Configurable Autowired NullPointerException

[peterwkc]

Hello to all,

I have a GenericServlet class annotated with @Configurable which has field called dao which autowired by spring but it does not get autowired properly rather than throw nullpointerexception.

@Configurable
public class GenericServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
    
	@Autowired
	@Qualifier("genericDaoImpl")
	private GenericDAO dao;
}

@Repository
@Qualifier("genericDaoImpl")
@Transactional(propagation=Propagation.REQUIRED, isolation=Isolation.DEFAULT, rollbackFor={Exception.class, SQLException.class, DataAccessException.class}, timeout=9999)
public class GenericDAOImpl implements GenericDAO {

	@Autowired
	@Qualifier("jdbcTemplate")
	private JdbcTemplate jdbcDao;
}

<?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:p="http://www.springframework.org/schema/p"

	<!-- Enable Spring Application Context -->
	<context:spring-configured />
		
	<!-- Enable @Required @Autowired @PreDestroy @PostConstruct @Resource -->
	<context:annotation-config />
	
	<!-- Scan class file in class path for annotated component -> @Component, @Repository, @Service, and @Controller  -->
	<context:component-scan base-package="com.breeze.bis.core.service.jdbcTemplate" />

	<!-- Enable load time weaving for @Configurable -->
	<context:load-time-weaver aspectj-weaving="autodetect" />
	
	<!-- Alternate method to enable @Autowired -->
	<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>

	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
		<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/vbossdb" />
		<property name="driverClass" value="com.mysql.jdbc.Driver" />
		<property name="user" value="root" />
		<property name="password" value="root" />
	</bean>
	
	<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
		<constructor-arg type="javax.sql.DataSource" ref="dataSource"></constructor-arg>
	</bean>

	<bean id="genericDaoImpl" class="com.breeze.bis.core.service.jdbcTemplate.GenericDAOImpl">
		<property name="jdbcDao" ref="jdbcTemplate"></property>	
	</bean>
		
	<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource"></property> 
	</bean>
	
	<bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> 
		<property name="configLocation" value="WEB-INF/ehcache.xml"></property>
		<property name="shared" value="true"></property>
	</bean>

</beans>

Please let me know what wrong with this configuration.

Thanks.

[peterwkc]

Please help.

[Marten Deinum]

For starters cleanup your configuration file there is a lot of duplication going on..

<?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:p="http://www.springframework.org/schema/p"

	<!-- Enable Spring Application Context -->
	<context:spring-configured />
		
	<!-- Enable @Required @Autowired @PreDestroy @PostConstruct @Resource -->
	<context:annotation-config /> <!-- Already implied by component-scan -->
	
	<!-- Scan class file in class path for annotated component -> @Component, @Repository, @Service, and @Controller  -->
	<context:component-scan base-package="com.breeze.bis.core.service.jdbcTemplate" />

	<!-- Enable load time weaving for @Configurable -->
	<context:load-time-weaver aspectj-weaving="autodetect" />
	
	<!-- Alternate method to enable @Autowired -->
	<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
 <!-- Already implied by component-scan AND annotation-config -->

	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
		<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/vbossdb" />
		<property name="driverClass" value="com.mysql.jdbc.Driver" />
		<property name="user" value="root" />
		<property name="password" value="root" />
	</bean>
	
	<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
		<constructor-arg type="javax.sql.DataSource" ref="dataSource"></constructor-arg>
	</bean>

	<bean id="genericDaoImpl" class="com.breeze.bis.core.service.jdbcTemplate.GenericDAOImpl">
		<property name="jdbcDao" ref="jdbcTemplate"></property>	
	</bean> <!-- Already using Component-Scan duplicate bean definition -->
		
	<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource"></property> 
	</bean>
	
	<bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> 
		<property name="configLocation" value="WEB-INF/ehcache.xml"></property>
		<property name="shared" value="true"></property>
	</bean>

</beans>

This config must be loaded by the ContextLoaderListener for @Configurable in servlets to work, also if it works depends on y our container it might be that it doesn't work and that it required additional configuration. For more information I suggest the reference guide chapter on loadtime weavnig in containers.

[peterwkc]

Yes, I had clean up the config. The Config was loaded by ContextLoaderListener. I thought the @configurable is relate to spring and not container problem. I had enable logging and how to diagnose the problem which DI(Configurable, Autowired) not working. No stacktrace or log.

I using TomcatInstrumentableClassLoader which put inside the Tomcat\lib directory and context.xml in Meta-INF Folder.

15:49:12,351 INFO DefaultContextLoadTimeWeaver:89 - Using a reflective load-time weaver for class loader: org.springframework.instrument.classloading.tomcat .TomcatInstrumentableClassLoader
15:49:13,033 INFO DefaultListableBeanFactory:577 - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultL istableBeanFactory@1df304: defining beans [org.springframework.context.config.internalBeanCon figurerAspect,genericDAOImpl,org.springframework.c ontext.annotation.internalConfigurationAnnotationP rocessor,org.springframework.context.annotation.in ternalAutowiredAnnotationProcessor,org.springframe work.context.annotation.internalRequiredAnnotation Processor,org.springframework.context.annotation.i nternalCommonAnnotationProcessor,org.springframewo rk.context.weaving.AspectJWeavingEnabler#0,loadTim eWeaver,org.springframework.aop.config.internalAut oProxyCreator,org.springframework.transaction.anno tation.AnnotationTransactionAttributeSource#0,org. springframework.transaction.interceptor.Transactio nInterceptor#0,org.springframework.transaction.con fig.internalTransactionAdvisor,org.springframework .cache.annotation.AnnotationCacheOperationSource#0 ,org.springframework.cache.interceptor.CacheInterc eptor#0,org.springframework.cache.config.internalC acheAdvisor,dataSource,jdbcTemplate,transactionMan ager,ehcache,cacheManager,org.springframework.cont ext.annotation.ConfigurationClassPostProcessor.imp ortAwareProcessor]; root of factory hierarchy
15:49:13,338 INFO MLog:80 - MLog clients using log4j logging.

<Context path="/myWebApp" docBase="/my/webApp/location">
<Loader loaderClass="org.springframework.instrument.classl oading.tomcat.TomcatInstrumentableClassLoader"
useSystemClassLoaderAsParent="false"/>
</Context>

I change the Autowired using setter in GenericServlet and the setter is not even get called.

[Marten Deinum]

As mentioned read the reference guide some containers need additional configuration (Tomcat for instance) to make loadtimeweaving work.

[peterwkc]

As mentioned read the reference guide some containers need additional configuration (Tomcat for instance) to make loadtimeweaving work.

I using TomcatInstrumentableClassLoader (Spring-Instrument-Tomcat-3.1.2.jar) which put inside the Tomcat\lib directory and context.xml in Meta-INF Folder.

<Context path="/myWebApp" docBase="/my/webApp/location">
<Loader loaderClass="org.springframework.instrument.classl oading.tomcat.TomcatInstrumentableClassLoader"/>
</Context>

What are the additional configuration for load time weavering since the servlet can be loaded by the TomcatInstrumentableClassLoader.