从三个主要的对象SqlSessionFactoryBuilder->SqlSessionFactory->SqlSession说起

            inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

1. 读取全局配置文件

   inputStream = Resources.getResourceAsStream(resource);

2. 创建了一个SqlSessionFactoryBuilder对象

3. 调用.getResourceAsStream(resource)方法,完成相关配置并创建SqlSessionFactory对象

   //点击进入可知对XML文件进行了解析,从而获得了XMLConfiguration,且该对象继承自Configuration对象.进入下一步的build查看
   public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {
   SqlSessionFactory var5;
   try {
   XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
   var5 = this.build(parser.parse());
   } catch (Exception var14) {
   throw ExceptionFactory.wrapException("Error building SqlSession.", var14);
   } finally {
   ErrorContext.instance().reset();

           try {
               inputStream.close();
           } catch (IOException var13) {
           }
   }
   
   return var5;
   }

   //加Configuration对象加载给SqlSessionFactory对象,完成了SqlSessionFactory的创建
   public SqlSessionFactory build(Configuration config) {
   return new DefaultSqlSessionFactory(config);
   }

4. 调用SqlSessionFactory对象的openSession方法完SqlSession对象的实例化

   //往下:可以看出是先继承了Configuration中的Environment,完成了transaction相关的操作,继而产生executor,最后才完成了SqlSession的实例化,能力有限,这里就不深究了
   private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
   Transaction tx = null;

       DefaultSqlSession var8;
       try {
           Environment environment = this.configuration.getEnvironment();
           TransactionFactory transactionFactory = this.getTransactionFactoryFromEnvironment(environment);
           tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);
           Executor executor = this.configuration.newExecutor(tx, execType);
           var8 = new DefaultSqlSession(this.configuration, executor, autoCommit);
       } catch (Exception var12) {
           this.closeTransaction(tx);
           throw ExceptionFactory.wrapException("Error opening session.  Cause: " + var12, var12);
       } finally {
           ErrorContext.instance().reset();
       }
   return var8;
   }

5. CURD的执行(产生错误就回滚)

6. 检测是否执行(产生错误就回滚)

7. 提交

   8.关闭