Spring Tip: Check for existence of Bean during startup

Sometimes we are working on an application where we have no control over specific Spring bean implementations. Nevertheless we want to check for the existence (or duplication) of these bean implementations during start-up of the application server. Since Spring version 3.0 it is possible to use Spring’s ApplicationListener. This interface is based on the EventListener and uses the standard Observer design pattern.

In 3 steps we can easily check for the existence of a specific Spring bean.
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