春季原型豆迷

Question

Consider the following classes:

@Component
@Scope(scopeName = "prototype", proxyMode = ScopedProxyMode.TARGET_CLASS)
class PrototypeBean
{
    public void method1() { ... };
    public void method2() { ... };
}

@Component
public class SingletonBean
{
   @Autowired
   private PrototypeBean prototypeBean;

   public void SingletonBean doSomething()
   {
      prototypeBean.method1();
      prototypeBean.method2();

   }
}

Now, I would expect that everytime doSomething() method is called, a new PrototypeBean instance is created and injected to SingletonBean. But what really happens is a new PrototypeBean instance is created and injected into SingletonBean when I call method1() and method2().

I don't really get why, this should've worked as far is I'm concerned. Please correct my if I'm wrong.

Answer 1

是的，这是可以预料的，因为仅按需初始化bean，对于原型范围，每次需要时都会初始化bean。

Answer 2

Yes, That is expected !!

Because you declared the bean's scope attribute as prototype @Scope(scopeName = "prototype") that force the Spring IoC container creates a new bean instance of the object every time a request for that specific bean is made.

Note:As a rule, use the prototype scope for all state-full beans and the singleton scope for stateless beans.