Saturday, 27 July 2019

Spring Boot – How to display all beans available in ApplicationContext?

A Guide to Displaying All Beans in Spring Boot's ApplicationContext

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Understanding the ApplicationContext

In the world of Spring Boot, the ApplicationContext is the engine that drives everything. It is the central interface to provide configuration information to the application. One of its primary jobs is to manage "Beans"—the objects that form the backbone of your application. But have you ever wondered exactly which beans are currently "alive" and managed by Spring at runtime?

Why List All Beans?

Listing all loaded beans is a fantastic debugging technique. Whether you're trying to figure out if your @Component was scanned correctly, or you want to see the various auto-configured beans Spring Boot has added for you, inspecting the context gives you a transparent look into your application's internals.

The Simple Implementation

The easiest way to see your beans is to fetch the ApplicationContext and call getBeanDefinitionNames(). This returns an array of all bean names, which you can then sort and print. Here is a quick look at how you might do this in a startup class:

String[] beanNames = ctx.getBeanDefinitionNames(); Arrays.sort(beanNames); for (String beanName : beanNames) {     System.out.println(beanName); }

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