【发布时间】：2011-01-03 08:57:18
【问题描述】：
我在使用 open jpa 时在控制台上出现以下错误。可能的原因是什么？我无法发布代码，因为它违反了我的公司政策。
[12/31/10 14:54:13:279 GMT+05:30] 00000063 MetaData W CWWJP9991W: openjpa.MetaData: Warn: OpenJPA cannot map field "abc.xyz" efficiently. It is of an unsupported type. The field value will be serialized to a BLOB by default.
[12/31/10 14:54:13:295 GMT+05:30] 00000063 MetaData W CWWJP9991W: openjpa.MetaData: Warn: The class "pqr.xyz" listed in the openjpa.MetaDataFactory configuration property could not be loaded; ignoring.
[12/31/10 14:54:13:295 GMT+05:30] 00000063 MetaData W CWWJP9991W: openjpa.MetaData: Warn: OpenJPA cannot map field "pqr.xyz" efficiently. It is of an unsupported type. The field value will be serialized to a BLOB by default.
Failed to create Bundle in DB:
<openjpa-1.2.2-SNAPSHOT-r422266:778978M-OPENJPA-975 fatal user error> org.apache.openjpa.persistence.ArgumentException: Field "abc.xyz" cannot declare that it is mapped by another field. Its mapping strategy (org.apache.openjpa.jdbc.meta.strats.HandlerFieldStrategy) does not support mapping by another field.
at org.apache.openjpa.jdbc.meta.strats.AbstractFieldStrategy.assertNotMappedBy(AbstractFieldStrategy.java:59)
at org.apache.openjpa.jdbc.meta.strats.HandlerFieldStrategy.map(HandlerFieldStrategy.java:71)
at org.apache.openjpa.jdbc.meta.FieldMapping.setStrategy(FieldMapping.java:121)
at org.apache.openjpa.jdbc.meta.RuntimeStrategyInstaller.installStrategy(RuntimeStrategyInstaller.java:80)
at org.apache.openjpa.jdbc.meta.FieldMapping.resolveMapping(FieldMapping.java:454)
at org.apache.openjpa.jdbc.meta.FieldMapping.resolve(FieldMapping.java:419)
at org.apache.openjpa.jdbc.meta.ClassMapping.resolveNonRelationMappings(ClassMapping.java:879)
at org.apache.openjpa.jdbc.meta.MappingRepository.prepareMapping(MappingRepository.java:339)
at org.apache.openjpa.meta.MetaDataRepository.preMapping(MetaDataRepository.java:662)
at org.apache.openjpa.meta.MetaDataRepository.resolve(MetaDataRepository.java:549)
at org.apache.openjpa.meta.MetaDataRepository.getMetaData(MetaDataRepository.java:308)
at org.apache.openjpa.meta.MetaDataRepository.getMetaData(MetaDataRepository.java:363)
at org.apache.openjpa.kernel.QueryImpl.classForName(QueryImpl.java:1569)
at org.apache.openjpa.kernel.ExpressionStoreQuery$1.classForName(ExpressionStoreQuery.java:108)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getClassMetaData(JPQLExpressionBuilder.java:168)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.resolveClassMetaData(JPQLExpressionBuilder.java:139)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateMetaData(JPQLExpressionBuilder.java:225)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateMetaData(JPQLExpressionBuilder.java:195)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateType(JPQLExpressionBuilder.java:188)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.access$600(JPQLExpressionBuilder.java:69)
at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder$ParsedJPQL.populate(JPQLExpressionBuilder.java:1756)
at org.apache.openjpa.kernel.jpql.JPQLParser.populate(JPQLParser.java:56)
at org.apache.openjpa.kernel.ExpressionStoreQuery.populateFromCompilation(ExpressionStoreQuery.java:153)
at org.apache.openjpa.kernel.QueryImpl.newCompilation(QueryImpl.java:658)
at org.apache.openjpa.kernel.QueryImpl.compilationFromCache(QueryImpl.java:639)
at org.apache.openjpa.kernel.QueryImpl.compileForCompilation(QueryImpl.java:605)
at org.apache.openjpa.kernel.QueryImpl.compileForExecutor(QueryImpl.java:667)
at org.apache.openjpa.kernel.QueryImpl.compile(QueryImpl.java:574)
at com.xyz.ws.persistence.EntityManagerImpl.createNamedQuery(EntityManagerImpl.java:105)
at com.xyz.ws.persistence.EntityManagerImpl.createNamedQuery(EntityManagerImpl.java:37)
at com.xyz.ws.jpa.management.JPATxEmInvocation.createNamedQuery(JPATxEmInvocation.java:116)
at com.xyz.ws.jpa.management.JPAEntityManager.createNamedQuery(JPAEntityManager.java:302)
【问题讨论】：
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我首先要弄清楚为什么 pqr.xyz 无法加载。也许您的环境缺少一些依赖项；也许类名在某处拼写错误；也许运行 OpenJPA 的类加载环境不合适。