[cdi-dev] Proposal: Improve producer method signature capability by accepting qualifier annotations

Mark Paluch mpaluch at paluch.biz
Fri Aug 1 14:16:17 EDT 2014

CDI supports producer methods which accept the InjectionPoint as argument which allows to access all metadata to the injection point. The InjectionPoint approach adds a certain complexity which is not needed when only qualifier metadata has to be processed. I propose to allow annotation types within the producer method signatures. Code example for a use case: 

@HttpParam("username") @Inject String username

import javax.enterprise.inject.Produces;
import javax.enterprise.inject.spi.InjectionPoint;

class HttpParams

   String getParamValue(HttpParam httpParam) {

      ServletRequest request = (ServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
      return request.getParameter(httpParam.value());
      // current support looks like:
      // String getParamValue(InjectionPoint ip) {
      // return request.getParameter(ip.getAnnotated().getAnnotation(HttpParam.class).value());


Producer methods accepting qualifier annotations ensure to have always an annotation instance, this helps to prevent null pointer access since InjectionPoint.getAnnotated().getAnnotation(java.lang.Class<T>) may return null.

Best regards, Mark


Heckenpfad 14 // 69469 Weinheim
T. 0 62 01/65 04 24-0 // F. 0 62 01/65 04 24-9
mpaluch at paluch.biz

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