上一篇提到了和Spring整合後，Mybatis的BatchExecutor無法真正生效，本篇就好好分析分析這裡面的原因

　　一配置檔案

<!-- 配置sqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 例項化sqlSessionFactory時需要使用上述配置好的資料來源以及SQL對映檔案 -->
        <property name="dataSource" ref="dataSource" />
        <!-- 自動掃描me/gacl/mapping/目錄下的所有SQL對映的xml檔案, 省掉Configuration.xml裡的手工配置
        value
 
="classpath:me/gacl/mapping/*.xml"指的是classpath(類路徑)下me.gacl.mapping包中的所有xml檔案
        UserMapper.xml位於me.gacl.mapping包下，這樣UserMapper.xml就可以被自動掃描
         -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath:me/gacl/mapping/*.xml" />
    </bean>

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 掃描me.gacl.dao這個包以及它的子包下的所有對映介面類 -->
        <property name="basePackage" value="me.gacl.dao" />
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
    </bean>

　　接下來我們就好好分析這兩個類SqlSessionFactoryBean ，MapperScannerConfigurer

　　二SqlSessionFactoryBean

public class SqlSessionFactoryBean implements FactoryBean<SqlSessionFactory>, InitializingBean, ApplicationListener<ApplicationEvent> {

　　它是一個FactoryBean，那我們只需要關注getObject方法就好了

@Override
  public SqlSessionFactory getObject() throws Exception {
    if (this.sqlSessionFactory == null) {
      afterPropertiesSet();
    }

    return this.sqlSessionFactory;
  }

　　這樣，spring容器內就有一個java bean，name是我們配的sqlSessionFactory

　　三MapperScannerConfigurer

　　它實現了介面BeanDefinitionRegistryPostProcessor 就說明它具有想beanFactory註冊BeanDefinition的能力

public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware

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

　　因為我們只配了<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" /> 所以這裡 this.sqlSessionFactory = null

　　basePackage =me.gacl.dao

　　直接跳到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 {
      for (BeanDefinitionHolder holder : beanDefinitions) {
        GenericBeanDefinition definition = (GenericBeanDefinition) holder.getBeanDefinition();

        if (logger.isDebugEnabled()) {
          logger.debug("Creating MapperFactoryBean with name '" + holder.getBeanName() 
              + "' and '" + definition.getBeanClassName() + "' mapperInterface");
        }

        // the mapper interface is the original class of the bean
        // but, the actual class of the bean is MapperFactoryBean
        definition.getPropertyValues().add("mapperInterface", definition.getBeanClassName());
        definition.setBeanClass(MapperFactoryBean.class);

        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;
        }

　　一個BeanDefinition就這樣被完成了，並註冊到beanFactory裡。它有幾個重要的屬性

　　1 該Bean的class是MapperFactoryBean

　　2 它有屬性mapperInterface 這裡是me.gacl.dao.UserMapper

　　3 它有屬性sqlSessionFactory 就是在上一小節得到的sqlSessionFactory （Mybatis的原生類）

　　好了，到這裡後我們要分析的程式碼就是MapperFactoryBean

　　四MapperFactoryBean

　　這個類不得了，可以說不能執行Batch的原因就出在他身上

public class MapperFactoryBean<T> extends SqlSessionDaoSupport implements FactoryBean<T> {

  private Class<T> mapperInterface;

  private boolean addToConfig = true;

　　可以看出來MapperFactoryBean 本身就一個屬性mapperInterface 表示的是 me.gacl.dao.UserMapper

　　主要的功能和屬性都在SqlSessionDaoSupport

　　而且它本身就是一個FactoryBean 還是來看