JPA 2.0：@AttributeOverrides和继承的属性相互之间没有很好的相关性

时间：2013-01-20 00:09:37

标签： jpa jpa-2.0

我需要帮助解决下一个与此one非常相似的问题。但是，建议的解决方案在我的情况下不起作用。我有一个被标记为@Embbedable的类RoadDistance和一个RoadMetricLoader类，它也是@Embbedable，它包含两个类型为RoadDistante的属性。还有类RoadConnection，它是一个实体，包含RoadmetricLoader类型的属性。我没有成功覆盖RoadMeistanceLoader的RoadMetricLoader属性（@AttributeOverride）（我没有在表ROAD_CONNECTION中获得ROAD_ESTIMATED_DISTANCE_VALUE，ROAD_ESTIMATED_DISTANCE_UNIT_ID，ROAD_REAL_DISTANCE_VALUE和ROAD_REAL_DISTANCE_UNIT_ID字段）

数据库是MySQL 5.2.21，用于JPA 2.0的库是EclipseLink 2.4.1中的库

我尝试了不同的选项，但没有一个可行。我在下面的代码中显示了注释块中的所有选项。取消注释时，一个选项会保留其他选项。这些是我在每种情况下得到的结果：

选项1 ：它不会返回任何错误，但在表ROAD_CONNECTION中我只得到两个错误：VALUE和UNIT_ID。

选项2 ：与选项1相同的结果。

选项3 ：这是我的第一个赌注（请参阅official documentation example 2，以及上面已经指明的链接）但我收到了下一个错误

Local Exception Stack: 
Exception [EclipseLink-30005] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while searching for persistence archives with ClassLoader: sun.misc.Launcher$AppClassLoader@138d107f
Internal Exception: javax.persistence.PersistenceException: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [jamUnit] failed.
Internal Exception: Exception [EclipseLink-7309] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The attribute named [estimatedRoadDistance.unit] from the embeddable class [class net.question.RoadMetricLoader] is not a valid mapping to use with an attribute override for the attribute [metricLoader] on class [class net.question.RoadConnection].
    at org.eclipse.persistence.exceptions.PersistenceUnitLoadingException.exceptionSearchingForPersistenceResources(PersistenceUnitLoadingException.java:127)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:118)
    at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
    at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
    (...)

选项4 ：与选项1和2相同。

选项5 ：

Local Exception Stack: 
Exception [EclipseLink-30005] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while searching for persistence archives with ClassLoader: sun.misc.Launcher$AppClassLoader@12360be0
Internal Exception: javax.persistence.PersistenceException: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [jamUnit] failed.
Internal Exception: Exception [EclipseLink-7309] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The attribute named [unit] from the embeddable class [class net.question.RoadDistance] is not a valid mapping to use with an attribute override for the attribute [estimatedRoadDistance] on class [class net.question.RoadMetricLoader].
    at org.eclipse.persistence.exceptions.PersistenceUnitLoadingException.exceptionSearchingForPersistenceResources(PersistenceUnitLoadingException.java:127)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:118)
    at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
    at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
    (...)

@Entity
@Table(name="UNIT")
public class Unit {

    private Long id;
    private String name;
    private String measureSystemCode;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO, generator="UNIT_SEQ_GENERATOR")
    @SequenceGenerator(name="UNIT_SEQ_GENERATOR", sequenceName="UNIT_SEQ")
    @Column(name = "ID")
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @Column(name = "NAME", nullable = false)
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Column(name = "MEASURE_SYSTEM_CODE", nullable = false)
    public String getMeasureSystemCode() {
        return measureSystemCode;
    }

    public void setMeasureSystemCode(String measureSystemCode) {
        this.measureSystemCode = measureSystemCode;
    }

}

@MappedSuperclass
public abstract class Metric<V extends Comparable<V>> {

    private V value;
    private Unit unit;

    @Column(name = "VALUE", nullable = false)
    public V getValue() {
        return value;
    }

    public void setValue(V value) {
        this.value = value;
    }

    @ManyToOne
    @JoinColumn(name = "UNIT_ID", nullable = false)
    public Unit getUnit() {
        return unit;
    }

    public void setUnit(Unit unit) {
        this.unit = unit;
    }

}

@MappedSuperclass
public abstract class ScalarPhysicalMetric<M extends Number & Comparable<M>>
extends Metric<M> {

}

@Embeddable
public final class RoadDistance extends ScalarPhysicalMetric<Double> {

}

/*
// -##----------- OPTION 4 ---------->
@AttributeOverrides({
    @AttributeOverride(name = "estimatedRoadDistance.value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE")),
    @AttributeOverride(name = "estimatedRoadDistance.unit", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID")),
    @AttributeOverride(name = "realRoadDistance.value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE")),
    @AttributeOverride(name = "realRoadDistance.unit", column = @Column(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
})
// <---------- OPTION 4 -----------##-
*/
@Embeddable
public final class RoadMetricLoader {

    private RoadDistance estimatedRoadDistance;
    private RoadDistance realRoadDistance;

