Session scoped beans with constructor args

[Oliver Gierke]

Hello again,

I'm trying to get my AuthenticationManager being session scoped. I try to confiugre it as follows:

<bean id="AuthenticationManager" class="....AuthenticationManagerImpl" scope="session">
	<constructor-arg ref="UserDAO" />
	<aop:scoped-proxy />		
</bean>

and get

11:13:57,352 ERROR ContextLoader:205 - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'AuthenticationManager': Initialization of bean failed; nested exception is null
Caused by: 
java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
at net.sf.cglib.proxy.Enhancer.emitConstructors(Enhancer.java:718)
	at net.sf.cglib.proxy.Enhancer.generateClass(Enhancer.java:499)
	at net.sf.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)
	at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
	at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:216)
	at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:377)
	at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:285)
	at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:195)
	at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:150)
	at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:72)
	at org.springframework.aop.scope.ScopedProxyFactoryBean.setBeanFactory(ScopedProxyFactoryBean.java:87)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:866)
...

Seems like the Proxy doesn't forward the constructor argument. I rarely would like to switch to SetterInjection.

Any Ideas?

Regards
Ollie

[Jörg Heinicke]

Seems like the Proxy doesn't forward the constructor argument. I rarely would like to switch to SetterInjection.

The scoped proxies are indeed CGLib proxies and don't support constructor arguments. I don't know about <aop:scoped-proxy/>, but with my setup it is possible to specify a property "proxyTargetClass" and set it to false, so that JDK dynamic proxies are generated and so constructor arguments are supported.

The config should look similar to the following:

  <bean id="AuthenticationManager" scope="singleton"
        class="org.springframework.aop.scope.ScopedProxyFactoryBean">
    <property name="proxyTargetClass" value="false"/>
    <property name="targetBeanName" value="AuthenticationManagerTarget"/>
  </bean>

  <bean id="AuthenticationManagerTarget" scope="session"
        class="....AuthenticationManagerImpl"/>

There was a bug in former RC and milestone versions, where proxyTargetClass was disregarded, but it shall be fixed since RC 2: issue SPR-2021. I haven't tested it yet.

As I said I don't know if <aop:scoped-proxy/> supports this feature as well, maybe it is as easy as specifying it as property to it as well.

Jörg

[Oliver Gierke]

Thanks a lot, that seems to solve my problem. I do not depend on <aop:scoped-proxy />, your configuration works well.

Regards,
Ollie