【Mybatis源码阅读之SqlSessionFactory 何时实例化】

 //mybatis的配置文件

String resource = "conf.xml";

//使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）

// InputStream is = App.class.getClassLoader().getResourceAsStream(resource);

Reader reader = Resources.getResourceAsReader(resource);

//构建sqlSession的工厂

SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

//使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）

//Reader reader = Resources.getResourceAsReader(resource); 

//构建sqlSession的工厂

//SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

//创建能执行映射文件中sql的sqlSession

SqlSession session = sessionFactory.openSession();

 

二、认识接口

public interface SqlSessionFactory {

    疑问：接口何时实例化??

}

 

public SqlSessionFactory build(Reader reader) {

    return build(reader, null, null);

}

 

 public SqlSessionFactory build(Reader reader, String environment, Properties props) {

    return build(new ReaderInputStream(reader), environment, props);

 }

 

public SqlSessionFactory build(InputStream inputStream, String environment, Properties props) {

    try {

      XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, props);

      Configuration config = parser.parse();

      return build(config);

    } catch (Exception e) {

      throw ExceptionFactory.wrapException("Error building SqlSession.", e);

    } finally {

      ErrorContext.instance().reset();

      try {

        inputStream.close();

      } catch (IOException e) {

        // Intentionally ignore.  Prefer previous error.

      }

    }

 }

 

 public SqlSessionFactory build(Configuration config) {

     //接口此时完成实例化

    return new DefaultSqlSessionFactory(config);

  }