BeanFactory和FactoryBean

• BeanFactory
  • BeanFactory的子接口ListableBeanFactory
  • 子接口ApplicationContext
  • Spring实现DefaultListableBeanFactory
• FactoryBean
  • 典型案例—mybatis的SqlSessionFactoryBean

BeanFactory#

是访问spring的IOC容器核心接口，提供访问spring容器中对象的功能，给IOC容器提供了基础规范。他里面有：

• BeanDefinition信息，根据这些BeanDefinition，Spring可以创建这些对象。
• 注册中心，创建的各种Bean都注册在这里
• Spring的依赖注入功能使用这个BeanFactory接口和子接口来实现。
• 会加载XML、注解，来配置Bean
• 核心方法有：各种重载的getBean、 getBeanProvider(Class)、 getType(name)、isSingleton(name)/isPrototype(name)、isTypeMatch(name, ResolvableType)
• 实现Bean生命周期回，全套的初始化方法以及它们的标准顺序是：
  • BeanNameAware的setBeanName
  • BeanClassLoaderAware的setBeanClassLoader
  • 实现BeanFactoryAware的setBeanFactory
  • EnvironmentAware的setEnvironment
  • EmbeddedValueResolverAware的setEmbeddedValueResolver
  • ResourceLoaderAware的setResourceLoader （仅适用于应用程序上下文中运行时）
  • ApplicationEventPublisherAware的setApplicationEventPublisher （仅适用于应用程序上下文中运行时）
  • MessageSourceAware的setMessageSource （仅适用于应用程序上下文中运行时）
  • 了ApplicationContextAware的setApplicationContext （仅适用于应用程序上下文中运行时）
  • ServletContextAware的setServletContext （仅适用于Web应用程序上下文中运行时）
  • postProcessBeforeInitialization BeanPostProcessor的方法的InitializingBean的afterPropertiesSet自定义的初始化方法定义
  • postProcessAfterInitialization BeanPostProcessor的方法
• 在一个bean工厂的关闭，下列生命周期方法适用于：
• posProcessBeforeDestruction DestructionAwareBeanPostProcessors的方法
• DisposableBean的destroy方法

BeanFactory的子接口ListableBeanFactory#

是BeanFactory的一个拓展，可以枚举所有的bean实例，所以是listable

下面是一堆可以listable的方法，一次可以拿出来一大堆bean的名称或者对象

• String[] getBeanDefinitionNames();
• 各种重载的String[] getBeanNamesForType(ResolvableType type);
• Map getBeansOfType( Class<T> type)
• Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType)

子接口ApplicationContext#

ApplicationContext作为ListableBeanFactory的子接口（还有一大堆别的接口）

public interface ApplicationContext extends EnvironmentCapable, ListableBeanFactory, HierarchicalBeanFactory,
		MessageSource, ApplicationEventPublisher, ResourcePatternResolver {

又有一大堆功能，提供了配置application的功能，还有

• 工厂方法来访问应用程序组件。 继承自ListableBeanFactory 。
• 以通用的方式的能力，加载文件资源。 继承了org.springframework.core.io.ResourceLoader接口。
• 发布事件注册的侦听器的能力。 继承了ApplicationEventPublisher接口。
• 有能力解决的消息，支持国际化。 继承了MessageSource接口。
• 继承自父上下文。 在子上下文定义将始终优先。 这意味着，例如，单个父上下文可以被整个web应用程序被使用，而每个servlet有其自己的子上下文无关的任何其他的servlet。
• 除了标准的org.springframework.beans.factory.BeanFactory生命周期的能力，ApplicationContext实现检测并调用ApplicationContextAware Bean以及ResourceLoaderAware ， ApplicationEventPublisherAware和MessageSourceAware。

Spring实现DefaultListableBeanFactory#

BeanFactory，以Factory结尾，表示它是一个工厂类(接口)， 它负责生产和管理bean的一个工厂。在Spring中，BeanFactory是IOC容器的核心接口，它的职责包括：实例化、定位、配置应用程序中的对象及建立这些对象间的依赖。

