Hibernate多对多集合对象关联查询的问题

Question

同志们，问一个问题，在hibernate里面.我有一个group类表示群组，person类表示联系人，它们是双向多对多关系 ，如果我想查询联系人姓名包括‘tom’的群组列表，那么hql怎么写？

public class Person implements  Comparable{

    private int id;

    private String name;

    private String phone;

    private String address;

    private Set groups;

}

public class Group implements java.lang.Comparable{

    private int id;

    private String name;

    private String description;

    private Set persons;

}

groups=session.createQuery("from Group as g  inner join g.persons as p  where p.name=?").setString(0, name).list();

这种方法返回的将是一个 Object列表..
问题补充

Blithe 写道

groups.get(0)

首先谢谢，经过调试发现，

List result=session.createQuery("from Group as g  inner join g.persons as p  where p.name=?").setString(0, name).list();

result中的每一个条目是一个Object数组，此Object数组有两个元素，Group和Person，所以解决的办法是

        List result=session.createQuery("from Group as g  inner join g.persons as p  where p.name=?").setString(0, name).list();


        groups=new ArrayList();

        int size=result.size();

        for(int i=0;i<size;i++){

            Object[] item=(Object[])result.get(i);

            groups.add(item[0]);

        }

不过显然这种办法的性能和效率太低了，有没有更好的办法？还是直接用SQL？
问题补充
试了试，我觉得正解应该是这样的

List crs=session.createCriteria(Group.class).createAlias("persons", "p").add(Restrictions.eq("p.name", name)).list();

用HQL实现我做不出来了，不知道有没有高手能够用HQL把上面的条件查询翻译下。
问题补充：
上面的条件查询翻译成hql应该是

from Group where persons.name=?

但是执行时会报错

org.hibernate.QueryException: illegal attempt to dereference collection [{synthetic-alias}{non-qualified-property-ref}persons] with element property reference [name] [from com.iflysse.addressbook.domain.Group where persons.name=?]

    org.hibernate.hql.ast.tree.DotNode$1.buildIllegalCollectionDereferenceException(DotNode.java:46)

    org.hibernate.hql.ast.tree.DotNode.checkLhsIsNotCollection(DotNode.java:513)

    org.hibernate.hql.ast.tree.DotNode.resolve(DotNode.java:221)

    org.hibernate.hql.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:94)

    org.hibernate.hql.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:90)

    org.hibernate.hql.ast.HqlSqlWalker.resolve(HqlSqlWalker.java:728)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.expr(HqlSqlBaseWalker.java:1216)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.exprOrSubquery(HqlSqlBaseWalker.java:4041)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.comparisonExpr(HqlSqlBaseWalker.java:3525)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1762)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.whereClause(HqlSqlBaseWalker.java:776)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:577)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:281)

    org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:229)

    org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:228)

    org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:160)

    org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)

    org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)

    org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)

    org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)

    org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)

    org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:112)

    org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)

    com.iflysse.addressbook.dao.GroupDao.search(GroupDao.java:68)

    com.iflysse.addressbook.action.GroupAction.test(GroupAction.java:180)

    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

    java.lang.reflect.Method.invoke(Unknown Source)

    org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)

    org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)

    org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)

    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)

    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)

    org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)

    javax.servlet.http.HttpServlet.service(HttpServlet.java:690)

    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

    com.ilfysse.utils.HibernateSessionInViewFilter.doFilter(HibernateSessionInViewFilter.java:38)

看来是不是persons别名的问题？

Answer 1

select p.groups from Person p where p.name=?