example.createCriteria().andDatefieldLessThan(calendar.getTime());
answer = mapper.selectByExample(example);
assertEquals(5, answer.size());
calendar.set(Calendar.MINUTE, 12);
example.clear();
example.createCriteria().andTimefieldEqualTo(calendar.getTime());
answer = mapper.selectByExample(example);
assertEquals(1, answer.size());
example.clear();