The Bean's scope properties in spring

When the scope of a bean is set to Singleton, only one shared bean instance exists in the spring IOC container, and all requests to the bean, as long as the ID matches the bean definition, will return only the same instance of the bean. In other words, when a bean definition is set to singleton scope, the Spring IOC container only creates a unique instance of the bean definition. This single instance is stored in the singleton cache (singleton cache), and all subsequent requests and references to the bean will return the cached object instance, noting that the singleton in the singleton scope and GOF design pattern is completely different, The singleton design pattern indicates that only one class exists in a ClassLoader, and here the singleton represents a container for a bean, which means that when a bean is identified as Singleton, Only one of the beans will exist in spring's IOC container.

Prototype-scoped beans, each request (injecting it into another bean, or invoking the container's Getbean () method programmatically) produces a new bean instance, which is equivalent to the operation of an For prototype-scoped beans, it is important to note that spring cannot be responsible for the entire life cycle of a prototype bean, which is given to the client after it is initialized, configured, decorated, or assembled with a prototype instance. The prototype instance is then ignored. Regardless of the scope, the container invokes the initialization lifecycle callback method for all objects, and for prototype, any configured destructor life-cycle callback methods will not be called. Clearing prototype-scoped objects and releasing expensive resources held by any prototype bean is the responsibility of the client code. (One possible way for the spring container to release the resource that is consumed by the singleton scope Bean is by using the bean's post processor, which holds a reference to the bean to be purged.) ）

As can be seen from the above, when you need the global unique indicator can be used singleton, and Singleton only create an object, the system consumes less resources. But with the singleton may be wired to secure the problem, this time need to use the prototype. Consider concurrency issues, and the recommendations are all used prototype.

The Bean's scope properties in spring