Question

I have problem in using Persist() method of EntityManager which return NullPointerExpception, here its my code:

@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 comes in line with em.persist(chain)

here its my 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>

and fragment of applicationContext.xml

<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>

trace:

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]

Any clue what am i missing?

Answer 1

The entity manager that is injected is just a proxy. The actual entity manager implementation is injected at run time based on the propagation attribute value in @Transactional annotation associated with the method using the entity manager. So, associate the method saveChain with @Transactional annotation as follows.

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

Strongly advised to go through the documentation of this annotation and set the annotation attributes with values relevant to your use case.

Edit:

The spring DI framework seems to be not picking the setter setEntityManager as the attribute name is em. You may want to rename either the attribute em to entityManager or the setter setEntityManager to setEm or move the @PersistenceContext annotation onto the attribute and try.