BeanFactory只是个接口，并不是IOC容器的具体实现，但是Spring容器给出了很多种实现，如 DefaultListableBeanFactory、XmlBeanFactory、ApplicationContext等，其中****XmlBeanFactory就是常用的一个，该实现将以XML方式描述组成应用的对象及对象间的依赖关系。XmlBeanFactory类将持有此XML配置元数据，并用它来构建一个完全可配置的系统或应用。

都是附加了某种功能的实现。 它为其他具体的IOC容器提供了最基本的规范，例如DefaultListableBeanFactory,XmlBeanFactory,ApplicationContext 等具体的容器都是实现了BeanFactory，再在其基础之上附加了其他的功能。

BeanFactory和ApplicationContext就是spring框架的两个IOC容器，现在一般使用ApplicationnContext，其不但包含了BeanFactory的作用，同时还进行更多的扩展。

FactoryBean#

一般情况下，Spring通过反射机制利用<bean>的class属性指定实现类实例化Bean，在某些情况下，实例化Bean过程比较复杂，如果按照传统的方式，则需要在<bean>中提供大量的配置信息。配置方式的灵活性是受限的，这时采用编码的方式可能会得到一个简单的方案。Spring为此提供了一个org.springframework.bean.factory.FactoryBean的工厂类接口，用户可以通过实现该接口定制实例化Bean的逻辑,底层是基于FactoryBeanRegistrySupport实现的。FactoryBean接口对于Spring框架来说占用重要的地位，Spring自身就提供了70多个FactoryBean的实现。

它们隐藏了实例化一些复杂Bean的细节，给上层应用带来了便利。从Spring3.0开始，FactoryBean开始支持泛型，即接口声明改为FactoryBean<T>的形式。

以Bean结尾，表示它是一个Bean，不同于普通Bean的是：它是实现了FactoryBean<T>接口的Bean，根据该Bean的ID从BeanFactory中获取的实际上是FactoryBean的getObject()返回的对象，而不是FactoryBean本身，如果要获取FactoryBean对象，请在id前面加一个&符号来获取。

例如自己实现一个FactoryBean，功能：用来代理一个对象，对该对象的所有方法做一个拦截，在调用前后都输出一行LOG，模仿ProxyFactoryBean的功能。

/**
 * 代理一个类，拦截该类的所有方法，在方法的调用前后进行日志的输出
 */
public class MyFactoryBean implements FactoryBean<Object>, InitializingBean, DisposableBean {

    private static final Logger logger = LoggerFactory.getLogger(MyFactoryBean.class);    
    private String interfaceName;    
    private Object target;    
    private Object proxyObj;    
    @Override
    public void destroy() throws Exception {
        logger.debug("destroy......");
    }
    @Override
    public void afterPropertiesSet() throws Exception {
        proxyObj = Proxy.newProxyInstance(
                this.getClass().getClassLoader(), 
                new Class[] { Class.forName(interfaceName) }, 
                new InvocationHandler() {                    
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                logger.debug("invoke method......" + method.getName());
                logger.debug("invoke method before......" + System.currentTimeMillis());
                Object result = method.invoke(target, args);
                logger.debug("invoke method after......" + System.currentTimeMillis());
                return result;            }            
        });
        logger.debug("afterPropertiesSet......");
    }

    @Override
    public Object getObject() throws Exception {
        logger.debug("getObject......");
        return proxyObj;
    }

    @Override
    public Class<?> getObjectType() {
        return proxyObj == null ? Object.class : proxyObj.getClass();
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    public String getInterfaceName() {
        return interfaceName;
    }

    public void setInterfaceName(String interfaceName) {
        this.interfaceName = interfaceName;
    }

    public Object getTarget() {
        return target;
    }

    public void setTarget(Object target) {
        this.target = target;
    }

    public Object getProxyObj() {
        return proxyObj;
    }

    public void setProxyObj(Object proxyObj) {
        this.proxyObj = proxyObj;
    }

}

public static void testFactoryBean(ConfigurableApplicationContext context){
        Car car = (Car) context.getBean(Car.class);
        System.out.println(car.toString());
        // 这里拿出来的才是CarFactoryBean
        System.out.println(context.getBean("&carFactoryBean").hashCode());
        // 这里拿出来的是Car
        System.out.println(context.getBean("carFactoryBean").getClass());
    }

