Spring Data JPA：如何修复CrudRepository的findById方法中的NullPointerException？

Question

在从MSSQL数据库中选择数据时，istill无法解决CrudRepository的问题。

存储库看起来像：

@Repository
public interface MarketInfoRepository extends CrudRepository<MarketInfoEntity, MarketInfoEntityPK> {

   // MarketInfoEntity findById(Integer id);
     MarketInfoEntity findById(MarketInfoEntityPK marketInfoEntityPK);

}

MarketInfoEntity实体为：

@Entity
@Table(name = "MarketInfo", schema = "dbo", catalog = "")
@IdClass(MarketInfoEntityPK.class)
public class MarketInfoEntity {
    private int id;
    /*other fields*/

    @Basic
    @Column(name = "id")
    public int getId() {
        return id;
    }

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


@Id
@Column(name = "Asset_ID")
public double getAssetId() {
    return assetId;
}

public void setAssetId(double assetId) {
    this.assetId = assetId;
}

@Id
@Column(name = "TSSection_ID")
public double getTsSectionId() {
    return tsSectionId;
}

public void setTsSectionId(double tsSectionId) {
    this.tsSectionId = tsSectionId;
}


    /*equals and hashcode*/
}

运行测试时：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {OlmeCapConfig.class} , loader = AnnotationConfigContextLoader.class)
public class MarketInfoCapRepositoryTest {


    @Autowired
    MarketInfoCapRepository marketInfoCapRepository;


    @Test
    public void findById() throws Exception {

        try {
            marketInfoCapRepository.findById(82524);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

下一个堆栈跟踪如下：

java.lang.NullPointerException
    at org.hibernate.internal.util.StringHelper.root(StringHelper.java:379)
    at org.hibernate.persister.entity.AbstractEntityPersister.getSubclassPropertyTableNumber(AbstractEntityPersister.java:1884)
    at org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:46)
    at org.hibernate.persister.entity.AbstractEntityPersister.toColumns(AbstractEntityPersister.java:1827)
    at org.hibernate.hql.internal.ast.tree.FromElement.getIdentityColumns(FromElement.java:354)
    at org.hibernate.hql.internal.ast.tree.IdentNode.resolveAsAlias(IdentNode.java:198)
    at org.hibernate.hql.internal.ast.tree.IdentNode.resolve(IdentNode.java:124)
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:109)
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:104)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.resolve(HqlSqlWalker.java:1013)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.propertyRef(HqlSqlBaseWalker.java:1165)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2287)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2228)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1499)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:583)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:311)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:259)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:261)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:141)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:115)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153)
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:545)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:654)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:3307)
    at org.hibernate.query.criteria.internal.CriteriaQueryImpl$1.buildCompiledQuery(CriteriaQueryImpl.java:318)
    at org.hibernate.query.criteria.internal.compile.CriteriaCompiler.compile(CriteriaCompiler.java:127)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:3600)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:203)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:347)
    at com.sun.proxy.$Proxy44.createQuery(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:298)
    at com.sun.proxy.$Proxy44.createQuery(Unknown Source)
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.createQuery(PartTreeJpaQuery.java:198)
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.createQuery(PartTreeJpaQuery.java:148)
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.doCreateQuery(PartTreeJpaQuery.java:79)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.createQuery(AbstractJpaQuery.java:190)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$SingleEntityExecution.doExecute(JpaQueryExecution.java:206)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:85)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:116)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:106)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:483)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:61)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    at com.sun.proxy.$Proxy64.findById(Unknown Source)
    at com.pivotal.olme.jpa.dao.cap.MarketInfoCapRepositoryTest.findById(MarketInfoCapRepositoryTest.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

你能帮我修一下这个NPE吗？

附笔。

>

可能问题出在未知源代码中（查看堆栈跟踪）

另外，我还有一个方法，它使用相同的数据源扩展了CrudRepository，并且运行良好。

再次为昨天发布的stacktrace错误的帖子感到抱歉。

Answer 1

您的代码存在多个问题。

当CrudRepository提供findOne方法时，为什么要使用自定义findById方法。实体的Id类不是整数，而是MarketinFontityPK，因此findById应该接受它（findOne会自动使用它）。

此外，您没有任何带有Id注释的字段。