當初始化Spring數據存儲庫時出現NullPointerException異常

Question

我有Spring，Hibernate/JPA和Spring Data的webapp。我爲一些實體創建了擴展JpaRepository的存儲庫，並且對於像.save（T）或saveAndFlush，findAll這樣的默認方法，即使使用findBy，如果某些字段名稱如id（findById）或findByRole那樣簡單 - 其中Role是枚舉或者findByActive，其中active是給定實體中的布爾字段。 但是，當我嘗試對複雜對象的域進行同樣的操作時，我陷入了麻煩。我有名爲Person的天賦。 Person have field

private User manager;

與獲得者/設定者。當我試圖把這個PersonRepository，如：

public interface PersonRepository extends JpaRepository<Person, Long> { 

    List<Person> findByManager(User manager); 
} 

我的應用程序部署過程中有一個例外：

Context initialization failed 
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'PersonRepository': Invocation of init method failed; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1512) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:610) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479) 
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389) 
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294) 
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112) 
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4973) 
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5467) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) 
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) 
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:632) 
    at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1740) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301) 
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819) 
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801) 
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:618) 
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:565) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301) 
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819) 
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801) 
    at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1487) 
    at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:97) 
    at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1328) 
    at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1420) 
    at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:848) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:322) 
    at sun.rmi.transport.Transport$1.run(Transport.java:177) 
    at sun.rmi.transport.Transport$1.run(Transport.java:174) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at sun.rmi.transport.Transport.serviceCall(Transport.java:173) 
    at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:556) 
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:811) 
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:670) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 
    at java.lang.Thread.run(Thread.java:744) 
Caused by: java.lang.NullPointerException 
    at org.springframework.data.jpa.repository.query.QueryUtils.getOrCreateJoin(QueryUtils.java:522) 
    at org.springframework.data.jpa.repository.query.QueryUtils.toExpressionRecursively(QueryUtils.java:459) 
    at org.springframework.data.jpa.repository.query.JpaQueryCreator$PredicateBuilder.build(JpaQueryCreator.java:199) 
    at org.springframework.data.jpa.repository.query.JpaQueryCreator.toPredicate(JpaQueryCreator.java:146) 
    at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:86) 
    at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:44) 
    at org.springframework.data.repository.query.parser.AbstractQueryCreator.createCriteria(AbstractQueryCreator.java:109) 
    at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:88) 
    at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:73) 
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.<init>(PartTreeJpaQuery.java:98) 
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$CountQueryPreparer.<init>(PartTreeJpaQuery.java:186) 
    at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:60) 
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:91) 
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:162) 
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:69) 
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:304) 
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:161) 
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.initAndReturn(RepositoryFactoryBeanSupport.java:224) 
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:210) 
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:84) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1571) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1509) 
    ... 55 more 

我想即使是這樣的：findByManagerId(Lond id);和一些其他的組合，都是一樣的。有任何想法嗎？從我的pom.xml

importanp部分：

<dependency> 
      <groupId>org.hibernate</groupId> 
      <artifactId>hibernate-entitymanager</artifactId> 
      <version>3.5.1-Final</version> 
     </dependency> 
    <dependency> 
      <groupId>org.hibernate.javax.persistence</groupId> 
      <artifactId>hibernate-jpa-2.0-api</artifactId> 
      <version>1.0.1.Final</version> 
     </dependency> 
     <dependency> 
      <groupId>org.springframework.data</groupId> 
      <artifactId>spring-data-jpa</artifactId> 
      <version>1.5.1.RELEASE</version> 
     </dependency> 

Answer 1

這解決了我的問題（STIL不知道什麼是應用程序初始化期間NullPointerException異常的東西），但無論如何，這有助於（在我的PersonRepository）：

@Query("SELECT person from Person person where person.manager=:manager") 
public List<Person> findByManager(@Param("manager")User manager); 

救了我的一天......我仍然認爲應該沒有查詢和NPE看起來像一個錯誤。多謝你們！

Answer 2

這並沒有直接回答，爲什麼你得到空指針，但你可以嘗試使該查詢，而不是一個自定義實現。有關如何做到這一點的信息，請閱讀this documentation的1.3。