JPA @OneToMany 和复合 PK

Question

我正在从事一个 JPA 项目。我需要在具有三个主键的类上使用 @OneToMany 映射。您可以在此之后找到错误和类。

    javax.persistence.PersistenceException: No Persistence provider for EntityManager named JTA_pacePersistence: Provider named oracle.toplink.essentials.PersistenceProvider threw unexpected exception at create EntityManagerFactory: 
javax.persistence.PersistenceException
javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.EntityManagerSetupException
Exception Description: predeploy for PersistenceUnit [JTA_pacePersistence] failed.
Internal Exception: Exception [TOPLINK-7220] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.ValidationException
Exception Description: The @JoinColumns on the annotated element [private java.util.Set isd.pacepersistence.common.Action.permissions] from the entity class [class isd.pacepersistence.common.Action] 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.
    at oracle.toplink.essentials.internal.ejb.cmp3.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:643)
    at oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider.createEntityManagerFactory(EntityManagerFactoryProvider.java:196)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:110)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
    at isd.pacepersistence.common.DataMapper.(Unknown Source)
    at isd.pacepersistence.server.MainServlet.getDebugCase(Unknown Source)
    at isd.pacepersistence.server.MainServlet.doGet(Unknown Source)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:718)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:831)
    at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:411)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:290)
    at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:271)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:202)

这是我的课程的源代码：

行动：

@Entity
@Table(name="action")
public class Action {

  @Id
  @GeneratedValue(strategy=GenerationType.IDENTITY)
  private int num;

  @ManyToOne(cascade= { CascadeType.PERSIST, CascadeType.MERGE,
      CascadeType.REFRESH })
  @JoinColumn(name="domain_num")
  private Domain domain;

  private String name;
  private String description;

  @OneToMany
  @JoinTable(name="permission", joinColumns= { @JoinColumn(name="action_num", referencedColumnName="action_num", nullable=false, updatable=false) }, inverseJoinColumns= { @JoinColumn(name="num") })
  private Set<Permission> permissions;

  public Action() {
  }

权限：

@SuppressWarnings("serial")
@Entity
@Table(name="permission")
public class Permission implements Serializable {

  @EmbeddedId
  private PermissionPK primaryKey;

  @ManyToOne
  @JoinColumn(name="action_num", insertable=false, updatable=false)
  private Action action;

  @ManyToOne
  @JoinColumn(name="entity_num", insertable=false, updatable=false)
  private isd.pacepersistence.common.Entity entity;

  @ManyToOne
  @JoinColumn(name="class_num", insertable=false, updatable=false)
  private Clazz clazz;

  private String kondition;

  public Permission() {
  }

权限PK：

@SuppressWarnings("serial")
@Entity
@Table(name="permission")
public class Permission implements Serializable {

  @EmbeddedId
  private PermissionPK primaryKey;

  @ManyToOne
  @JoinColumn(name="action_num", insertable=false, updatable=false)
  private Action action;

  @ManyToOne
  @JoinColumn(name="entity_num", insertable=false, updatable=false)
  private isd.pacepersistence.common.Entity entity;

  @ManyToOne
  @JoinColumn(name="class_num", insertable=false, updatable=false)
  private Clazz clazz;

  private String kondition;

  public Permission() {
  }

Answer 1

早上好，

经过一整天搜索 JPA 和 @OneToMany 如何与复合 PK 配合使用后，我确实找到了解决方案。为了让它工作，我使用了@OneToMany 的参数 mappedBY。正如您在代码示例中看到的，我将权限集映射到权限类的属性操作。就是这样！简单易懂！

FF

动作类：

@Entity
@Table(name="action")
public class Action {

  @Id
  @GeneratedValue(strategy=GenerationType.IDENTITY)
  private int num;

  @ManyToOne(cascade= { CascadeType.PERSIST, CascadeType.MERGE,
      CascadeType.REFRESH })
  @JoinColumn(name="domain_num")
  private Domain domain;

  private String name;
  private String description;

  @OneToMany(mappedBy="action")
  private Set<Permission> permissions;

权限类

@SuppressWarnings("serial")
@Entity
@Table(name="permission")
public class Permission implements Serializable {

  @EmbeddedId
  private PermissionPK primaryKey;

  @ManyToOne
  @JoinColumn(name="action_num", insertable=false, updatable=false)
  private Action action;

Answer 2

错误消息似乎很清楚：您需要将复合 PK 的三列声明为 @JoinColum，并且必须为每列指定 name 和 referenceColumnName。我没有测试映射但试试这个：

@OneToMany
@JoinTable(name="permission", joinColumns= {
    @JoinColumn(name="col1", referencedColumnName="col1", nullable=false, updatable=false),
    @JoinColumn(name="col2", referencedColumnName="col2", ...),
    @JoinColumn(name="col3", referencedColumnName="col3", ...)
}, inverseJoinColumns= { @JoinColumn(name="num") })
private Set<Permission> permissions;