CODEWITHSUNDEEP
springspring-boot
chris01
chris01

Reputation: 12321

Spring-Boot: share an object between components

I have a custom object which I like to share between different Spring-Boot components (e.g. WebHandler, Authenticator, Filter).

Maybe the easiest way is a static object in the main-class but thats not very elegant.

Whats the most common way to do it?

Upvotes: 0

Views: 1398

Answers (2)

Mark Bramnik
Mark Bramnik

Reputation: 42441

The whole point of spring as a container is to manage your objects.

Now statics do not have a well defined lifecycle ( when exactly this object gets created, who disposes it when the application gets closed, etc)

Speing answers all these questions by using thecdependency injection techniques. If you're already using spring then you should define this 'shared object' as a spring bean (by default it will have scope singleton just like static object that you've proposed but managed by spring container which is better - it will manage the lifecycle of the object by itself)

Then given the classes that must be dependent of the object are beans by themselves you can inject that bean:

class MySharedObject {}

class MyWebHandler implementsWebHandler {
  private final MySharedObject mySharedObject;

public MyWebHandler(MySharedObject mySharedObject) {
  this.mySharedObject = mySharedObject;

In addition to the lifecycle management this way allows easy unit testing of classes that use the shared object (like 'MyWebHandler' in this case) - now uou can create a stub/mock of the shared object and pass it into the handler - something that cannot really be easily done when using statics

So in summary if you can use spring and define it as a bean - by all means do so, the usage of statics is discouraged if you already have a dependency injection container

Upvotes: 1

Mykhailo Moskura
Mykhailo Moskura

Reputation: 2211

If you have shared object first of all it should not contain any state as differents components can change it and also it should be thread safe. It is fine to reuse it across all components via @Autowired annotation but you need to be sure that it is threadsafe. Spring bean scope singleton is not thread safe out of box it dependes how you write the code.

You can use as static method but it dependes on logic which you have and if those component has an dependency on another objects and if they need to in spring IOC.

Upvotes: 1

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