How can I inject a bean into an ApplicationContext before it loads from a file?

Question

I have a FileSystemXmlApplicationContext and I would like the beans defined in the XML to take as a constructor argument a bean which is not declared in Spring

Answer 1

If the existing context needs the bean you wish to inject then things need to be done a little differently. The approaches in other answers don't work for the following reasons

• Context cannot be refreshed until the missing bean is registered
• refresh() causes the injected bean to be destroyed.

This can be worked around by using a "bean factory post processor", this allows code to be run after the context is loaded but before it it refreshed.

ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext();
applicationContext.setConfigLocation("/org/example/app-context.xml");
applicationContext.getBeanFactoryPostProcessors().add(new BeanFactoryPostProcessor() {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        beanFactory.registerSingleton("customBeanName", customBean);
    }
});
applicationContext.refresh();