Java 企业和联系人中JPA OneToMany的简单示例

请我需要一个简单的例子，一个JPA实体表示企业与联系人。 与rc_NoString有很多联系的企业； 看看我的代码，有问题吗

@Entity
public class Enterprises implements Serializable {
private static final long serialVersionUID = 1L;
@Id
private String rcNo;

@OneToMany(mappedBy = "enterprises", cascade=CascadeType.PERSIST, fetch=FetchType.EAGER)
private List<Contacts> contacts;

public void addContact(Contacts contact) {
    contacts.add(contact);
}

public String getRcNo() {
    return rcNo;
}

public void setRcNo(String rcNo) {
    this.rcNo = rcNo;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}.....

---

到底发生了什么？有什么问题吗。它在抱怨这段关系。谢谢，不过我想出来了。我花了很多时间！！！

@Entity
public class Contacts implements Serializable {
@ManyToOne
@JoinColumn(name="rcNo")
private Enterprises enterprises;

public Enterprises getEnterprises() {
    return enterprises;
}

public void setEnterprises(Enterprises enterprises) {
    this.enterprises = enterprises;
}

private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String fullName;
private String designation;
private String telephoneNo;
private String emailAddress;
.....