典型案例—mybatis的SqlSessionFactoryBean#

使用来创建SqlSessionFactory对象的一个FactoryBean，如果没有他直接去创建DefaultSqlSessionFactory，里面需要依赖一个Configuration，这个里面又依赖org.apache.ibatis.mapping.Environment， Environment里面才有DataSource和TransactionFactory，这是一个很繁琐的链式依赖。

// 便捷创建SqlSessionFactory对象
public class SqlSessionFactoryBean
    implements FactoryBean<SqlSessionFactory>, InitializingBean, ApplicationListener<ApplicationEvent> {

  private static final Logger LOGGER = LoggerFactory.getLogger(SqlSessionFactoryBean.class);

  private static final ResourcePatternResolver RESOURCE_PATTERN_RESOLVER = new PathMatchingResourcePatternResolver();
  private static final MetadataReaderFactory METADATA_READER_FACTORY = new CachingMetadataReaderFactory();

  private Resource configLocation;

  private Configuration configuration;

  private Resource[] mapperLocations;

  private DataSource dataSource;

  private TransactionFactory transactionFactory;

  private Properties configurationProperties;

  private SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();

  private SqlSessionFactory sqlSessionFactory;

  // EnvironmentAware requires spring 3.1
  private String environment = SqlSessionFactoryBean.class.getSimpleName();

  private boolean failFast;

  private Interceptor[] plugins;

  private TypeHandler<?>[] typeHandlers;

  private String typeHandlersPackage;

  @SuppressWarnings("rawtypes")
  private Class<? extends TypeHandler> defaultEnumTypeHandler;

  private Class<?>[] typeAliases;

  private String typeAliasesPackage;

  private Class<?> typeAliasesSuperType;

  private LanguageDriver[] scriptingLanguageDrivers;

  private Class<? extends LanguageDriver> defaultScriptingLanguageDriver;

  // issue #19. No default provider.
  private DatabaseIdProvider databaseIdProvider;

  private Class<? extends VFS> vfs;

  private Cache cache;

  private ObjectFactory objectFactory;

  private ObjectWrapperFactory objectWrapperFactory;
    
    
     /**
   * 在spring的context刷新完毕的时候触发
   */
  @Override
  public void onApplicationEvent(ApplicationEvent event) {
    if (failFast && event instanceof ContextRefreshedEvent) {
      // fail-fast -> check all statements are completed
      this.sqlSessionFactory.getConfiguration().getMappedStatementNames();
    }
  }

    // 扫描包
  private Set<Class<?>> scanClasses(String packagePatterns, Class<?> assignableType) throws IOException {
    Set<Class<?>> classes = new HashSet<>();
    String[] packagePatternArray = tokenizeToStringArray(packagePatterns,
        ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
    for (String packagePattern : packagePatternArray) {
      Resource[] resources = RESOURCE_PATTERN_RESOLVER.getResources(ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
          + ClassUtils.convertClassNameToResourcePath(packagePattern) + "/**/*.class");
      for (Resource resource : resources) {
        try {
          ClassMetadata classMetadata = METADATA_READER_FACTORY.getMetadataReader(resource).getClassMetadata();
          Class<?> clazz = Resources.classForName(classMetadata.getClassName());
          if (assignableType == null || assignableType.isAssignableFrom(clazz)) {
            classes.add(clazz);
          }
        } catch (Throwable e) {
          LOGGER.warn(() -> "Cannot load the '" + resource + "'. Cause by " + e.toString());
        }
      }
    }
    return classes;
  }
    
    
    
      /**
  核心方法，创建一个SqlSessionFactory
   * Build a {@code SqlSessionFactory} instance.
   *
   * The default implementation uses the standard MyBatis {@code XMLConfigBuilder} API to build a
   * {@code SqlSessionFactory} instance based on a Reader. Since 1.3.0, it can be specified a {@link Configuration}
   * instance directly(without config file).
   *
   * @return SqlSessionFactory
   * @throws Exception
   *           if configuration is failed
   */
  protected SqlSessionFactory buildSqlSessionFactory() throws Exception {

    final Configuration targetConfiguration;

