SqlSessionFactory

功能

用于创建SqlSession，相当于数据库连接池

生命周期

应该全局只有一个，作为单例存在

使用方法

参见： https://mybatis.org/mybatis-3/zh/java-api.html#SqlSessionFactory

SqlSession sqlSession = sqlSessionFactory.openSession(事务级别，执行器等)

SqlSession openSession(boolean autoCommit);//默认false
SqlSession openSession(Connection connection);
SqlSession openSession(TransactionIsolationLevel level);//默认null
SqlSession openSession(ExecutorType execType);
SqlSession openSession(ExecutorType execType, boolean autoCommit);
SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level);
SqlSession openSession(ExecutorType execType, Connection connection);