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我正在使用 JPA 从 Oracle XMLType 列中检索数据。我创建了一个定制器：

@Override
public void customize(final ClassDescriptor descriptor) throws Exception {
    descriptor.removeMappingForAttributeName("content");
    DirectToXMLTypeMapping mapping = new DirectToXMLTypeMapping();
    mapping.setAttributeName("content"); //name of the atribute on the Entity Bean
    mapping.setFieldName("CONTENT"); //name of the data base column
    mapping.getField().setColumnDefinition("XMLTYPE");
    descriptor.addMapping(mapping);
}

我的实体类中的列是：

@Basic(optional = false)
@NotNull
@Lob
//@Column(name = "CONTENT", columnDefinition="XMLTYPE")    
private String content;

但是，当我运行我的程序时，我收到错误“ java.lang.ClassCastException: oracle.xdb.XMLType cannot be cast to java.lang.String at entities.Sqdocument._persistence_set(Sqdocument.java) at org.eclipse.persistence.internal.descriptors.PersistenceObjectAttributeAccessor.setAttributeValueInObject(PersistenceObjectAttributeAccessor.java:46) at org.eclipse.persistence.mappings.DatabaseMapping.setAttributeValueInObject(DatabaseMapping.java:1532) at org.eclipse.persistence.mappings.DatabaseMapping.readFromRowIntoObject(DatabaseMapping.java:1423) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildAttributesIntoObject(ObjectBuilder.java:448) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:803) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:607) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:564) at org.eclipse.persistence.queries.ObjectLevelReadQuery.buildObject(ObjectLevelReadQuery.java:777) at org.eclipse.persistence.queries.ReadObjectQuery.executeObjectLevelReadQuery(ReadObjectQuery.java:462) at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1150) at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:852) at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1109) at org.eclipse.persistence.queries.ReadObjectQuery.execute(ReadObjectQuery.java:421) at org.eclipse.persistence.internal.sessions.AbstractSession.internalExecuteQuery(AbstractSession.java:2946) at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1602) at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1584) at org.eclipse.persistence.internal.indirection.NoIndirectionPolicy.valueFromQuery(NoIndirectionPolicy.java:323) at org.eclipse.persistence.mappings.ForeignReferenceMapping.valueFromRowInternal(ForeignReferenceMapping.java:2135) at org.eclipse.persistence.mappings.OneToOneMapping.valueFromRowInternal(OneToOneMapping.java:1716) at org.eclipse.persistence.mappings.ForeignReferenceMapping.valueFromRow(ForeignReferenceMapping.java:2024) at org.eclipse.persistence.mappings.ForeignReferenceMapping.readFromRowIntoObject(ForeignReferenceMapping.java:1369) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildAttributesIntoObject(ObjectBuilder.java:448) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:803) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildWorkingCopyCloneNormally(ObjectBuilder.java:719) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObjectInUnitOfWork(ObjectBuilder.java:672) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:605) at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:564) at org.eclipse.persistence.queries.ObjectLevelReadQuery.buildObject(ObjectLevelReadQuery.java:777) at org.eclipse.persistence.queries.ReadAllQuery.registerResultInUnitOfWork(ReadAllQuery.java:783) at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:434) at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1150) at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:852) at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1109) at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:393) ”可能是什么问题？谢谢。

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1 回答 1

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Eclipselink 正在成功检索 XML 类型。问题是 XMLType 不是 String 的实例，因此无法自动转换。

您需要编写一个转换器来在 XMLType 和 String 之间进行转换。如果您想以任何方式更改数据，您还需要编写从 String 到 XMLType 的转换器的另一端。

查看Conversions and Converters以获取编写转换器的帮助。

于 2013-03-15T16:54:10.530 回答