Autowiring request scoped beans into application scoped beans

Question

Is it possible to autowire a request scoped bean into an application scoped bean. i.e

I have a class RequestScopedBean:

class RequestScopedBean {
   ....
   ....
   ....
}

and a class Application scoped bean in which the request scoped bean is autowired.

class ApplicationScopedBean {
   @Autowire
   private RequestScopedBean requestScopedBean;
   ....
   ....
   ....
}

and the spring-config xml is as follows:

<?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:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="
              http://www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/util  http://www.springframework.org/schema/util/spring-util-3.0.xsd
">
<bean id="applicationScopedBeans" class="ApplicationScopedBean" />
<bean id="requestScopedBean" class="RequestScopedBean" scope="request">  
</bean>
</beans>

when I try to run this application the bean creation of applicationScopedBean fails with the following error:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ApplicationScopedBean': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not       autowire field: private RequestScopedBean requestScopedBean; nested exception is java.lang.IllegalStateException: No Scope registered for scope 'request'
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:288)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:312)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1075)
    at com.amazon.coral.reflect.instantiate.SpringInstantiatorFactory$1.newInstance(SpringInstantiatorFactory.java:168)
    ... 19 more

Answer 1

You have to mark your requestScopedBean as a scoped proxy also, this way Spring will inject in a proxy for requestScopedBean and in the background manage the scope appropriately.

<bean id="requestScopedBean" class="RequestScopedBean" scope="request">  
    <aop:scoped-proxy/>
</bean>

More here

Answer 2

The exception above suggests that you have not correctly configured Spring for the provision of request scoped beans.

You need to add this to your web.xml as described in the docs here:

<listener>
    <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
  </listener>

However, there is more to your question than just configuration. You are attempting to inject a request scoped bean into a singleton scoped bean. Spring resolves dependencies and instantiates singletons when the DI container starts. This means that ApplicationScopedBean will only be created once (at this point there will be no request in flight and so the autowiring will most likely fail).

If you were using a prototype scoped bean instead of request scoped you'd have to consider a way of suppling the singleton scoped bean with a fresh instance everytime it was used. The approaches for this are described in the Method Injection chapter of the Spring docs.