    XMLConfigBuilder xmlConfigBuilder = null;
    if (this.configuration != null) {
      targetConfiguration = this.configuration;
      if (targetConfiguration.getVariables() == null) {
        targetConfiguration.setVariables(this.configurationProperties);
      } else if (this.configurationProperties != null) {
        targetConfiguration.getVariables().putAll(this.configurationProperties);
      }
    } else if (this.configLocation != null) {
      xmlConfigBuilder = new XMLConfigBuilder(this.configLocation.getInputStream(), null, this.configurationProperties);
      targetConfiguration = xmlConfigBuilder.getConfiguration();
    } else {
      LOGGER.debug(
          () -> "Property 'configuration' or 'configLocation' not specified, using default MyBatis Configuration");
      targetConfiguration = new Configuration();
      Optional.ofNullable(this.configurationProperties).ifPresent(targetConfiguration::setVariables);
    }

    Optional.ofNullable(this.objectFactory).ifPresent(targetConfiguration::setObjectFactory);
    Optional.ofNullable(this.objectWrapperFactory).ifPresent(targetConfiguration::setObjectWrapperFactory);
    Optional.ofNullable(this.vfs).ifPresent(targetConfiguration::setVfsImpl);

    if (hasLength(this.typeAliasesPackage)) {
      scanClasses(this.typeAliasesPackage, this.typeAliasesSuperType).stream()
          .filter(clazz -> !clazz.isAnonymousClass()).filter(clazz -> !clazz.isInterface())
          .filter(clazz -> !clazz.isMemberClass()).forEach(targetConfiguration.getTypeAliasRegistry()::registerAlias);
    }

    if (!isEmpty(this.typeAliases)) {
      Stream.of(this.typeAliases).forEach(typeAlias -> {
        targetConfiguration.getTypeAliasRegistry().registerAlias(typeAlias);
        LOGGER.debug(() -> "Registered type alias: '" + typeAlias + "'");
      });
    }

    if (!isEmpty(this.plugins)) {
      Stream.of(this.plugins).forEach(plugin -> {
        targetConfiguration.addInterceptor(plugin);
        LOGGER.debug(() -> "Registered plugin: '" + plugin + "'");
      });
    }

    if (hasLength(this.typeHandlersPackage)) {
      scanClasses(this.typeHandlersPackage, TypeHandler.class).stream().filter(clazz -> !clazz.isAnonymousClass())
          .filter(clazz -> !clazz.isInterface()).filter(clazz -> !Modifier.isAbstract(clazz.getModifiers()))
          .forEach(targetConfiguration.getTypeHandlerRegistry()::register);
    }

    if (!isEmpty(this.typeHandlers)) {
      Stream.of(this.typeHandlers).forEach(typeHandler -> {
        targetConfiguration.getTypeHandlerRegistry().register(typeHandler);
        LOGGER.debug(() -> "Registered type handler: '" + typeHandler + "'");
      });
    }

    targetConfiguration.setDefaultEnumTypeHandler(defaultEnumTypeHandler);

    if (!isEmpty(this.scriptingLanguageDrivers)) {
      Stream.of(this.scriptingLanguageDrivers).forEach(languageDriver -> {
        targetConfiguration.getLanguageRegistry().register(languageDriver);
        LOGGER.debug(() -> "Registered scripting language driver: '" + languageDriver + "'");
      });
    }
    Optional.ofNullable(this.defaultScriptingLanguageDriver)
        .ifPresent(targetConfiguration::setDefaultScriptingLanguage);

    if (this.databaseIdProvider != null) {// fix #64 set databaseId before parse mapper xmls
      try {
        targetConfiguration.setDatabaseId(this.databaseIdProvider.getDatabaseId(this.dataSource));
      } catch (SQLException e) {
        throw new NestedIOException("Failed getting a databaseId", e);
      }
    }

