6

我需要下一个问题的帮助，这似乎与这个问题非常相似。但是，建议的解决方案不适用于我的情况。我有标记为@Embbedable 的RoadDistance 类和标记为@Embbedable 的RoadMetricLoader 类，它包含两个RoadDistante 类型的属性。还有类 RoadConnection，它是一个实体，包括 RoadmetricLoader 类型的属性。我没有成功为 RoadDistance 类覆盖 RoadMetricLoader 的属性 (@AttributeOverride)（我没有在 ROAD_CONNECTION 表中获得字段 ROAD_ESTIMATED_DISTANCE_VALUE、ROAD_ESTIMATED_DISTANCE_UNIT_ID、ROAD_REAL_DISTANCE_VALUE 和 ROAD_REAL_DISTANCE_UNIT_ID）

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

我尝试了不同的选项，但它们都不起作用。我在代码中的注释块中显示了所有选项，您可以在下面看到。当未注释一个选项时，请保留其他选项。这些是我在每种情况下得到的结果：

选项 1：它不返回任何错误，但在 ROAD_CONNECTION 表中我只得到两个字段：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（请参阅官方文档示例 2，以及上面已经指出的链接），但我收到下一个错误

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;
    }

}
4

2 回答 2

5

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

于 2013-01-20T04:10:00.993 回答
1

正如@Chris 建议的，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;
    }

现在该表已在数据库中正确创建：

在此处输入图像描述

在这种情况下，您也可以去掉@AttributeOverrides 和@AssociationOverrides，因为每个元素只有一个元素。

于 2013-01-20T13:11:10.200 回答