How to instantiate more CDI beans for one class?

问题

Note: The similar question has been already asked three years ago, in time of EE 6, see how to instantiate more then one CDI/Weld bean for one class? Has something changed in EE 7?

In Spring there is possible to instantiate any class by defining the corresponding bean in xml conf. It is also possible to instantiate more beans for one class with different parameters.....

Is it possible to do it in CDI, I mean to create an instance without creating another class?

Spring Example:

<bean id="foo" class="MyBean">
    <property name="someProperty" value="42"/>
</bean>
<bean id="hoo" class="MyBean">
    <property name="someProperty" value="666"/>      
</bean>

回答1:

I would create qualifiers FooQualifier,HooQualifier and Producer for MyBean, something like this:

@ApplicationScoped
public class MyBeanProducer {

    @Produces
    @FooQualifier
    public MyBean fooProducer() {
        return new MyBean(42);
    }

    @Produces
    @HooQualifier
    public MyBean hooProducer() {
        return new MyBean(666);
    }
}

Then if you somewhere do:

    @Inject
    @FooQualifier
    private MyBean foo;

You will have MyBean instance with foo.getSomeProperty() equal to 42 and if you do:

@Inject
@HooQualifier
private MyBean hoo;

you will have MyBean instance with foo.getSomeProperty() equal to 666.

Another possibility is to have one configurable qualifier:

@Target( { TYPE, METHOD, PARAMETER, FIELD })
@Retention(RUNTIME)
@Documented
@Qualifier
public @interface ConfigurableQualifier {

    @Nonbinding
    int value() default 0;
}

and then producer method:

@Produces
@ConfigurableQualifier
public MyBean configurableProducer(InjectionPoint ip){
    int somePropertyValue = ip.getAnnotated().getAnnotation(ConfigurableQualifier.class).value();
    return new MyBean(somePropertyValue);
}

then simply calling:

@Inject
@ConfigurableQualifier(value = 11)
private MyBean configurableBean;

will result in MyBean instance with someProperty equal to 11.

来源：https://stackoverflow.com/questions/25153624/how-to-instantiate-more-cdi-beans-for-one-class

标签

java

cdi

java-ee-7