Mybatis返回结果封装map过程解析

<select id="listLessonSumByCourseIdList" resultType="java.util.HashMap">
 SELECT course_id, count(1)
 FROM lesson
 WHERE status = 0
 GROUP BY course_id;
</select>

<select id="listLessonSumByCourseIdList" resultType="java.util.HashMap">
 SELECT course_id as 'key', count(1) as 'value'
 FROM lesson
 WHERE type != 1 AND status = 0
 GROUP BY course_id;
</select>

public Map<Long, Long> listLessonSumByCourseIdList() {
 Map<Long, Long> map = new HashMap<>();
 List<HashMap<String, Object>> list = courseDao.listLessonSumByCourseIdList();
 if (list != null && !list.isEmpty()) {
  for (HashMap<String, Object> map1 : list) {
   Long key = null;
   Long value = null;
   for (Map.Entry<String, Object> entry : map1.entrySet()) {
    if ("key".equals(entry.getKey())) {
     key = (Long) entry.getValue();
    } else if ("value".equals(entry.getKey())) {
     value = (Long) entry.getValue();
    }
   }
   map.put(key, value);
  }
 }
 return map;
}