Correct way of retrieving another bean instance from context [duplicate]

This question already has answers here: Get JSF managed bean by name in any Servlet related class (6 answers) Closed 2 years ago.

We are using the following code to get the managed bean instance from the context.

FacesUtils.开发者_开发知识库getManagedBean("beanName");

Is it the correct way of doing it?. If multiple users access the same bean what will happen? How the bean instances are managed?

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Since FacesUtils is not part of standard JSF implementation, it's unclear what it is actually doing under the covers.

Regardless, when you're already inside a managed bean, then the preferred way is to inject the other bean as managed property. I'll assume that you're already on JSF 2.0, so here's a JSF 2.0 targeted example.

@ManagedBean
@SessionScoped
public void OtherBean {}

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@ManagedBean
@RequestScoped
public void YourBean {

    @ManagedProperty("#{otherBean}")
    private void OtherBean;

    @PostConstruct
    public void init() {
        otherBean.doSomething(); // OtherBean is now available in any method.
    }

    public void setOtherBean(OtherBean otherBean) {
        this.otherBean = otherBean;
    }

    // Getter is not necessary.
}

But when you're still on JSF 1.x, then you need to do it by <managed-property> entry in faces-config.xml as explained in this question: Passing data between managed beans.

If you happen to use CDI @Named instead of JSF @ManagedBean, use @Inject instead of @ManagedProperty. For this, a setter method is not required.

See also:

• Communication in JSF2
• Get JSF managed bean by name in any Servlet related class
• Backing beans (@ManagedBean) or CDI Beans (@Named)?

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As to your concern

If multiple users access the same bean what will happen? How the bean instances are managed?

They are managed by JSF. If a bean is found, then JSF will just return exactly this bean. If no bean is found, then JSF will just auto-create one and put in the associated scope. JSF won't unnecessarily create multiple beans.