What are Spring Bean Scopes (singleton, prototype, request, session)? स्प्रिंग बीन स्कोप्स (singleton, prototype, request, session) क्या हैं?

Bean scope defines how many instances of a bean the container creates and how long they live. singleton (the default) creates exactly one shared instance per Spring container, reused for every injection point. prototype creates a new instance every time the bean is requested from the container.

Web-aware scopes are also available when using a web application context: request creates one instance per HTTP request, session creates one instance per HTTP session, and application ties an instance to the ServletContext lifecycle. Choosing the wrong scope is a common source of bugs — e.g. injecting a prototype bean into a singleton without a scoped proxy means the prototype is only created once, defeating its purpose.

@Component
@Scope("prototype")
public class ShoppingCart { ... }

@Component
@Scope(value = WebApplicationContext.SCOPE_REQUEST, proxyMode = ScopedProxyMode.TARGET_CLASS)
public class RequestContext { ... }