二级缓冲

二级缓存需要三部缺一不可

大配置：

小配置

实体类继承serializable

单侧：

 @Test
    //二级缓存
    public void hc(){
      SqlSession session = util.getsql();
      IStudentDao dao = session.getMapper(IStudentDao.class);
      Studentinfo studentinfo = dao.getstudentByid(6);
      System.out.println(studentinfo.getStuName());
      session.close();

      System.out.println("===================================================");

      SqlSession session2 = util.getsql();
      IStudentDao dao2 = session2.getMapper(IStudentDao.class);
      Studentinfo studentinfo1 = dao2.getstudentByid(6);
      System.out.println(studentinfo1.getStuName());


  }
}