spring为mapper生成一个单例FactoryBean_spring.mapper.mapperfactorybean-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_19457117/article/details/90045913

本文详细解析了MyBatis Spring中ClassPathMapperScanner如何扫描Mapper接口，并将其转换为MapperFactoryBean，设置必要的属性如SqlSessionFactory或SqlSessionTemplate，最终生成Mapper代理类。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

class: org.mybatis.spring.mapper.ClassPathMapperScanner

private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
  // beanDefinitions 就是扫描出来的Mapper接口bean定义
    GenericBeanDefinition definition;
    for (BeanDefinitionHolder holder : beanDefinitions) {
      definition = (GenericBeanDefinition) holder.getBeanDefinition();
      String beanClassName = definition.getBeanClassName();
      LOGGER.debug(() -> "Creating MapperFactoryBean with name '" + holder.getBeanName()
          + "' and '" + beanClassName + "' mapperInterface");

      // the mapper interface is the original class of the bean
      // but, the actual class of the bean is MapperFactoryBean
      // 构造函数参数就是接口类
      definition.getConstructorArgumentValues().addGenericArgumentValue(beanClassName); // issue #59
      // 偷梁换柱, 变成mapperFactoryBean
      definition.setBeanClass(this.mapperFactoryBeanClass);
	  
	  // 设置属性
      definition.getPropertyValues().add("addToConfig", this.addToConfig);

      boolean explicitFactoryUsed = false;
      if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) {
        definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName));
        explicitFactoryUsed = true;
      } else if (this.sqlSessionFactory != null) {
        definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory);
        explicitFactoryUsed = true;
      }

      if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) {
        if (explicitFactoryUsed) {
          LOGGER.warn(() -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
        }
        definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName));
        explicitFactoryUsed = true;
      } else if (this.sqlSessionTemplate != null) {
        if (explicitFactoryUsed) {
          LOGGER.warn(() -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
        }
        definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate);
        explicitFactoryUsed = true;
      }

      if (!explicitFactoryUsed) {
        LOGGER.debug(() -> "Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'.");
        definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
      }
    }
  }

class: org.mybatis.spring.mapper.MapperFactoryBean

/**
   * {@inheritDoc}
   */
  @Override
  public T getObject() throws Exception {
    // 通过FactoryBean为Mapper创建了一个代理类, spring发现是个FactoryBean回去调用这个方法,从而创建出真正的Mapper代理类MapperProxy
    return getSqlSession().getMapper(this.mapperInterface);
  }