MapperScannerConfigurer 做用详解

自动扫描 将Mapper接口生成代理注入到Spring

<!-- DAO接口所在包名，Spring会自动查找其下的类 -->
	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.em" />
		<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
	</bean>

• MapperFactoryBean 建立的代理类实现了 UserMapper 接口,而且注入到应用程序中
• 把Mapper接口转换成MapperFactoryBean
  • 其实在SqlSessionFactoryBean 里面就已经实现了注册了 MapperProxyFactory 到Mybatis
  • 这里作的是把它们托管到spring

{
    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.registerFilters();
    scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
  }

• 注意，无论前后顺序

  • SqlSessionFactoryBean 继承了InitializingBean 接口

    • 会在全部spring 注册完成后，执行afterPropertiesSet方法

    • public void afterPropertiesSet() throws Exception {
          Assert.notNull(this.dataSource, "Property 'dataSource' is required");
          Assert.notNull(this.sqlSessionFactoryBuilder, "Property 'sqlSessionFactoryBuilder' is required");
          this.sqlSessionFactory = this.buildSqlSessionFactory();
      }