Autowired objects in aspect are null once code is run

[J Rawlings]

Hi, I am having problems autowiring the entity manager into my Aspect.

When I add a constructor to my Aspect and put a break point on it I can see it hits twice, therefore two objects created. The first time the aspect has an object id of 52. I continue and the breakpoint hits again, this time the Aspect object has an id of 76. My third breakpoint is on a setter for a bean property configured in the application context xml. This refers to the second instance of the object 76 which I can see does have the @PersistenceContext em set correctly. As my test executes and my aspect is launched but the instance used is object 52, this one has null values for the entity manager.

I have copied the stack for each instance.
Aspect object id 52

Thread [main] (Suspended (breakpoint at line 20 in EntityManagerAspectImpl))	
	EntityManagerAspectImpl.<init>() line: 20	
	EntityManagerAspectImpl.ajc$postClinit() line: 1	
	EntityManagerAspectImpl.<clinit>() line: 1	
	J9VMInternals.initializeImpl(Class) line: not available [native method]	
	J9VMInternals.initialize(Class) line: 196	
	NativeConstructorAccessorImpl.newInstance0(Constructor, Object[]) line: not available [native method]	
	NativeConstructorAccessorImpl.newInstance(Object[]) line: 67	
	DelegatingConstructorAccessorImpl.newInstance(Object[]) line: 45	
	Constructor<T>.newInstance(Object...) line: 522	
	BeanUtils.instantiateClass(Constructor, Object[]) line: 100	
	CglibSubclassingInstantiationStrategy(SimpleInstantiationStrategy).instantiate(RootBeanDefinition, String, BeanFactory) line: 61	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).instantiateBean(String, RootBeanDefinition) line: 877	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBeanInstance(String, RootBeanDefinition, Object[]) line: 839	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).doCreateBean(String, RootBeanDefinition, Object[]) line: 440	
	AbstractAutowireCapableBeanFactory$1.run() line: 409	
	AccessController.doPrivileged(PrivilegedAction<T>, AccessControlContext) line: 219	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBean(String, RootBeanDefinition, Object[]) line: 380	
	AbstractBeanFactory$1.getObject() line: 264	
	DefaultListableBeanFactory(DefaultSingletonBeanRegistry).getSingleton(String, ObjectFactory) line: 222	
	DefaultListableBeanFactory(AbstractBeanFactory).doGetBean(String, Class, Object[], boolean) line: 261	
	DefaultListableBeanFactory(AbstractBeanFactory).getBean(String, Class, Object[]) line: 185	
	DefaultListableBeanFactory(AbstractBeanFactory).getBean(String) line: 164	
	DefaultListableBeanFactory.preInstantiateSingletons() line: 429	
	GenericApplicationContext(AbstractApplicationContext).finishBeanFactoryInitialization(ConfigurableListableBeanFactory) line: 728	
	GenericApplicationContext(AbstractApplicationContext).refresh() line: 380	
	NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]	
	NativeMethodAccessorImpl.invoke(Object, Object[]) line: 79	
	DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43	
	Method.invoke(Object, Object...) line: 618	
	GLExtractControlTest(AbstractJpaTests).runBare() line: 230	
	TestResult$1.protect() line: 106	
	TestResult.runProtected(Test, Protectable) line: 124	
	TestResult.run(TestCase) line: 109	
	GLExtractControlTest(TestCase).run(TestResult) line: 120	
	TestSuite.runTest(Test, TestResult) line: 230	
	TestSuite.run(TestResult) line: 225	
	JUnit38ClassRunner.run(RunNotifier) line: 81	
	JUnit4TestClassReference(JUnit4TestReference).run(TestExecution) line: 45	
	TestExecution.run(ITestReference[]) line: 38	
	RemoteTestRunner.runTests(String[], String, TestExecution) line: 460	
	RemoteTestRunner.runTests(TestExecution) line: 673	
	RemoteTestRunner.run() line: 386	
	RemoteTestRunner.main(String[]) line: 196

