spring-Boot-Starter帮我们配置好了。

mybatis-plus-boot-starter在其spring.factories文件中配置2个配置类，mybatis-plus主要配置都在MybatisPlusAutoConfiguration中

org.springframework.boot.env.EnvironmentPostProcessor=\
  com.baomidou.mybatisplus.autoconfigure.SafetyEncryptProcessor
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.baomidou.mybatisplus.autoconfigure.IdentifierGeneratorAutoConfiguration,\
  com.baomidou.mybatisplus.autoconfigure.MybatisPlusLanguageDriverAutoConfiguration,\
  com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration

二、Mybatis和Spring整合源码分析

其数据源配置和事务都已经配置好了，一般情况下不用我们自己配置

以下代码都在MybatisPlusAutoConfiguration中

2.1 SqlSessionFactory的注册

@Configuration
@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<MybatisPlusPropertiesCustomizer> mybatisPlusPropertiesCustomizers;

    private final ApplicationContext applicationContext;

    //构造器注入
    public MybatisPlusAutoConfiguration(MybatisPlusProperties properties,
                                        ObjectProvider<Interceptor[]> interceptorsProvider,
                                        ObjectProvider<TypeHandler[]> typeHandlersProvider,
                                        ObjectProvider<LanguageDriver[]> languageDriversProvider,
                                        ResourceLoader resourceLoader,
                                        ObjectProvider<DatabaseIdProvider> databaseIdProvider,
                                        ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider,
                                        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.mybatisPlusPropertiesCustomizers = mybatisPlusPropertiesCustomizerProvider.getIfAvailable();
        this.applicationContext = applicationContext;
    }

    @SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")
    @Bean
    @ConditionalOnMissingBean
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        // TODO 使用 MybatisSqlSessionFactoryBean 而不是 SqlSessionFactoryBean
        MybatisSqlSessionFactoryBean 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());
        }
        //插件
        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);
        }
        Resource[] mapperLocations = this.properties.resolveMapperLocations();
        if (!ObjectUtils.isEmpty(mapperLocations)) {
            factory.setMapperLocations(mapperLocations);
        }
        // TODO 修改源码支持定义 TransactionFactory
        this.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);

        // TODO 自定义枚举包
        //获取配置文件
        if (StringUtils.hasLength(this.properties.getTypeEnumsPackage())) {
            factory.setTypeEnumsPackage(this.properties.getTypeEnumsPackage());
        }
        // TODO 此处必为非 NULL
        //获取配置文件
        GlobalConfig globalConfig = this.properties.getGlobalConfig();
        // TODO 注入填充器 //从容器中找MetaObjectHandler
        this.getBeanThen(MetaObjectHandler.class, globalConfig::setMetaObjectHandler);
        // TODO 注入主键生成器 //从容器中找IKeyGenerator
        this.getBeansThen(IKeyGenerator.class, i -> globalConfig.getDbConfig().setKeyGenerators(i));
        // TODO 注入sql注入器 //从容器中找ISqlInjector
        this.getBeanThen(ISqlInjector.class, globalConfig::setSqlInjector);
        // TODO 注入ID生成器 //从容器中找IdentifierGenerator
        this.getBeanThen(IdentifierGenerator.class, globalConfig::setIdentifierGenerator);
        // TODO 设置 GlobalConfig 到 MybatisSqlSessionFactoryBean
        factory.setGlobalConfig(globalConfig);
        return factory.getObject();
}

1、springBoot通过构造器主人会在容器中寻找Interceptor，所以我们可以用以下方式开启分页功能，这和其与springMVC整合有点不同

@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
    MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
    interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
    return interceptor;
}

2、springBoot会在容器中寻找MetaObjectHandler类型注入GlobalConfig，所以元对象字段填充控制器对象我们可以交给spring管理，这和其与springMVC整合有点不同

IKeyGenerator,ISqlInjector,IdentifierGenerator 也一样

@Bean
public MyMetaObjectHandler metaObjectHandler() {
    return new MyMetaObjectHandler();
}

3、通用枚举，我们通过配置文件指定

mybatis-plus:
    # 支持统配符 * 或者 ; 分割
    typeEnumsPackage: com.baomidou.springboot.entity.enums

4、MyBatis-Plus数据库相关配置，我们通过配置文件指定

mybatis-plus:
  global-config:
    db-config:
      insert-strategy: not_null
      update-strategy: not_null
      select-strategy: not_null
      #  主键类型:
      #  AUTO(0),数据库ID自增
      #  NONE(1),未设置主键类型
      #  INPUT(2),用户输入ID
      #  ASSIGN_ID(3),全局唯一ID (数字类型唯一ID)
      #  ASSIGN_UUID(4),全局唯一ID UUID
      id-type: INPUT
      #  是否开启大写命名，默认不开启
      capital-mode: false
      logic-delete-field: deleteFlag
      logic-delete-value: 1
      logic-not-delete-value: 0

2.2 SqlSessionTemplate的注册

@Configuration
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties(MybatisPlusProperties.class)
@AutoConfigureAfter({DataSourceAutoConfiguration.class, MybatisPlusLanguageDriverAutoConfiguration.class})
public class MybatisPlusAutoConfiguration implements InitializingBean {
    @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);
        }
    }
}

与MyBatis和SpringBoot整合的一样

2.3 扫描映射器类

@Configuration
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties(MybatisPlusProperties.class)
@AutoConfigureAfter({DataSourceAutoConfiguration.class, MybatisPlusLanguageDriverAutoConfiguration.class})
public class MybatisPlusAutoConfiguration implements InitializingBean {
  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+
                // 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:}");
            }
            registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());
        }

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

    /**
     * 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.
     */
    @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.");
        }
    }
}

与MyBatis和SpringBoot整合的一样