Accessing application context

[sherihan]

Hi,
I would like to know how I could access the application context in a class not instantiated by spring.

I was able to the access the application context before in classes instantiated by spring by implenting ApplicationContextAware.

But in the current case when I tried to implement ApplicationContextAware the applicationContext is always null.

Could anyone help me in that?

Thanks in advance.

Sherihan.

[Arthur Loder]

Hi Sherihan,

Although it is a best practice to avoid writing container-aware code, there are certain circumstances in which this is necessary. Like you said, it can be a problem when Spring cannot be used to instantiate the class. An example of this is with EJBs, because the EJB container is responsible for creating them. Spring provides EJB-specific solutions for this issue.

I think your best bet might be to use either the SingletonBeanFactoryLocator or the ContextSingletonBeanFactoryLocator.

Here is a short summary from the Spring documentation: Glue code and the evil singleton.

Assuming you have a simple application with only one ApplicationContext (named "myApplicationContext.xml"), here is what I would suggest:

1) Create a new file, beanRefFactory.xml (which is the default name):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
 
<beans>
   <bean id="mainApplicationContext" lazy-init="true" class="org.springframework.context.support.ClassPathXmlApplicationContext">
      <constructor-arg>
         <value>myApplicationContext.xml</value>
      </constructor-arg>
   </bean>
</beans>

2) In the classes that require access to the ApplicationContext, add the following code:

public class SomeClassWhichNeedsAppContextAccess {

   public static final String BEAN_FACTORY_KEY = "mainApplicationContext";

   public Object getBean(String beanName) {
      BeanFactoryLocator locator = SingletonBeanFactoryLocator.getInstance();
      BeanFactoryReference bfr = locator.useBeanFactory(BEAN_FACTORY_KEY);
      Object object = bfr.getFactory().getBean(beanName);
      bfr.release();
      return object;
   }

}

Now this of course assumes that the classes in question can be modified. Can you provide more details as to your exact problem?

Hope this helps!

-Arthur Loder