 
        SqlSessionFactory sqlSessionFactory = SqlSessionUtils.getSqlSessionFactory();
    SqlSession sqlSession = sqlSessionFactory.openSession();
    SqlSession sqlSession2 = sqlSessionFactory.openSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    User userById = mapper.findUserById(42);
    System.out.println(userById.hashCode()); //936580213
    sqlSession.close();
    UserMapper mapper2 = sqlSession2.getMapper(UserMapper.class);
    User userById2 = mapper2.findUserById(42);
    System.out.println(userById.hashCode()); //936580213
    sqlSession2.close();
    System.out.println(userById == userById2); //false要比较是否相同的话,要实现自己的hashCode()和equals()方法。
另外,还注意类加载器是不是相同。