Aspect object id 76

Thread [main] (Suspended (breakpoint at line 20 in EntityManagerAspectImpl))	
	EntityManagerAspectImpl.<init>() line: 20	
	NativeConstructorAccessorImpl.newInstance0(Constructor, Object[]) line: not available [native method]	
	NativeConstructorAccessorImpl.newInstance(Object[]) line: 67	
	DelegatingConstructorAccessorImpl.newInstance(Object[]) line: 45	
	Constructor<T>.newInstance(Object...) line: 522	
	BeanUtils.instantiateClass(Constructor, Object[]) line: 100	
	CglibSubclassingInstantiationStrategy(SimpleInstantiationStrategy).instantiate(RootBeanDefinition, String, BeanFactory) line: 61	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).instantiateBean(String, RootBeanDefinition) line: 877	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBeanInstance(String, RootBeanDefinition, Object[]) line: 839	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).doCreateBean(String, RootBeanDefinition, Object[]) line: 440	
	AbstractAutowireCapableBeanFactory$1.run() line: 409	
	AccessController.doPrivileged(PrivilegedAction<T>, AccessControlContext) line: 219	
	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBean(String, RootBeanDefinition, Object[]) line: 380	
	AbstractBeanFactory$1.getObject() line: 264	
	DefaultListableBeanFactory(DefaultSingletonBeanRegistry).getSingleton(String, ObjectFactory) line: 222	
	DefaultListableBeanFactory(AbstractBeanFactory).doGetBean(String, Class, Object[], boolean) line: 261	
	DefaultListableBeanFactory(AbstractBeanFactory).getBean(String, Class, Object[]) line: 185	
	DefaultListableBeanFactory(AbstractBeanFactory).getBean(String) line: 164	
	DefaultListableBeanFactory.preInstantiateSingletons() line: 429	
	GenericApplicationContext(AbstractApplicationContext).finishBeanFactoryInitialization(ConfigurableListableBeanFactory) line: 728	
	GenericApplicationContext(AbstractApplicationContext).refresh() line: 380	
	NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]	
	NativeMethodAccessorImpl.invoke(Object, Object[]) line: 79	
	DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43	
	Method.invoke(Object, Object...) line: 618	
	GLExtractControlTest(AbstractJpaTests).runBare() line: 230	
	TestResult$1.protect() line: 106	
	TestResult.runProtected(Test, Protectable) line: 124	
	TestResult.run(TestCase) line: 109	
	GLExtractControlTest(TestCase).run(TestResult) line: 120	
	TestSuite.runTest(Test, TestResult) line: 230	
	TestSuite.run(TestResult) line: 225	
	JUnit38ClassRunner.run(RunNotifier) line: 81	
	JUnit4TestClassReference(JUnit4TestReference).run(TestExecution) line: 45	
	TestExecution.run(ITestReference[]) line: 38	
	RemoteTestRunner.runTests(String[], String, TestExecution) line: 460	
	RemoteTestRunner.runTests(TestExecution) line: 673	
	RemoteTestRunner.run() line: 386	
	RemoteTestRunner.main(String[]) line: 196

I am so close to it all working I'm sure, any help would be fantastic.
Thanks.

[Enrico Pizzi]

I believe you have some misconfiguration...you probably instantiate two different Spring Application Contexts, or have misconfigured AOP and get proxies of proxies, or something like that. You should post your full configuration.

BTW you shouldn't use entity managers directly into an aspect. You should follow the dao pattern and create daos for your database operations, then wire your daos to your services and aspects, but this is just a design suggestion, it has nothing to do with the error.

[J Rawlings]

Ok thanks, I've had another look and cannot for the life of me work out what configuration I have screwed up. I appreciate the help! Let me know if there's anything else I have missed. I am injecting the entity manager so I can call flush and generate an id which is used elsewhere.

Thanks again!

Aspect

@Aspect
@Configurable
public class EntityManagerAspectImpl {

	public EntityManagerAspectImpl() {
		super();
		// TODO Auto-generated constructor stub
	}

	private Logger LOG = Logger.getLogger(this.getClass());

	@PersistenceContext
	private EntityManager em;
	
	protected EntityManagerFactory emf;
	
	@Pointcut("execution(* net.targetgroup.accounts.base.model.GLExtractControl.*(..))")
	public void expireGlExtractKeyAspect() {}

	@After("expireGlExtractKeyAspect()")
	public void flush() {
		LOG.debug("Aspect entity manger flush called");

		em.flush();
		
		LOG.debug("Aspect entity manger flush finished");
	}

	public EntityManagerFactory getEmf() {
		return emf;
	}

	public void setEmf(EntityManagerFactory emf) {
		this.emf = emf;
	}

}

Aspect Spring configuration

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:util="http://www.springframework.org/schema/util"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd">
	
	<context:load-time-weaver aspectj-weaving="on"/>
	

	<aop:aspectj-autoproxy/>

	<bean id="myAspect" class="net.targetgroup.accounts.base.aspect.EntityManagerAspectImpl">
	   <property name="emf" ref="entityManagerFactory" />
	</bean>

</beans>

aop.xml

<aspectj>

    <weaver>
        <!-- only weave classes in our application-specific packages -->
        <include within="net.targetgroup.accounts.base.model.*"/>
    </weaver>

    <aspects>
        <!-- weave in just this aspect -->        
        <aspect name="net.targetgroup.accounts.base.aspect.EntityManagerAspectImpl"/>
    </aspects>

 </aspectj>

Base Spring context

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

	<context:component-scan
		base-package="net.targetgroup.accounts.base.persistence" />
	<context:component-scan
		base-package="net.targetgroup.product.service,net.targetgroup.product.persistence" />
	
