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我如何在eclipselink中做一個簡單的連接查詢？我想收到ArrayList; 例如，我有兩個實體：Eclipse鏈接簡單連接
public class A implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
private Long id;
@Column(name = "value")
private String value;
@OneToMany(mappedBy = "aid")
private Collection<B> bCollection;
}
public class B implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
private Long id;
@JoinColumn(name = "a_id", referencedColumnName = "id")
@ManyToOne
private A aid;
}
我想是這樣執行的查詢：
Select * From A a Join B b ON a.id = b.a_id Where a.value = '1';
我這樣做：
EntityManager em = createEntityManager();
Query q = em.createQuery("Select a From A a Where a.value = 1");
q.setHint("eclipselink.join-fetch", "a.bCollection");
Object result = q.getResultList();
而且我收到一個對象，它有一個鏈接到B對象（bCollection），它在A對象上有一個鏈接（aid），並且是無限期的。這是正常的嗎？