Question: Can We Have Two Beans With Same Name In Spring?

What is the life cycle of bean in spring?

The life cycle of a Spring bean is easy to understand.

When a bean is instantiated, it may be required to perform some initialization to get it into a usable state.

Similarly, when the bean is no longer required and is removed from the container, some cleanup may be required..

Is spring a singleton?

So, in summary, Java considers something a singleton if it cannot create more than one instance of that class within a given class loader, whereas Spring would consider something a singleton if it cannot create more than one instance of a class within a given container/context.

What is bean annotation in spring?

Annotating a class with the @Configuration indicates that the class can be used by the Spring IoC container as a source of bean definitions. The @Bean annotation tells Spring that a method annotated with @Bean will return an object that should be registered as a bean in the Spring application context.

Is spring a stateless?

stateless beans: beans that are singleton and are initialized only once. These beans are created while the ApplicationContext is being initialized. … The SAME bean instance will be returned/injected during the lifetime of this ApplicationContext. .

Why Spring bean is singleton by default?

singleton is default bean scope in spring container. It tells the container to create and manage only one instance of bean class, per container. This single instance is stored in a cache of such singleton beans, and all subsequent requests and references for that named bean return the cached instance.

Why Singleton is not thread safe?

In the above code, the getInstance() method is not thread-safe. Multiple threads can access it at the same time. For the first few threads when the instance variable is not initialized, multiple threads can enter the if loop and create multiple instances. It will break our singleton implementation.

How many instances are created for a spring managed bean?

For this particular graph of objects, Spring creates only one instance for each bean definition. Even though one of them is a prototype. If we had another bean depending on MessageBuilder, it would get another instance of the prototype bean. But in this case, Spring creates only one.

What is use of @autowired in spring?

The @Autowired annotation can be used to autowire bean on the setter method just like @Required annotation, constructor, a property or methods with arbitrary names and/or multiple arguments. …

How do I create a spring instance of a bean?

For example, to force Spring to produce a new bean instance each time one is needed, you should declare the bean’s scope attribute to be prototype. Similarly, if you want Spring to return the same bean instance each time one is needed, you should declare the bean’s scope attribute to be singleton.

Is @component a singleton?

Yes, that is correct, @Component is a Spring bean and a Singleton. About singletons – spring beans are all in singleton scope by default.

What is Proxymode in spring?

For those of you who are not aware of Method Injection, it allows you to inject methods instead of objects in your class. … Method Injection is useful in scenarios where you need to inject a smaller scope bean in a larger scope bean.

Can we have two beans with same ID in spring?

It valid as long as you are defining two bean definitions with same id of same bean on two different spring configuration files. … Spring would not let you define multiple bean definitions of same bean with same name in the same spring configuration file.

Can a bean have multiple names?

Bean Name Aliasing Spring allows a bean to have multiple names.

What is a bean in spring?

In Spring, the objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. Otherwise, a bean is simply one of many objects in your application.

How can we make Singleton bean thread safe in spring?

Spring will create a Singleton , but if its mutable then it might not be thread safe. IT’S programmer responsibility to take care the spring bean class such way it should be thread safe. In Spring, singleton beans will not have any state (stateless). Singleton bean scope ensures that single instance per BeanFactory.

What is the difference between @component and @bean?

Both approaches aim to register target type in Spring container. The difference is that @Bean is applicable to methods, whereas @Component is applicable to types. Therefore when you use @Bean annotation you control instance creation logic in method’s body (see example above). With @Component annotation you cannot.

Which is better EJB or Spring?

The main difference between EJB vs Spring is that EJB is a specification of Java EE whereas Spring is a framework or an implementation. … It makes the server-side development much easier for the Java developer. Spring framework is a Java platform that provides support for developing the Java application.

When Singleton beans are created in spring?

Singleton beans are created when the Spring container is created and are destroyed when the container is destroyed. Singleton beans are shared; only one instance of a singleton bean is created per Spring container. Singleton scope is the default scope for a Spring bean.

Does spring use EJB?

4 Answers. Spring was developed as an alternative to EJB right from its inception, so the answer is of course you can use Spring in place of EJBs. … App servers written to support the EJB standard can, in theory, be ported from one compliant Java EE app server to another.

Can we create multiple Singleton beans of same class in spring?

If you have more than one instance of class, it’s better to stick with XML configuration. It’s not possible.

Which scope creates a new bean instance each time when requested?

2 The prototype scope. The non-singleton, prototype scope of bean deployment results in the creation of a new bean instance every time a request for that specific bean is made. That is, the bean is injected into another bean or you request it through a getBean() method call on the container.

What is Singleton bean in spring?

This means that if you define one bean for a particular class in a single Spring container, then the Spring container will create one and only one instance of the class defined by that bean definition. The singleton scope is the default scope in Spring.

What is stateless bean in spring?

From spring perspective. stateless beans: beans that are singleton and are initialized only once. The only state they have is a shared state. These beans are created while the ApplicationContext is being initialized. The SAME bean instance will be returned/injected during the lifetime of this ApplicationContext .

How do you call a bean method in spring?

Spring @Bean Annotation is applied on a method to specify that it returns a bean to be managed by Spring context. Spring Bean annotation is usually declared in Configuration classes methods. In this case, bean methods may reference other @Bean methods in the same class by calling them directly.