IllegalArgumentException:期望IdClass映射

Question

在部署我的应用程序期间,我发生在该异常上.我的应用程序中有很多课程,我不知道我必须放在@IdClass哪里,无论如何这个例外意味着什么.我正在使用Hibernate 4.1和JBoss AS 7.1

12:10:23,761 INFO  [org.hibernate.engine.jdbc.internal.LobCreatorBuilder] (MSC service thread 1-5) HHH000424: Disabling contextual LOB creation as createClob() method threw error : java.lang.reflect.InvocationTargetException
12:10:24,075 ERROR [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-5) HHH000389: Unsuccessful: drop sequence hibernate_sequence
12:10:24,076 ERROR [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-5) ERROR: sequence "hibernate_sequence" does not exist
12:10:24,281 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-5) MSC00001: Failed to start service jboss.persistenceunit."kladr.ear/kladr-ejb-1.0-SNAPSHOT.jar#primary": org.jboss.msc.service.StartException in service jboss.persistenceunit."kladr.ear/kladr-ejb-1.0-SNAPSHOT.jar#primary": Failed to start service
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1767) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_35]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_35]
    at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_35]
Caused by: java.lang.IllegalArgumentException: expecting IdClass mapping
    at org.hibernate.ejb.metamodel.AttributeFactory$3.resolveMember(AttributeFactory.java:878)
    at org.hibernate.ejb.metamodel.AttributeFactory$4.resolveMember(AttributeFactory.java:915)
    at org.hibernate.ejb.metamodel.AttributeFactory.determineAttributeMetadata(AttributeFactory.java:423)
    at org.hibernate.ejb.metamodel.AttributeFactory.buildAttribute(AttributeFactory.java:91)
    at org.hibernate.ejb.metamodel.MetadataContext.wrapUp(MetadataContext.java:214)
    at org.hibernate.ejb.metamodel.MetamodelImpl.buildMetamodel(MetamodelImpl.java:64)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:91)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:904)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:889)
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:73)
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl.createContainerEntityManagerFactory(PersistenceUnitServiceImpl.java:162)
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl.start(PersistenceUnitServiceImpl.java:85)
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
    ... 3 more

Answer 1

@IdClass注释用于定义包含id的Class.即,这通常用于定义复合键的情况.即多个属性的关键复合.如果是这样的话,那就是我们这样做的方式.看一下下面的例子..我们将一个类定义为IdClass并使用@Id's来定义不同的Id s for thisIdClass`.

示例:

@Entity
@IdClass(AssignedRoleId.class)
public class AssignedRole
{
  @Id
  @ManyToOne
  private User userId;

  @Id
  @ManyToOne  
  private Role roleId;

  private Date dateAssigned;
}

希望这可以帮助.

Answer 2

进一步详细说明@Mukul的正确答案@IdClass应具有以下属性：

1. 它应该实现Serializable
2. 它应该具有接受ID的构造函数（即与关联的字段@Id）
3. 它应该覆盖equals和hashCode

将此类作为实体的静态内部类有时很有用，下面是一个示例：

@Entity 
@IdClass(AssignedRoleId.class)
public class AssignedRole
{ 
    @Id
    @ManyToOne
    private User userId;

    @Id
    @ManyToOne
    private Role roleId;

    private Date dateAssigned;

    public static class AssignedRoleId implements Serializable {

        private User userId;
        private Role roleId;

        public AssignedRoleId() {}

        public AssignedRoleId(User userId, Role roleId) {
            this.userId = userId;
            this.roleId = roleId;
        }

        @Override
        public boolean equals(Object o) {

            if (o == this) {
                return true;
            }
            if (!(o instanceof AssignedRole)) {
                return false;
            }
            AssignedRole assignedRole = (AssignedRole) o;
            return Objects.equals(userId, assignedRole.getUserId()) &&
                   Objects.equals(roleId, assignedRole.getRoleId());
        }

        @Override
        public int hashCode() {
            return Objects.hash(userId, roleId);
        }
   }
}