Spring+Hibrenate中findByCriteria(criteria, start, limit)查询重复的问题解决

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1、问题出现的场景：两个Entity互相关联，我这里有两个类MessageMedel和CaseProcess，代码如下：

MessageModel类：

public class MessageModel extends Model {@Id@GeneratedValue@OrderBy("id")private long id;@ManyToMany(fetch = FetchType.EAGER)private List<Dict> recivers = new ArrayList<Dict>();@ManyToOneprivate Dict messageType;// 关联多个CaseProcess对象@OneToMany(cascade = CascadeType.ALL)private List<CaseProcess> caseProcessList;}

CaseProcess类：

@Entitypublic class CaseProcess extends Model {@Id@GeneratedValueprivate long id;@ManyToOneprivate Dict timerType;@ManyToOneprivate Dict caseGrade;@ManyToOneprivate Dict caseStatus;// 关联一个MessageModel对象@ManyToOneprivate MessageModel messageModel;}

其中MessageModel中caseProcessList关联多个CaseProcess，CaseProcess中关联一个MessageModel，当使用hibernateTemplate.findByCriteria(criteria, start, limit);分页查询时，会发生数据重复的现象。该方法参数中criteria是由以下方法获得的：

protected DetachedCriteria getConditions(String query,Map<String, String> queryMap) {return DetachedCriteria.forClass(this.entityClass);}

问题就出在了return DetachedCriteria.forClass(this.entityClass);一句，如果是在MessageModelService中，该句在查询MessageModel(记为m1)时，会级联查询CaseProcess，而CaseProcess中又关联着一个MessageModel(记为m2)，如果m1和m2在数据库中是同一条数据，则在hibernateTemplate.findByCriteria(criteria, start, limit);执行后，发生重复，解决办法是：

在MessageModelService中getConditions方法改写为：

@Overrideprotected DetachedCriteria getConditions(String query,Map<String, String> queryMap) {DetachedCriteria detachedCriteria = super.getConditions(query, queryMap);detachedCriteria.setFetchMode("caseProcessList", FetchMode.SELECT);return detachedCriteria;}

在CaseProcess中getConditions改写为：

@Overrideprotected DetachedCriteria getConditions(String query,Map<String, String> queryMap) {DetachedCriteria detachedCriteria = super.getConditions(query, queryMap);detachedCriteria.setFetchMode("messageModel", FetchMode.SELECT);return detachedCriteria;}

问题解决，这里特别感谢http://blog.sina.com.cn/s/blog_6af9cfe80101277m.html这篇文章的作者！