    Optional.ofNullable(this.cache).ifPresent(targetConfiguration::addCache);

    if (xmlConfigBuilder != null) {
      try {
        xmlConfigBuilder.parse();
        LOGGER.debug(() -> "Parsed configuration file: '" + this.configLocation + "'");
      } catch (Exception ex) {
        throw new NestedIOException("Failed to parse config resource: " + this.configLocation, ex);
      } finally {
        ErrorContext.instance().reset();
      }
    }

    targetConfiguration.setEnvironment(new Environment(this.environment,
        this.transactionFactory == null ? new SpringManagedTransactionFactory() : this.transactionFactory,
        this.dataSource));

    if (this.mapperLocations != null) {
      if (this.mapperLocations.length == 0) {
        LOGGER.warn(() -> "Property 'mapperLocations' was specified but matching resources are not found.");
      } else {
        for (Resource mapperLocation : this.mapperLocations) {
          if (mapperLocation == null) {
            continue;
          }
          try {
            XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),
                targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());
            xmlMapperBuilder.parse();
          } catch (Exception e) {
            throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", e);
          } finally {
            ErrorContext.instance().reset();
          }
          LOGGER.debug(() -> "Parsed mapper file: '" + mapperLocation + "'");
        }
      }
    } else {
      LOGGER.debug(() -> "Property 'mapperLocations' was not specified.");
    }

    return this.sqlSessionFactoryBuilder.build(targetConfiguration);
  }

    
    // 下面都是一堆设置sqlSessionFactory属性的set方法，类似与<bean>的各个属性

  /**
   * Sets the ObjectFactory.
   *
   * @since 1.1.2
   * @param objectFactory
   *          a custom ObjectFactory
   */
  public void setObjectFactory(ObjectFactory objectFactory) {
    this.objectFactory = objectFactory;
  }

  /**
   * Sets the ObjectWrapperFactory.
   *
   * @since 1.1.2
   * @param objectWrapperFactory
   *          a specified ObjectWrapperFactory
   */
  public void setObjectWrapperFactory(ObjectWrapperFactory objectWrapperFactory) {
    this.objectWrapperFactory = objectWrapperFactory;
  }

  /**
   * Gets the DatabaseIdProvider
   *
   * @since 1.1.0
   * @return a specified DatabaseIdProvider
   */
  public DatabaseIdProvider getDatabaseIdProvider() {
    return databaseIdProvider;
  }

  /**
   * Sets the DatabaseIdProvider. As of version 1.2.2 this variable is not initialized by default.
   *
   * @since 1.1.0
   * @param databaseIdProvider
   *          a DatabaseIdProvider
   */
  public void setDatabaseIdProvider(DatabaseIdProvider databaseIdProvider) {
    this.databaseIdProvider = databaseIdProvider;
  }

  /**
   * Gets the VFS.
   *
   * @return a specified VFS
   */
  public Class<? extends VFS> getVfs() {
    return this.vfs;
  }

  /**
   * Sets the VFS.
   *
   * @param vfs
   *          a VFS
   */
  public void setVfs(Class<? extends VFS> vfs) {
    this.vfs = vfs;
  }

  /**
   * Gets the Cache.
   *
   * @return a specified Cache
   */
  public Cache getCache() {
    return this.cache;
  }

  /**
   * Sets the Cache.
   *
   * @param cache
   *          a Cache
   */
  public void setCache(Cache cache) {
    this.cache = cache;
  }

  /**
   * Mybatis plugin list.
   *
   * @since 1.0.1
   *
   * @param plugins
   *          list of plugins
   *
   */
  public void setPlugins(Interceptor... plugins) {
    this.plugins = plugins;
  }

  /**
   * Packages to search for type aliases.
   *
   * <p>
   * Since 2.0.1, allow to specify a wildcard such as {@code com.example.*.model}.
   *
   * @since 1.0.1
   *
   * @param typeAliasesPackage
   *          package to scan for domain objects
   *
   */
  public void setTypeAliasesPackage(String typeAliasesPackage) {
    this.typeAliasesPackage = typeAliasesPackage;
  }

  /**
   * Super class which domain objects have to extend to have a type alias created. No effect if there is no package to
   * scan configured.
   *
   * @since 1.1.2
   *
   * @param typeAliasesSuperType
   *          super class for domain objects
   *
   */
  public void setTypeAliasesSuperType(Class<?> typeAliasesSuperType) {
    this.typeAliasesSuperType = typeAliasesSuperType;
  }

