JPA分页查询

封装的实体类：

@Entity

@Table(name="active_alarm")

public class ActiveAlarm {

//告警编号

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

@Column(name="alarm_id")

private Integer alarmId;

//告警源

@Column(name="alarm_source")

private String alarmSource;

//告警级别,1:清除告警;4:提示告警;

//5:一般告警6:重要告警;7:紧急告警

@Column(name="alarm_level")

private Integer alarmLevel;

//告警最后发生时间

@Column(name="last_event_time")

private Date lastEventTime;

//重复告警次数

@Column(name="alarm_count")

private Integer alarmCount;

//告警信息

@Column(name="alarm_information")

private String alarmInformation;

//额外信息

@Column(name="additionalInformation")

private String additionalInformation;

//详细信息

@Column(name="additional_text")

private String additionalText;

//确认标志,0:未确认;1:已确认

@Column(name="ack_flag")

private Integer ackFlag;

//确认时间

@Column(name="ack_time")

private Date ackTime;

//确认用户

@Column(name="ack_user")

private String ackUser;

//清除标志,0:未清除;1:已清除

@Column(name="clear_flag")

private Integer clearFlag;

//清除时间

@Column(name="clear_time")

private Date clearTime;

//清除用户

@Column(name="clear_user")

private String clearUser;

//工单编号

@Column(name="order_no")

private Integer orderNo;

//告警数量

@Transient

private Integer alarmLevelCount;

}

DAO使用JPA注解进行查询：

@Repository("activeAlarmDao")

public interface ActiveAlarmDao extends

JpaRepository<ActiveAlarm, Integer>,

JpaSpecificationExecutor<ActiveAlarm>{

    /**

    * 通过告警源查询告警信息

    * @param alarmSource

    * @return

    */

@Query("select  alarm from ActiveAlarm alarm

  where alarm.alarmSource=(?1)")

    List<ActiveAlarm> queryByAlarmSource(String alarmSource);

    /**

    * 查询每种告警级别的告警数量

    * @return

    */

@Query("select alarm.alarmLevel,count(alarmLevel)

from  ActiveAlarm alarm

group by alarmLevel")

  List<Object[]> queryCountLeveL();

}

service曾的处理：

  /**

  * 查询告警级别的数量

  */

@Override

public List<ActiveAlarm> queryCountLeveL() {

List<Object[]> query=activeAlarmDao.queryCountLeveL();

List<ActiveAlarm> list=new ArrayList<ActiveAlarm>();

for(Object[] obj:query){

ActiveAlarm alarm=new ActiveAlarm();

alarm.setAlarmLevel(Integer.parseInt(obj[0].toString()));

alarm.setAlarmLevelCount(Integer.parseInt(obj[1].toString()));

list.add(alarm);

}

return list;

}