Spring. How bean injection works when there are more than one bean with the same qualifier?












1















Lets assume you have the following Classes extending the Processor interface:



Interface Processor {}

class ProcesorImpl1 implements Processor {}

class ProcesorImpl2 implements Processor {}


Now, Lets assume that you define the following bean in a configuration class in package1:



class ConfigurationClass1 {

@Bean
@Qualifier("processor")
public Processor processor() {
return new ProcesorImpl1();
}

}


Next, you define the following bean in a configuration class in package2:



class ConfigurationClass2 {

@Bean
@Qualifier("processor")
public Processor anotherProcessor() {
return new ProcesorImpl2();
}

}


The question is how does Spring resolves the following Injection:



@Inject @Qualifier("processor") proc;


What if one of the Beans are annotated with @Primary?










share|improve this question



























    1















    Lets assume you have the following Classes extending the Processor interface:



    Interface Processor {}

    class ProcesorImpl1 implements Processor {}

    class ProcesorImpl2 implements Processor {}


    Now, Lets assume that you define the following bean in a configuration class in package1:



    class ConfigurationClass1 {

    @Bean
    @Qualifier("processor")
    public Processor processor() {
    return new ProcesorImpl1();
    }

    }


    Next, you define the following bean in a configuration class in package2:



    class ConfigurationClass2 {

    @Bean
    @Qualifier("processor")
    public Processor anotherProcessor() {
    return new ProcesorImpl2();
    }

    }


    The question is how does Spring resolves the following Injection:



    @Inject @Qualifier("processor") proc;


    What if one of the Beans are annotated with @Primary?










    share|improve this question

























      1












      1








      1


      1






      Lets assume you have the following Classes extending the Processor interface:



      Interface Processor {}

      class ProcesorImpl1 implements Processor {}

      class ProcesorImpl2 implements Processor {}


      Now, Lets assume that you define the following bean in a configuration class in package1:



      class ConfigurationClass1 {

      @Bean
      @Qualifier("processor")
      public Processor processor() {
      return new ProcesorImpl1();
      }

      }


      Next, you define the following bean in a configuration class in package2:



      class ConfigurationClass2 {

      @Bean
      @Qualifier("processor")
      public Processor anotherProcessor() {
      return new ProcesorImpl2();
      }

      }


      The question is how does Spring resolves the following Injection:



      @Inject @Qualifier("processor") proc;


      What if one of the Beans are annotated with @Primary?










      share|improve this question














      Lets assume you have the following Classes extending the Processor interface:



      Interface Processor {}

      class ProcesorImpl1 implements Processor {}

      class ProcesorImpl2 implements Processor {}


      Now, Lets assume that you define the following bean in a configuration class in package1:



      class ConfigurationClass1 {

      @Bean
      @Qualifier("processor")
      public Processor processor() {
      return new ProcesorImpl1();
      }

      }


      Next, you define the following bean in a configuration class in package2:



      class ConfigurationClass2 {

      @Bean
      @Qualifier("processor")
      public Processor anotherProcessor() {
      return new ProcesorImpl2();
      }

      }


      The question is how does Spring resolves the following Injection:



      @Inject @Qualifier("processor") proc;


      What if one of the Beans are annotated with @Primary?







      spring dependency-injection






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Jan 18 at 4:51









      luismattorluismattor

      162




      162
























          1 Answer
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          Qualifier doesn't work with @Bean annotation, but @Primary does and it will define what concrete bean will be injected if you inject a bean by type and there is multiple bean of this type managed by Spring. If you want to inject another non-primary bean, you can mark it with @Qualifier("beanName") annotation to inject it by name.
          If you define 2 bean with the same names and the same types like this



          class ConfigurationClass1 {

          @Bean("processor")
          public Processor processor() {
          return new ProcesorImpl1();
          }

          }

          class ConfigurationClass2 {

          @Bean("processor")
          public Processor anotherProcessor() {
          return new ProcesorImpl2();
          }

          }


          Spring will override the first loaded bean within the second and only single will stay in container, because of allowBeanDefinitionOverriding property is set to true by default.






          share|improve this answer








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            1 Answer
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            1 Answer
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            active

            oldest

            votes









            1














            Qualifier doesn't work with @Bean annotation, but @Primary does and it will define what concrete bean will be injected if you inject a bean by type and there is multiple bean of this type managed by Spring. If you want to inject another non-primary bean, you can mark it with @Qualifier("beanName") annotation to inject it by name.
            If you define 2 bean with the same names and the same types like this



            class ConfigurationClass1 {

            @Bean("processor")
            public Processor processor() {
            return new ProcesorImpl1();
            }

            }

            class ConfigurationClass2 {

            @Bean("processor")
            public Processor anotherProcessor() {
            return new ProcesorImpl2();
            }

            }


            Spring will override the first loaded bean within the second and only single will stay in container, because of allowBeanDefinitionOverriding property is set to true by default.






            share|improve this answer








            New contributor




            Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.

























              1














              Qualifier doesn't work with @Bean annotation, but @Primary does and it will define what concrete bean will be injected if you inject a bean by type and there is multiple bean of this type managed by Spring. If you want to inject another non-primary bean, you can mark it with @Qualifier("beanName") annotation to inject it by name.
              If you define 2 bean with the same names and the same types like this



              class ConfigurationClass1 {

              @Bean("processor")
              public Processor processor() {
              return new ProcesorImpl1();
              }

              }

              class ConfigurationClass2 {

              @Bean("processor")
              public Processor anotherProcessor() {
              return new ProcesorImpl2();
              }

              }


              Spring will override the first loaded bean within the second and only single will stay in container, because of allowBeanDefinitionOverriding property is set to true by default.






              share|improve this answer








              New contributor




              Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
              Check out our Code of Conduct.























                1












                1








                1







                Qualifier doesn't work with @Bean annotation, but @Primary does and it will define what concrete bean will be injected if you inject a bean by type and there is multiple bean of this type managed by Spring. If you want to inject another non-primary bean, you can mark it with @Qualifier("beanName") annotation to inject it by name.
                If you define 2 bean with the same names and the same types like this



                class ConfigurationClass1 {

                @Bean("processor")
                public Processor processor() {
                return new ProcesorImpl1();
                }

                }

                class ConfigurationClass2 {

                @Bean("processor")
                public Processor anotherProcessor() {
                return new ProcesorImpl2();
                }

                }


                Spring will override the first loaded bean within the second and only single will stay in container, because of allowBeanDefinitionOverriding property is set to true by default.






                share|improve this answer








                New contributor




                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.










                Qualifier doesn't work with @Bean annotation, but @Primary does and it will define what concrete bean will be injected if you inject a bean by type and there is multiple bean of this type managed by Spring. If you want to inject another non-primary bean, you can mark it with @Qualifier("beanName") annotation to inject it by name.
                If you define 2 bean with the same names and the same types like this



                class ConfigurationClass1 {

                @Bean("processor")
                public Processor processor() {
                return new ProcesorImpl1();
                }

                }

                class ConfigurationClass2 {

                @Bean("processor")
                public Processor anotherProcessor() {
                return new ProcesorImpl2();
                }

                }


                Spring will override the first loaded bean within the second and only single will stay in container, because of allowBeanDefinitionOverriding property is set to true by default.







                share|improve this answer








                New contributor




                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                share|improve this answer



                share|improve this answer






                New contributor




                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                answered Jan 18 at 12:26









                Artur VakhrameevArtur Vakhrameev

                988




                988




                New contributor




                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                New contributor





                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                Artur Vakhrameev is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






























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