	<context:property-placeholder
		location="classpath:application.properties, classpath:guts.properties" />

</beans>

[Enrico Pizzi]

<context:load-time-weaver aspectj-weaving="on"/>


<aop:aspectj-autoproxy/>

Your problem lies in these two lines. The first line activates AspectJ weaving, the second one activates annotated Spring AOP. Thus, your annotated Aspect class gets read two times, and advised classes get both weaved by aspectJ AND proxied by Spring AOP.
You will have to choose only one AOP strategy, either disable Spring AOP by deleting the aop:aspectj-autoproxy line OR disable AspectJ by removing the context:load time weaver element and deleting the aop.xml file (I assume, since you took the pain of configuring full-blown AspectJ, that you'll want to remove Spring AOP).

After that, everything should work as expected.

[ksevindik]

Also @Configurable is unnecessary in this case

[mustangxu]

Is this topic resolved? I met the same problem and I checked my configurations according to the previous reply, but only <aop:aspectj-autoproxy/> is used

Config files:
spring-test.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
  xmlns:jee="http://www.springframework.org/schema/jee" xmlns:aop="http://www.springframework.org/schema/aop"
  xmlns:mvc="http://www.springframework.org/schema/mvc"
  xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">
  <import resource="classpath:spring-common.xml" />
  <import resource="classpath:spring-ldap.xml" />

  <context:annotation-config />
  <context:component-scan base-package="cn.youcredit.thread.auth.service" />
  <context:component-scan base-package="cn.youcredit.thread.auth.dao" />
  <context:component-scan base-package="cn.youcredit.thread.auth.web" />
  <aop:aspectj-autoproxy />
  <mvc:annotation-driven />

  <bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.apache.derby.jdbc.EmbeddedDriver" />
    <property name="url" value="jdbc:derby:thread_auth;create=true" />
  </bean>
  
  <bean id="sessionFactory"
    class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <!-- Inject from dependent projects -->
    <property name="dataSource" ref="dataSource" />
    <property name="annotatedClasses" ref="models" />
    <property name="hibernateProperties">
      <value>
        hibernate.dialect=org.hibernate.dialect.DerbyTenSevenDialect
        hibernate.cache.use_second_level_cache=true
        <!-- hibernate.cache.use_query_cache=true -->
        hibernate.show_sql=true
        hibernate.cache.region.factory_class=org.hibernate.cache.infinispan.InfinispanRegionFactory
        hibernate.hbm2ddl.auto=create
      </value>
    </property>
  </bean>
</beans>

package cn.youcredit.thread.auth.aop;

@Aspect
public class UserAspect {
    @Autowired
    private UserGroupDAO groupDAO;
    @Autowired
    private UserPrivilegeMappingDAO userPrivilegeMappingDAO;
    @Autowired
    private UserPrivilegeGroupMappingDAO userPrivilegeGroupMappingDAO;
}

And I assured that no component scan for cn.youcredit.thread.auth.aop is defined in spring-common.xml nor spring-ldap.xml. In JUnit runtime, all the DAOs are null.

[Enrico Pizzi]

I assured that no component scan for cn.youcredit.thread.auth.aop is defined

and how do you expect Spring to recognize your aspect class as a Spring bean?
context : component-scan scans the classpath searching for @Component and like annotations and registers those classes as Spring beans;
after that, the aop : aspectj-autoproxy tag activates a bean post-processor which scans ALL PREVIOUSLY REGISTERED SPRING BEANS for the @Aspect annotation, and treats those beans as aspects creating and managing the proxies around advised classes accordingly.

If your UserAspect class is not registered as a Spring bean, either through component scan or by directly adding the bean tag to the xml, Spring context will not know of its existence so it will not be considered as an aspect and no aop will be activated.

[mustangxu]

Previously I had @Component in UserAspect, but had the SAME exception:

java.lang.NullPointerException
	at cn.youcredit.thread.auth.aop.UserAspect.buildUserInfos(UserAspect.java:64)
	at cn.youcredit.thread.auth.aop.UserAspect.postProcessUser(UserAspect.java:42)
	at cn.youcredit.thread.auth.dao.UserDAO.getUserByUserame(UserDAO.java:84)
	at cn.youcredit.thread.auth.service.UserService.login(UserService.java:110)
	at cn.youcredit.thread.auth.service.UserService$$FastClassByCGLIB$$dabd4d6.invoke(<generated>)
	at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:689)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
	at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
	at cn.youcredit.thread.auth.service.UserService$$EnhancerByCGLIB$$3d2ce38a.login(<generated>)
	at cn.youcredit.thread.auth.service.UserServiceTest.testLogin(UserServiceTest.java:37)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

And my further question is, if my UserAspect is not recorgnized by Spring without @Component, why I got the same exceptions w/ and w/o @Component? As I understand, I will not get the previous exception w/o @Component at all, since my aspect is not woven.