CDI 注入 bean 是否需要 getter 和 setter？

Question

When a bean is injected using CDI:

@Inject Person person;

Is a setter and getter needed/recommended?

import javax.inject.Inject;
import javax.inject.Named;

@Named
@SessionScoped
public class myJSFBean{

  @Inject Person person;

  public void setPerson (Person person){
    this.person = person;
  }
  public Person getPerson (){
    return person;
  }

I have found this documentation, but I don't understand what it means: http://docs.oracle.com/javaee/6/tutorial/doc/gjbbp.html

Answer 1

According to Weld Documentation :

Notice that it isn't necessary to create a getter or setter method to inject one bean into another. CDI can access an injected field directly (even if it's private!), which sometimes helps eliminate some wasteful code. The name of the field is arbitrary. It's the field's type that determines what is injected.

Answer 2

CDI ( Container Dependency Injection ) within Java EE 6 application can target different injection points: fields, constructors and setters .

So the short answer is no , you do not need a setter method if you won't be using it as the injection point.

The getter can be ignored as well unless you need one to access the field state (which by experience does not make much sence in a CDI environment, the same field that has been injected by the container still can be accessed through it in other components).

Answer 3

I would even consider a getter harmful.

Due to the encapsulation principle, getters and setters are public by default in most IDEs and in your example above, too. This means you pollute your autocomplete with CDI injects. These shouldn't be visible outside of your class.

If you access an @ApplicationScoped been via a getter in a @RequestScoped bean, the request scoped bean will always be instantiated needlessly, which costs performance. CDI beans should always be injected where they are needed and not being accessed across beans. You will prevent CDI from handling your scopes correctly.

So all there is really left is a private getter, which is superfluous anyway, because you will never have to modify a cdi bean before you return it.