春天Hibernate的JPA EntityManager.Persist（）NullPointerException異常

Question

我在使用的EntityManagerPersist()方法問題，其返回NullPointerExpception，這裏的我的代碼：

@Repository("chainDao") 
public class ChainDaoImpl implements ChainDao{ 

    private EntityManager em; 

    @PersistenceContext(unitName="hibernatePersistenceUnit") 
    public void setEntityManager(EntityManager em) { 
    this.em = em; 
    } 

    public int saveChain(Chain chain) { 
     em.persist(chain); 
     return 0; 
    } 
} 

Expcetion配備符合em.persist(chain)

這裏的我persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0"> 

<persistence-unit name="hibernatePersistenceUnit" transaction-type="RESOURCE_LOCAL"> 
<properties> 
<property name="hibernate.hbm2ddl.auto" value="none" /> 
</properties> 
</persistence-unit> 

</persistence> 

和的片段3210

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" 
destroy-method="close" 
p:driverClass="${database.driver}" 
p:jdbcUrl="${database.url}" 
p:user="${database.user}" 
p:password="${database.password}" 
p:acquireIncrement="5" 
p:idleConnectionTestPeriod="60" 
p:maxPoolSize="100" 
p:maxStatements="50" 
p:minPoolSize="10" /> 
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" > 
<property name="persistenceXmlLocation" value="classpath*:META-INF/persistence.xml"></property> 
<property name="persistenceUnitName" value="hibernatePersistenceUnit" /> 
<property name="dataSource" ref="dataSource"/> 
<property name="jpaVendorAdapter"> 
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" > 
<property name="showSql" value="true"/> 
</bean> 
</property> 
</bean> 

跟蹤：

java.lang.NullPointerException: null 
    at pl.postgresql.jpa.dao.ChainDaoImpl.saveCaChain(ChainDaoImpl.java:33) ~[CaChainDaoImpl.class:na] 
    at pl.postgresql.jpa.service.StorageServiceImpl.addChain(StorageServiceImpl.java:50) ~[StorageServiceImpl.class:na] 
    at pl.camel.jms.service.InputDatabaseServiceImpl.inputChain(InputDatabaseServiceImpl.java:48) ~[InputDatabaseServiceImpl.class:na] 
    at pl.camel.jms.connector.EndpointHelper.run(EndpointHelper.java:49) ~[EndpointHelper.class:na] 
    at pl.ws.spring.endpoint.CaEndpoint.getCAChain(CaEndpoint.java:63) ~[CaEndpoint.class:na] 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_09] 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_09] 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_09] 
    at java.lang.reflect.Method.invoke(Method.java:601) ~[na:1.7.0_09] 
    at org.springframework.ws.server.endpoint.MethodEndpoint.invoke(MethodEndpoint.java:134) ~[spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.server.endpoint.adapter.DefaultMethodEndpointAdapter.invokeInternal(DefaultMethodEndpointAdapter.java:229) ~[spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.server.endpoint.adapter.AbstractMethodEndpointAdapter.invoke(AbstractMethodEndpointAdapter.java:53) ~[spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.server.MessageDispatcher.dispatch(MessageDispatcher.java:233) [spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.server.MessageDispatcher.receive(MessageDispatcher.java:173) [spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.transport.support.WebServiceMessageReceiverObjectSupport.handleConnection(WebServiceMessageReceiverObjectSupport.java:88) [spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.transport.http.WebServiceMessageReceiverHandlerAdapter.handle(WebServiceMessageReceiverHandlerAdapter.java:59) [spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.ws.transport.http.MessageDispatcherServlet.doService(MessageDispatcherServlet.java:221) [spring-ws-core-2.1.1.RELEASE.jar:na] 
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) [spring-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE] 
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) [spring-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE] 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) [servlet-api.jar:na] 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) [servlet-api.jar:na] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) [catalina.jar:7.0.30.A] 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) [catalina.jar:7.0.30.A] 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002) [tomcat-coyote.jar:7.0.30.A] 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) [tomcat-coyote.jar:7.0.30.A] 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) [tomcat-coyote.jar:7.0.30.A] 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [na:1.7.0_09] 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [na:1.7.0_09] 
    at java.lang.Thread.run(Thread.java:722) [na:1.7.0_09] 

任何線索我失去了什麼？

Answer 1

注入的實體管理器只是一個代理。基於與使用實體管理器的方法關聯的@Transactional註釋中的傳播屬性值，在運行時注入實際的實體管理器實現。因此，將方法saveChain與@Transactional註釋關聯如下。

@Transactional 
public int saveChain(Chain chain) { 
    em.persist(chain); 
    return 0; 
} 

強烈建議您仔細閱讀此註釋的文檔，並使用與您的用例相關的值設置註釋屬性。

編輯：

彈簧DI框架似乎沒有采摘的setter setEntityManager作爲屬性名稱是em。您可能想要將屬性em更改爲entityManager或將設置器setEntityManager更改爲setEm，或者將@PersistenceContext註釋移至該屬性上並嘗試。