spring data jpa createNativeQuery 错误 Unknown entity

springdatajpa本地查询的时候，报错：org.hibernate.MappingException: Unknown entity: com.hzxc.guesssong.model.QuestionModel

解决办法

1.自定义对象类上添加@Entity注解，在其中一个属性上添加@Id标识注解。

2.如果jpa命名策略为：  jpa.naming.strategy: org.hibernate.cfg.ImprovedNamingStrategy，则sql语句中字段用下划线表示单词连接符。例如：java: userName = > sql: user_name.

示例：

import javax.persistence.Entity;
import javax.persistence.Id;

/**
 * Created by hdwang on 2018/6/6.
 * 问题模型
 */
@Entity
public class QuestionModel {

    @Id
    private int questionId;
    private int questionType;
    private int questionLevel;
    private int questionStatus;
    private String options;
    private String answer;
    private int songId;
    private String songSrcId;
    private String songName;
    private String songAuthor;
    private String songSourceUrl;
    private String songUrl;
    private int songStatus;

    public int getQuestionId() {
        return questionId;
    }

    public void setQuestionId(int questionId) {
        this.questionId = questionId;
    }

    public int getQuestionType() {
        return questionType;
    }

    public void setQuestionType(int questionType) {
        this.questionType = questionType;
    }

    public int getQuestionLevel() {
        return questionLevel;
    }

    public void setQuestionLevel(int questionLevel) {
        this.questionLevel = questionLevel;
    }

    public int getQuestionStatus() {
        return questionStatus;
    }

    public void setQuestionStatus(int questionStatus) {
        this.questionStatus = questionStatus;
    }

    public String getOptions() {
        return options;
    }

    public void setOptions(String options) {
        this.options = options;
    }

    public String getAnswer() {
        return answer;
    }

    public void setAnswer(String answer) {
        this.answer = answer;
    }

    public int getSongId() {
        return songId;
    }

    public void setSongId(int songId) {
        this.songId = songId;
    }

    public String getSongSrcId() {
        return songSrcId;
    }

    public void setSongSrcId(String songSrcId) {
        this.songSrcId = songSrcId;
    }

    public String getSongName() {
        return songName;
    }

    public void setSongName(String songName) {
        this.songName = songName;
    }

    public String getSongAuthor() {
        return songAuthor;
    }

    public void setSongAuthor(String songAuthor) {
        this.songAuthor = songAuthor;
    }

    public String getSongSourceUrl() {
        return songSourceUrl;
    }

    public void setSongSourceUrl(String songSourceUrl) {
        this.songSourceUrl = songSourceUrl;
    }

    public String getSongUrl() {
        return songUrl;
    }

    public void setSongUrl(String songUrl) {
        this.songUrl = songUrl;
    }

    public int getSongStatus() {
        return songStatus;
    }

    public void setSongStatus(int songStatus) {
        this.songStatus = songStatus;
    }
}

@Service
public class QuestionQueryServiceImpl implements QuestionQueryService {

    @PersistenceContext
    EntityManager entityManager;

    @Override
    public QuestionVO getOneRandomQuestionByLevel(int level) {
        String sql = "select  q1.id as question_id,q1.type as question_type,q1.`level` as question_level,q1.status as question_status,q1.options,q1.answer,"
                   +" s.id as song_id,s.song_src_id as song_src_id,s.name as song_name,s.author as song_author,s.source_url as song_source_url,s.url as song_url,s.status as song_status "
                   + " from question q1 inner join ( "
                   + "  select (min(q2.id) + round(rand()*(max(q2.id) - min(q2.id)))) as id from question q2 where q2.`level`= :level"
                   + " ) as t on q1.id >= t.id inner join song as s on q1.songid=s.id "
                   + " limit 1;";
        Map<String,Object> params = new HashMap<>();
        params.put("level",level);
        Query query = this.entityManager.createNativeQuery(sql, QuestionModel.class);
        this.setParameters(query,params);
        QuestionModel questionModel =  (QuestionModel) query.getSingleResult();
        QuestionVO vo = new QuestionVO();
        this.convertQuestionModelToQuestionVO(questionModel,vo);
        return vo;
    }

    private void convertQuestionModelToQuestionVO(QuestionModel model,QuestionVO vo){
        vo.setQuestionId(model.getQuestionId());
        vo.setQuestionLevel(model.getQuestionLevel());
        vo.setQuestionType(QuestionType.valueOf(model.getQuestionType()).getCnName());
        vo.setSongUrl(model.getQuestionStatus()==1?model.getSongUrl():model.getSongSourceUrl());
        vo.setOptions(JSONArray.parseArray(model.getOptions(),String.class));
    }

    /**
     * 给hql参数设置值
     * @param query 查询
     * @param params 参数
     */
    private void setParameters(Query query, Map<String,Object> params){
        for(Map.Entry<String,Object> entry:params.entrySet()){
            query.setParameter(entry.getKey(),entry.getValue());
        }
    }

}