实体类 [...] 中带注释的元素 [...] 上的 @JoinColumns 不完整

Question

我使用：NetBeans IDE 6.7.1、GlassFish v2.1、Oracle 10g XE、JAVA 6 SE、JAVA 5 EE。

我对 @ManyToMany 注释有问题：

@ManyToMany(fetch=FetchType.EAGER)
@JoinTable(name="CUST_RENT_MOVIE", joinColumns={@JoinColumn(name="CUST_ID")}, inverseJoinColumns={@JoinColumn(name="TITLE")})
private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();

GlassFish v2.1.1 的输出部分

Exception Description: The @JoinColumns on the annotated element [private java.util.Collection vc.domain.Customer.rents] from the entity class [class vc.domain.Customer] is incomplete. When the source entity class uses a composite primary key, a @JoinColumn must be specified for each join column using the @JoinColumns. Both the name and the referenceColumnName elements must be specified in each such @JoinColumn.
javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.1 (Build b31g-fcs (10/19/2009))): oracle.toplink.essentials.exceptions.EntityManagerSetupException
Exception Description: predeploy for PersistenceUnit [vc_pu] failed.

创建数据库的脚本部分：

CREATE table customer
(
cust_id NUMBER(5),    
CONSTRAINT cust_pk PRIMARY KEY (cust_id),
...
)

CREATE TABLE movie
(
title VARCHAR2(50) PRIMARY KEY,
...
)

CREATE TABLE cust_rent_movie
(
title VARCHAR2(50),
cust_id NUMBER(5),
rent_date DATE DEFAULT current_date NOT NULL,
return_date DATE,
CONSTRAINT cust_rent_movie_pk PRIMARY KEY (title, cust_id, rent_date),
CONSTRAINT CustRentMovie_movie_fk FOREIGN KEY (title) REFERENCES movie ON DELETE CASCADE,
CONSTRAINT CustRentMovie_cust_fk FOREIGN KEY (cust_id) REFERENCES customer ON DELETE CASCADE
)

Customer 类的代码

@Entity
@Table(name = "customer")
@SequenceGenerator(name="seq", sequenceName="cust_id_seq", allocationSize=1)
public class Customer implements Serializable
{

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")
    @Column(name="CUST_ID")
    private int id;


    @ManyToMany(fetch=FetchType.EAGER)
    @JoinTable(name="CUST_RENT_MOVIE", joinColumns={@JoinColumn(name="CUST_ID")}, inverseJoinColumns={@JoinColumn(name="TITLE")})
    private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();


    public Collection<CustRentMovie> getRents()
    {
        return rents;
    }

    public void setRents(Collection<CustRentMovie> rents)
    {
        this.rents = rents;
    }
...
}

---

错误地我将 CustRentMovie 类而不是 Movie So 作为类型放入集合中我将其更改

private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();

为

private Collection<Movie> movies = new ArrayList<Movie>();

Answer 1

CustomerRentMovie 的 PK 由三列组成（title、cust_id、rent_date）。 Toplink 表明您需要在 @JoinColumn 注释中将所有三个指定为连接列（当前您仅指定了 cust_id）。

将注释更改为类似的内容应该可以帮助您克服此错误。

@JoinTable(name = "CUST_RENT_MOVIE", joinColumns = {
    @JoinColumn(name = "CUST_ID"),
    @JoinColumn(name = "TITLE"),
    @JoinColumn(name = "RENT_DATE") }, inverseJoinColumns = { @JoinColumn(name = "TITLE") })
private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();

也就是说，帕斯卡的问题是有效的 - 看起来您打算建立从客户到电影的关系，而不是客户到 CUST_RENT_MOVIE 的关系。

Answer 2

我错误地将 CustRentMovie 类而不是 Movie 作为类型放入集合中，所以我将其更改

private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();

为

private Collection<Movie> movies = new ArrayList<Movie>();