MyBatis懒加载数据（大批量数据处理）

使用范例

Cursor约定使用Iterator去懒加载数据，以时间换空间，非常适合处理通常无法容纳在内存中的数百万个项目查询。如果在 resultMap 中使用集合，则必须使用 resultMap 的 id 列对游标 SQL 查询进行排序(resultOrdered=“true”)。

//为了避免bug，手动管理一个session
try (SqlSession sqlSession = sqlSessionFactory.openSession()) {DDeviceShopIndexStatusMapper shopIndexStatusMapper = sqlSession.getMapper(DDeviceShopIndexStatusMapper.class);try (Cursor<DAlarmEventDTO> cursor = shopIndexStatusMapper.selectDevicesForShopClosed(commonProperties.getOpenShopStatus(), ABNORMAL.getCode())) {for (DAlarmEventDTO alarmEventDTO : cursor) {applicationContext.publishEvent(new DeviceShopClosedEvent(new Object(), alarmEventDTO));}} catch (IOException e) {log.error("shopStatusCheckJob cursor error:", e);}
}
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//方法定义
Cursor<DAlarmEventDTO> selectDevicesForShopClosed(@Param("shopStatus") List<String> shopStatus, @Param("status") Integer status);
============================
//xml写法与平常无异
<select id="selectDevicesForShopClosed" resultType="com.rome.device.monitor.admin.infrastructure.remote.dto.DAlarmEventDTO">select ddsb.device_key,....from d_device_detail dddleft join d_device_shop_bind ddsb on ddd.device_key = ddsb.device_key....where ....
</select>