Interface indicating a component that contains and exposes an Environment reference.

All Spring application contexts are EnvironmentCapable, and the interface is used primarily for performing instanceof checks in framework methods that accept BeanFactory instances that may or may not actually be ApplicationContext instances in order to interact with the environment if indeed it is available.

As mentioned, ApplicationContext extends EnvironmentCapable, and thus exposes a getEnvironment() method; however, ConfigurableApplicationContext redefines getEnvironment() and narrows the signature to return a ConfigurableEnvironment. The effect is that an Environment object is 'read-only' until it is being accessed from a ConfigurableApplicationContext, at which point it too may be configured.