  /**
   * Packages to search for type handlers.
   *
   * <p>
   * Since 2.0.1, allow to specify a wildcard such as {@code com.example.*.typehandler}.
   *
   * @since 1.0.1
   *
   * @param typeHandlersPackage
   *          package to scan for type handlers
   *
   */
  public void setTypeHandlersPackage(String typeHandlersPackage) {
    this.typeHandlersPackage = typeHandlersPackage;
  }

  /**
   * Set type handlers. They must be annotated with {@code MappedTypes} and optionally with {@code MappedJdbcTypes}
   *
   * @since 1.0.1
   *
   * @param typeHandlers
   *          Type handler list
   */
  public void setTypeHandlers(TypeHandler<?>... typeHandlers) {
    this.typeHandlers = typeHandlers;
  }

  /**
   * Set the default type handler class for enum.
   *
   * @since 2.0.5
   * @param defaultEnumTypeHandler
   *          The default type handler class for enum
   */
  public void setDefaultEnumTypeHandler(
      @SuppressWarnings("rawtypes") Class<? extends TypeHandler> defaultEnumTypeHandler) {
    this.defaultEnumTypeHandler = defaultEnumTypeHandler;
  }

  /**
   * List of type aliases to register. They can be annotated with {@code Alias}
   *
   * @since 1.0.1
   *
   * @param typeAliases
   *          Type aliases list
   */
  public void setTypeAliases(Class<?>... typeAliases) {
    this.typeAliases = typeAliases;
  }

  /**
   * If true, a final check is done on Configuration to assure that all mapped statements are fully loaded and there is
   * no one still pending to resolve includes. Defaults to false.
   *
   * @since 1.0.1
   *
   * @param failFast
   *          enable failFast
   */
  public void setFailFast(boolean failFast) {
    this.failFast = failFast;
  }

  /**
   * Set the location of the MyBatis {@code SqlSessionFactory} config file. A typical value is
   * "WEB-INF/mybatis-configuration.xml".
   *
   * @param configLocation
   *          a location the MyBatis config file
   */
  public void setConfigLocation(Resource configLocation) {
    this.configLocation = configLocation;
  }

  /**
   * Set a customized MyBatis configuration.
   *
   * @param configuration
   *          MyBatis configuration
   * @since 1.3.0
   */
  public void setConfiguration(Configuration configuration) {
    this.configuration = configuration;
  }

  /**
   * Set locations of MyBatis mapper files that are going to be merged into the {@code SqlSessionFactory} configuration
   * at runtime.
   *
   * This is an alternative to specifying "&lt;sqlmapper&gt;" entries in an MyBatis config file. This property being
   * based on Spring's resource abstraction also allows for specifying resource patterns here: e.g.
   * "classpath*:sqlmap/*-mapper.xml".
   *
   * @param mapperLocations
   *          location of MyBatis mapper files
   */
  public void setMapperLocations(Resource... mapperLocations) {
    this.mapperLocations = mapperLocations;
  }

  /**
   * Set optional properties to be passed into the SqlSession configuration, as alternative to a
   * {@code &lt;properties&gt;} tag in the configuration xml file. This will be used to resolve placeholders in the
   * config file.
   *
   * @param sqlSessionFactoryProperties
   *          optional properties for the SqlSessionFactory
   */
  public void setConfigurationProperties(Properties sqlSessionFactoryProperties) {
    this.configurationProperties = sqlSessionFactoryProperties;
  }

