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  • Weird @Autowired Behavior of @Configuration Class, which causes NPE

    Hi,

    I am running into a weird behavior of autowiring a @Configuration class inside another @Configuration class when there is a BeanFactoryPostProcessor in my application.

    If I run MyAppTests.java as it is, an NPE will happen on line BizClient client = bizClientConfig.bizClient() inside MyAppConfig.java.

    However, if I commented out line Map<String, Object> map = beanFactory.getBeansWithAnnotation(Configuration.c lass) in ConfigurationBeanFactoryPostProcessor.java then the NPE goes away.

    I don't understand why calling beanFactory.getBeansWithAnnotation() causes NPE. Is this a bug or I am missing something?

    This problem happens in both Spring version 3.0.5 as well as 3.0.6.

    The complete project is attached.

    Any ideas?

    Here is the code.

    Code:
    @Configuration
    public class MyAppConfig {
    	
    	@Autowired
    	private BizClientConfig bizClientConfig;
    	
    	@Bean
    	public MyApp myApp() {
    		BizClient client = bizClientConfig.bizClient();
    		
    		return new MyApp(client);
    	}
    }
    Code:
    @Configuration
    public class BizClientConfig {
    	
    	@Bean
    	public BizClient bizClient() {
    		return new BizClientImpl("no name");
    	}
    
    }
    Code:
    public class ConfigurationBeanFactoryPostProcessor implements
    		BeanFactoryPostProcessor {
    
    	public void postProcessBeanFactory(
    			ConfigurableListableBeanFactory beanFactory) throws BeansException {
    
    		Map<String, Object> map = beanFactory.getBeansWithAnnotation(Configuration.class); 
    	}
    }
    app-context.xml
    Code:
    <?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"
    	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    
    	<description>Example configuration to get you started.</description>
    
    	<bean class="org.my.test.ConfigurationBeanFactoryPostProcessor" />
    	
    	<context:component-scan base-package="org.my.test" />
    
    </beans>
    Test class:
    Code:
    @ContextConfiguration(locations="classpath:/META-INF/spring/app-context.xml")
    @RunWith(SpringJUnit4ClassRunner.class)
    public class MyAppTests {
    	
    	@Autowired
    	private MyApp myapp;
    
    	@Test
    	public void testMyApp() throws Exception {
    		System.out.println("Spring version: " + SpringVersion.getVersion());
    		assertNotNull(myapp);
    	}
    	
    }
    stack trace:

    Code:
    java.lang.IllegalStateException: Failed to load ApplicationContext
    	at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:308)
    	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109)
    	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75)
    	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:321)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:211)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
    	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    	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:236)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
    	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)
    Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myApp' defined in class path resource [org/my/test/MyAppConfig.class]: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public org.my.test.MyApp org.my.test.MyAppConfig.myApp()] threw exception; nested exception is java.lang.NullPointerException
    	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:581)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:983)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:879)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
    	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
    	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:84)
    	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:1)
    	at org.springframework.test.context.TestContext.loadApplicationContext(TestContext.java:280)
    	at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:304)
    	... 24 more
    Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public org.my.test.MyApp org.my.test.MyAppConfig.myApp()] threw exception; nested exception is java.lang.NullPointerException
    	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:157)
    	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:570)
    	... 39 more
    Caused by: java.lang.NullPointerException
    	at org.my.test.MyAppConfig.myApp(MyAppConfig.java:17)
    	at org.my.test.MyAppConfig$$EnhancerByCGLIB$$66367b2c.CGLIB$myApp$0(<generated>)
    	at org.my.test.MyAppConfig$$EnhancerByCGLIB$$66367b2c$$FastClassByCGLIB$$123ec952.invoke(<generated>)
    	at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:215)
    	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:210)
    	at org.my.test.MyAppConfig$$EnhancerByCGLIB$$66367b2c.myApp(<generated>)
    	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.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:145)
    	... 40 more

  • #2
    This is kind of disappointing that I haven't gotten any reply from any Spring experts.

    My company is evaluating the Java-configuration support in Spring 3 and with this problem, we are not able to move forward.

    I spent a little more time looking into this but haven't have any luck yet. I tried changing the autowired on member variable to a setter method (see below) in MyAppConfig.java and I can definitely confirmed that the setter method was not called.

    @Autowired
    public void setBizClientConfig(BizClientConfig bizClientConfig) {
    this.bizClientConfig = bizClientConfig;
    }

    This seems like a bug to me.

    Can some Spring expert from VMWare confirm this? or Should I go ahead and create a jira ticket for this issue?

    Comment


    • #3
      NEVER MIND. I figured out the problem!!!

      It is my misunderstanding of method org.springframework.beans.factory.ListableBeanFact ory.getBeansWithAnnotation().

      Basically the above method will return a map of bean names and their corresponding bean instances as values, which means that those beans will get instantiated before AutowiredAnnotationBeanPostProcessor.java gets a chance to perform its autowiring magic. That's why bizClientConfig is null when myApp method is called.
      Last edited by hluu; Nov 9th, 2011, 12:48 PM.

      Comment

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