    @Embedded
    /*
    // -##----------- OPTION 5 ---------->
    @AttributeOverrides({
        @AttributeOverride(name = "value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE")),
        @AttributeOverride(name = "unit", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID"))
    })
    // <---------- OPTION 5 -----------##-
    */
    public RoadDistance getEstimatedRoadDistance() {
        return estimatedRoadDistance;
    }

    public void setEstimatedRoadDistance(RoadDistance estimatedRoadDistance) {
        this.estimatedRoadDistance = estimatedRoadDistance;
    }

    @Embedded
    /*
    // -##----------- OPTION 5 ---------->
    @AttributeOverrides({
        @AttributeOverride(name = "value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE")),
        @AttributeOverride(name = "unit", column = @Column(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
    })
    // <---------- OPTION 5 -----------##-
    */
    public RoadDistance getRealRoadDistance() {
        return realRoadDistance;
    }

    public void setRealRoadDistance(RoadDistance realRoadDistance) {
        this.realRoadDistance = realRoadDistance;
    }

}

// -##----------- OPTION 1 ---------->
/*
@AttributeOverrides({
    @AttributeOverride(name = "estimatedRoadDistance.value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE")),
    @AttributeOverride(name = "estimatedRoadDistance.unit", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID")),
    @AttributeOverride(name = "realRoadDistance.value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE")),
    @AttributeOverride(name = "realRoadDistance.unit", column = @Column(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
})
// <---------- OPTION 1 -----------##-
*/
/*
// -##----------- OPTION 2 ---------->
@AttributeOverrides({
    @AttributeOverride(name = "metricLoader.estimatedRoadDistance.value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE")),
    @AttributeOverride(name = "metricLoader.estimatedRoadDistance.unit", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID")),
    @AttributeOverride(name = "metricLoader.realRoadDistance.value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE")),
    @AttributeOverride(name = "metricLoader.realRoadDistance.unit", column = @Column(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
})
// <---------- OPTION 2 -----------##-
*/
@Entity
@Table(name="ROAD_CONNECTION")
public class RoadConnection {

    private Long id;
    private String pointA;
    private String pointB;
    private RoadMetricLoader metricLoader;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO, generator="ROAD_CONNECTION_SEQ_GENERATOR")
    @SequenceGenerator(name="ROAD_CONNECTION_SEQ_GENERATOR", sequenceName="ROAD_CONNECTION_SEQ")
    @Column(name = "ID")
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @Column(name = "POINT_A", nullable = false)
    public String getPointA() {
        return pointA;
    }

    public void setPointA(String pointA) {
        this.pointA = pointA;
    }

    @Column(name = "POINT_B", nullable = false)
    public String getPointB() {
        return pointB;
    }

    public void setPointB(String pointB) {
        this.pointB = pointB;
    }

    /*
    // -##----------- OPTION 3 ---------->
    @AttributeOverrides({
        @AttributeOverride(name = "estimatedRoadDistance.value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE")),
        @AttributeOverride(name = "estimatedRoadDistance.unit", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID")),
        @AttributeOverride(name = "realRoadDistance.value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE")),
        @AttributeOverride(name = "realRoadDistance.unit", column = @Column(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
    })
    // <---------- OPTION 3 -----------##-
    */
    @Embedded
    public RoadMetricLoader getMetricLoader() {
        return metricLoader;
    }

    public void setMetricLoader(RoadMetricLoader metricLoader) {
        this.metricLoader = metricLoader;
    }

}

2 个答案:

答案 0 :(得分：5)

AttributeOverride用于基本映射。你需要的是AssociationOverride：http://docs.oracle.com/javaee/6/api/javax/persistence/AssociationOverride.html

答案 1 :(得分：1)

由于@Chris建议必须使用AssociatedOverride。如果您按如下方式更改RoadMetricLoader：

public final class RoadMetricLoader {

    private RoadDistance estimatedRoadDistance;
    private RoadDistance realRoadDistance;

    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name = "value", column = @Column(name = "ROAD_ESTIMATED_DISTANCE_VALUE"))
    })
    @AssociationOverrides({  
        @AssociationOverride(name = "unit", joinColumns = @JoinColumn(name = "ROAD_ESTIMATED_DISTANCE_UNIT_ID"))
    })  
    public RoadDistance getEstimatedRoadDistance() {
        return estimatedRoadDistance;
    }

    public void setEstimatedRoadDistance(RoadDistance estimatedRoadDistance) {
        this.estimatedRoadDistance = estimatedRoadDistance;
    }

    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name = "value", column = @Column(name = "ROAD_REAL_DISTANCE_VALUE"))
    })
    @AssociationOverrides({  
        @AssociationOverride(name = "unit", joinColumns = @JoinColumn(name = "ROAD_REAL_DISTANCE_UNIT_ID"))
    })  
    public RoadDistance getRealRoadDistance() {
        return realRoadDistance;
    }

    public void setRealRoadDistance(RoadDistance realRoadDistance) {
        this.realRoadDistance = realRoadDistance;
    }

现在在DB中正确创建了表：

enter image description here

在这种情况下，您还可以删除@AttributeOverrides和@AssociationOverrides，因为每个元素只有一个元素。

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