  /**
   * Set the JDBC {@code DataSource} that this instance should manage transactions for. The {@code DataSource} should
   * match the one used by the {@code SqlSessionFactory}: for example, you could specify the same JNDI DataSource for
   * both.
   *
   * A transactional JDBC {@code Connection} for this {@code DataSource} will be provided to application code accessing
   * this {@code DataSource} directly via {@code DataSourceUtils} or {@code DataSourceTransactionManager}.
   *
   * The {@code DataSource} specified here should be the target {@code DataSource} to manage transactions for, not a
   * {@code TransactionAwareDataSourceProxy}. Only data access code may work with
   * {@code TransactionAwareDataSourceProxy}, while the transaction manager needs to work on the underlying target
   * {@code DataSource}. If there's nevertheless a {@code TransactionAwareDataSourceProxy} passed in, it will be
   * unwrapped to extract its target {@code DataSource}.
   *
   * @param dataSource
   *          a JDBC {@code DataSource}
   *
   */
  public void setDataSource(DataSource dataSource) {
    if (dataSource instanceof TransactionAwareDataSourceProxy) {
      // If we got a TransactionAwareDataSourceProxy, we need to perform
      // transactions for its underlying target DataSource, else data
      // access code won't see properly exposed transactions (i.e.
      // transactions for the target DataSource).
      this.dataSource = ((TransactionAwareDataSourceProxy) dataSource).getTargetDataSource();
    } else {
      this.dataSource = dataSource;
    }
  }

  /**
   * Sets the {@code SqlSessionFactoryBuilder} to use when creating the {@code SqlSessionFactory}.
   *
   * This is mainly meant for testing so that mock SqlSessionFactory classes can be injected. By default,
   * {@code SqlSessionFactoryBuilder} creates {@code DefaultSqlSessionFactory} instances.
   *
   * @param sqlSessionFactoryBuilder
   *          a SqlSessionFactoryBuilder
   *
   */
  public void setSqlSessionFactoryBuilder(SqlSessionFactoryBuilder sqlSessionFactoryBuilder) {
    this.sqlSessionFactoryBuilder = sqlSessionFactoryBuilder;
  }

  /**
   * Set the MyBatis TransactionFactory to use. Default is {@code SpringManagedTransactionFactory}
   *
   * The default {@code SpringManagedTransactionFactory} should be appropriate for all cases: be it Spring transaction
   * management, EJB CMT or plain JTA. If there is no active transaction, SqlSession operations will execute SQL
   * statements non-transactionally.
   *
   * <b>It is strongly recommended to use the default {@code TransactionFactory}.</b> If not used, any attempt at
   * getting an SqlSession through Spring's MyBatis framework will throw an exception if a transaction is active.
   *
   * @see SpringManagedTransactionFactory
   * @param transactionFactory
   *          the MyBatis TransactionFactory
   */
  public void setTransactionFactory(TransactionFactory transactionFactory) {
    this.transactionFactory = transactionFactory;
  }

  /**
   * <b>NOTE:</b> This class <em>overrides</em> any {@code Environment} you have set in the MyBatis config file. This is
   * used only as a placeholder name. The default value is {@code SqlSessionFactoryBean.class.getSimpleName()}.
   *
   * @param environment
   *          the environment name
   */
  public void setEnvironment(String environment) {
    this.environment = environment;
  }

  /**
   * Set scripting language drivers.
   *
   * @param scriptingLanguageDrivers
   *          scripting language drivers
   * @since 2.0.2
   */
  public void setScriptingLanguageDrivers(LanguageDriver... scriptingLanguageDrivers) {
    this.scriptingLanguageDrivers = scriptingLanguageDrivers;
  }

  /**
   * Set a default scripting language driver class.
   *
   * @param defaultScriptingLanguageDriver
   *          A default scripting language driver class
   * @since 2.0.2
   */
  public void setDefaultScriptingLanguageDriver(Class<? extends LanguageDriver> defaultScriptingLanguageDriver) {
    this.defaultScriptingLanguageDriver = defaultScriptingLanguageDriver;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void afterPropertiesSet() throws Exception {
    notNull(dataSource, "Property 'dataSource' is required");
    notNull(sqlSessionFactoryBuilder, "Property 'sqlSessionFactoryBuilder' is required");
    state((configuration == null && configLocation == null) || !(configuration != null && configLocation != null),
        "Property 'configuration' and 'configLocation' can not specified with together");

    this.sqlSessionFactory = buildSqlSessionFactory();
  }


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

    return this.sqlSessionFactory;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Class<? extends SqlSessionFactory> getObjectType() {
    return this.sqlSessionFactory == null ? SqlSessionFactory.class : this.sqlSessionFactory.getClass();
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean isSingleton() {
    return true;
  }

 

}

https://www.cnblogs.com/aspirant/p/9082858.html