Turn a Java annotation into a CDI qualifier

A. Programmer

Apr. 25, 11 · Interview

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A CDI qualifier is an annotation that itself is annotated with the @javax.inject.Qualifier meta-annotation. Per example, if you add the @Qualifier to the MyAnnotation (http://e-blog-java.blogspot.com/2011/04/what-is-java-annotation.html) you obtain a CDI qualifier:

@Qualifier
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation 
 {
  // Property Definitions here.
   }

CDI provide a set of built-in qualifiers:

Qualifier	Description
@javax.enterprise.inject.Named	This qualifier is used to un-typed access from non-Java code. Commonly this qualifier serves the JSF pages that access beans through EL.
@javax.enterprise.inject.New	This qualifier forces the creation of a new instance, instead of using the contextual instance. It allows us to obtain a dependent object of a specified class.
@javax.enterprise.inject.Any	This qualifier “belongs” to all beans and injection points (not applicable when @New is present). This is useful if you want to iterate over all beans with a certain bean type.
@javax.enterprise.inject.Default	As the qualifier name suggests, whenever a bean or injection point does not explicitly declare a qualifier, the container assumes the qualifier @Default.

CDI Annotation Java (programming language)

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