@Scope annotation, and in XML it is the scope attribute of the <bean> tag.The 'scope' attribute is an identifier string that associates a bean with an instance of the class
org.springframework.beans.factory.config.Scope.Scope is an implementation of the "strategy" pattern for bean factories, a recipe to create business objects.In the simplest Spring application, there are always two scopes:
• singleton – the object is created once and reused in subsequent injections. It is useful for most cases: various services, stateless objects, immutable objects. It is important to note that this is not a singleton class: declaring two beans of the same class results in two instances. This is the default scope.
• prototype – each injection results in the creation of a new object by the bean factory. This is necessary for mutable beans with state.
Spring Web adds four additional scopes, which makes a bean behave like a singleton within the confines of handling a single network request (request), a client session (session), a servlet context (application) and a websocket session (websocket).
Developers can add their own scopes. An example implementation can be found in the Spring source itself:
SimpleThreadScope, which makes the bean thread-local. To use it, as well as custom scopes, you must first register it in the BeanFactory.