基于Spring整合mybatis的mapper生成過程

更新時間：2023年03月07日 15:09:16 作者：asLightYouAre

這篇文章主要介紹了Spring整合mybatis的mapper生成過程，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

Spring整合mybatis的mapper生成過程

mapperScannerConfigurer實現(xiàn)了BeandifinitionRegistryPostProcessor

后置處理beanFactory時會調(diào)用其postProcessBeanDefinitionRegistry

public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
    if (this.processPropertyPlaceHolders) {
      processPropertyPlaceHolders();
    }
 
    ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
    scanner.setAddToConfig(this.addToConfig);
    scanner.setAnnotationClass(this.annotationClass);
    scanner.setMarkerInterface(this.markerInterface);
    scanner.setSqlSessionFactory(this.sqlSessionFactory);
    scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
    scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
    scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
    scanner.setResourceLoader(this.applicationContext);
    scanner.setBeanNameGenerator(this.nameGenerator);
    scanner.setMapperFactoryBeanClass(this.mapperFactoryBeanClass);
    scanner.registerFilters();
//掃描包集合，注冊mapper的beandifinition
    scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
  }

ClassPathMapperScanner#doScan

public Set<BeanDefinitionHolder> doScan(String... basePackages) {
    Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
 
    if (beanDefinitions.isEmpty()) {
      LOGGER.warn(() -> "No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration.");
    } else {
//會對bean信息進行一些更改和添加，如設置propertyValues，向其中添加sqlsessionFactory等屬性信息等
      processBeanDefinitions(beanDefinitions);
    }
 
    return beanDefinitions;
  }

ClassPathBeanDefinitionScanner#doScan

protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
		Assert.notEmpty(basePackages, "At least one base package must be specified");
		Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
		for (String basePackage : basePackages) {
//遍歷集合掃描包，獲取包下的可用的mapper信息
			Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
			for (BeanDefinition candidate : candidates) {
				ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
				candidate.setScope(scopeMetadata.getScopeName());
				String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
				if (candidate instanceof AbstractBeanDefinition) {
					postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
				}
				if (candidate instanceof AnnotatedBeanDefinition) {
					AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
				}
				if (checkCandidate(beanName, candidate)) {
					BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
					definitionHolder =
							AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
					beanDefinitions.add(definitionHolder);
					registerBeanDefinition(definitionHolder, this.registry);
				}
			}
		}
		return beanDefinitions;
	}

如上在進行包掃描時，會調(diào)用ClassPathBeanDefinitionScanner#doScan，進行beanDefinition的掃描和注冊

執(zhí)行完后調(diào)用ClassPathMapperScanner#processBeanDefinitions

private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
//有省略部分
       
    //這里有遍歷所有mapper
//將所有mapper的beanClass改為了mapperFactoryBean，最后生成的bean也是該類型的，只有在用到的
//時候才會調(diào)用getObject生成mapper
      definition.setBeanClass(this.mapperFactoryBeanClass);
//接下來是添加一些MapperFactoryBean的屬性信息到beandefinition里，在生成實例的時候，會根據(jù)
//此處傳入的值來進行具體設置，如sqlsessionFactory
      definition.getPropertyValues().add("addToConfig", this.addToConfig);
 
      
      if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) {
        definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName));
      
      } else if (this.sqlSessionFactory != null) {
        definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory);
        
      }
 
      if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) {
        
        definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName));
        
      } else if (this.sqlSessionTemplate != null) {
        
        definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate);
        
      }
  }

確定了所有的mapper的beanDefinition為MapperFactoryBean類型后，

確定在生成的bean皆為MapperFactoryBean，在getBean時會調(diào)用MapperFactoryBean#getObject