JPA中的@ManyToMany映射抛出异常[EclipseLink-6076]

Question

我使用Eclipse 2.5.2在Oracle 11g数据库中开发了简单的JPA2.1应用程序。以下是我的情景 - 有两个实体 @ManyToMany 关系

• 俱乐部
• 人

Club.java

@Entity(name = "CLUB")
public class Club {
    @Id
    private int c_id;
    private String c_name;
    @ManyToMany(cascade={CascadeType.PERSIST, CascadeType.MERGE}, 
                fetch=FetchType.EAGER)
    @JoinTable(name = "CLUB_PEOPLE", 
               joinColumns=@JoinColumn(name="c_id", referencedColumnName="c_id"),
               inverseJoinColumns=@JoinColumn(name="p_id")) 
    private Set<People> people=new HashSet<People>();

    public int getC_id() {
        return c_id;
    }
    public void setC_id(int c_id) {
        this.c_id = c_id;
    }
    public String getC_name() {
        return c_name;
    }
    public void setC_name(String c_name) {
        this.c_name = c_name;
    }
    public Set<People> getPeople() {
        return people;
    }
    public void setPeople(Set<People> people) {
        this.people = people;
    }
    public void addPeople(People p){
        getPeople().add(p);
    }
}

的 People.Java

@Entity(name="people")
public class People{
    @Id     
    private int p_id;   
    private String name ;

    @ManyToMany(mappedBy="people")
    private Set<Club> club;

    public int getP_id() {
        return p_id;
    }
    public void setP_id(int p_id) {
        this.p_id = p_id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

Client.java

public class Client1 {
    public static void main(String[] args) {
        EntityManagerFactory emf = 
            Persistence.createEntityManagerFactory("JPA-Query");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Club> cq = cb.createQuery(Club.class).distinct(true);
        Root<Club> root = cq.from(Club.class);

        final List<Predicate> requiredCriteria = new ArrayList<Predicate>();
        final Join people = root.join("people", JoinType.LEFT);

        requiredCriteria.add(cb.or(cb.isNull(people)));
        requiredCriteria.add(cb.isNull(people.get("name")));
        requiredCriteria.add(cb.equal(people.get("name"), "people1"));

        TypedQuery<Club> q = em.createQuery(
            cq.where(cb.or(requiredCriteria
                .toArray(new Predicate[requiredCriteria.size()])
            ))
        );

        List<Club> allemps = q.getResultList();
        em.close();          
        emf.close();
    }
}

表 -

CREATE TABLE Club(
    c_id number NOT NULL,
    c_name VARCHAR2(20)
) 
ALTER TABLE Club ADD CONSTRAINT CLUGGRPPK PRIMARY KEY (c_id);

CREATE TABLE People(
    p_id number NOT NULL,
    name VARCHAR2(20) 
) 
ALTER TABLE People ADD CONSTRAINT PEOPLEGRPPK PRIMARY KEY (p_id);

CREATE TABLE CLUB_PEOPLE
( 
    C_ID number,
    P_ID number,
    CONSTRAINT CLUB_PEOPLEPK PRIMARY KEY (C_ID, P_ID),
    CONSTRAINT GROUP_FK FOREIGN KEY("C_ID") 
        REFERENCES "CLUB"("C_ID") ON DELETE CASCADE,
    CONSTRAINT PEOPLE_FK FOREIGN KEY("P_ID") 
        REFERENCES "PEOPLE"("P_ID") ON DELETE CASCADE
)

当我运行Client.java时，它会抛出异常

Exception Description: Object comparisons can only be used with OneToOneMappings.  Other mapping comparisons must be done through query keys or direct attribute level comparisons. 
Mapping: [org.eclipse.persistence.mappings.ManyToManyMapping[people]]
Expression: [
Query Key people
   Base ManyToMany.Club]
Query: ReadAllQuery(referenceClass=Club )
javax.persistence.PersistenceException: Exception [EclipseLink-6076] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.QueryException
Exception Description: Object comparisons can only be used with OneToOneMappings.  Other mapping comparisons must be done through query keys or direct attribute level comparisons. 
Mapping: [org.eclipse.persistence.mappings.ManyToManyMapping[people]] 
Expression: [
Query Key people
   Base ManyToMany.Club]
Query: ReadAllQuery(referenceClass=Club )
    at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:480)
    at ManyToMany.Client.main(Client.java:75)
Caused by: Exception [EclipseLink-6076] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.QueryException
Exception Description: Object comparisons can only be used with OneToOneMappings.  Other mapping comparisons must be done through query keys or direct attribute level comparisons. 
Mapping: [org.eclipse.persistence.mappings.ManyToManyMapping[people]] 
Expression: [
Query Key people
   Base ManyToMany.Club]
Query: ReadAllQuery(referenceClass=Club )
    at org.eclipse.persistence.exceptions.QueryException.unsupportedMappingForObjectComparison(QueryException.java:1170)

请帮我解决上述问题。提前致谢。