ApplicationScoped

ApplicationScoped is a scope annotation used in CDI-based applications to control the lifecycle of beans. It indicates that a bean instance is shared across the entire application and survives for the duration of the application’s life. In Java EE and Jakarta EE contexts, the annotation is typically found as javax.enterprise.context.ApplicationScoped (older CDI) or jakarta.enterprise.context.ApplicationScoped (Jakarta namespace).

In practice, a bean annotated with ApplicationScoped is created once (either at deployment or on first use) and the same instance is injected wherever needed within the same application. The container may use a proxy to enable injection into other scopes (such as request or session scopes) while maintaining a single underlying instance. The lifetime ends when the application is stopped or undeployed, depending on the container’s shutdown sequence.

Common use cases for ApplicationScoped beans include configuration data, expensive or shared resources, service facades, and caches that should be available globally throughout the application. Because the same instance serves all threads, such beans should be thread-safe and preferably stateless or designed to handle concurrent access. If state is stored, synchronization or concurrency controls may be necessary.

Notes and considerations: ApplicationScoped is distinct from EJB’s @Singleton and from per-request or per-session scopes. In clustered or multi-node deployments, each application instance maintains its own ApplicationScoped instance. Lifecycle callbacks such as @PostConstruct and @PreDestroy can be used to initialize and clean up resources when the application context starts up or shuts down.