spring autowiring with unique beans Spring expected single matching bean but found 2

Question

I am trying to autowire some beans  for dependency injection  using Spring for a webapp   One controller bean contains another bean which in turn holds a hashmap of another set of beans   For now the map only has one entry   When i run in tomcat and call the service I get an error saying that the second bean  held in the controller  is not unique   No unique bean of type  com hp it km search web suggestion SuggestionService  is defined  expected single matching bean but found 2   suggestionService  SuggestionService    I cannot see where I am defining the bean twice however  am new to Spring and autowiring so I may be missing something fundamental   Source code for xml and 2 class listed below      lt  xml version  1 0  encoding  UTF-8   gt   lt beans xmlns  http   www springframework org schema beans      xmlns context  http   www springframework org schema context      xmlns mvc  http   www springframework org schema mvc  xmlns xsi  http   www w3 org 2001 XMLSchema-instance  xsi schemaLocation       http   www springframework org schema beans          http   www springframework org schema beans spring-beans-3 0 xsd     http   www springframework org schema context      http   www springframework org schema context spring-context-3 0 xsd     http   www springframework org schema mvc     http   www springframework org schema mvc spring-mvc-3 0 xsd  gt    lt context component-scan base-package  com hp it km search web suggestion    gt   lt mvc annotation-driven   gt   lt context annotation-config   gt    lt bean id  SuggestionController  class  com hp it km search web suggestion SuggestionController  gt       lt property name  service  gt           lt ref bean  SuggestionService    gt       lt  property gt   lt  bean gt    lt bean id  SuggestionService  class  com hp it km search web suggestion SuggestionService  gt       lt property name  indexSearchers  gt             lt map gt               lt entry key  KMSearcher  gt   lt ref bean  KMSearcherBean  gt  lt  ref gt  lt  entry gt           lt  map gt       lt  property gt   lt  bean gt    lt bean id  KMSearcherBean  class  com hp it km search web suggestion SuggestionIndexSearcher  gt         lt constructor-arg index  0  value  KMSearcher    gt         lt constructor-arg index  1  value  C   dev  workspace  search-restful-webapp  src  main  resources  indexes  keyword    gt   lt  bean gt      The class asscoaites with the autowired controller and service bean are here      Controller public class SuggestionController   private SuggestionService service    Autowired public void setService SuggestionService service        this service   service     public SuggestionService getService         return service      and      Component public class SuggestionService    private Map lt String  IndexSearcher gt  indexSearchers   new HashMap lt String       IndexSearcher gt       Autowired public void setIndexSearchers Map lt String  IndexSearcher gt  indexSearchers        this indexSearchers   indexSearchers         public SuggestionService         super        Please Help

User · Accepted Answer

The issue is because you have a bean of type SuggestionService created through @Component annotation and also through the XML config . As explained by JB Nizet, this will lead to the creation of a bean with name 'suggestionService' created via @Component and another with name 'SuggestionService' created through XML .

When you refer SuggestionService by @Autowired, in your controller, Spring autowires "by type" by default and find two beans of type 'SuggestionService'

You could do the following

Remove @Component from your Service and depend on mapping via XML - Easiest
Remove SuggestionService from XML and autowire the dependencies - use util:map to inject the indexSearchers map.

Use @Resource instead of @Autowired to pick the bean by its name .

 @Resource(name="suggestionService")
 private SuggestionService service;

or

    @Resource(name="SuggestionService")
    private SuggestionService service;

both should work.The third is a dirty fix and it's best to resolve the bean conflict through other ways.

User · Answer

If you have 2 beans of the same class autowired to one class you shoud use  Qualifier  Spring Autowiring  Qualifier example    But it seems like your problem comes from incorrect Java Syntax   Your object should start with lower case letter   SuggestionService suggestion    Your setter should start with lower case as well and object name should be with Upper case   public void setSuggestion final Suggestion suggestion        this suggestion   suggestion

User · Answer

If I m not mistaken  the default bean name of a bean declared with  Component is the name of its class its first letter in lower-case  This means that    Component public class SuggestionService     declares a bean of type SuggestionService  and of name suggestionService  It s equivalent to   Component  suggestionService   public class SuggestionService     or to    lt bean id  suggestionService       gt    You re redefining another bean of the same type  but with a different name  in the XML    lt bean id  SuggestionService  class  com hp it km search web suggestion SuggestionService  gt           lt  bean gt    So  either specify the name of the bean in the annotation to be SuggestionService  or use the ID suggestionService in the XML  don t forget to also modify the  lt ref gt  element  or to remove it  since it isn t needed   In this case  the XML definition will override the annotation definition

User · Answer

For me it was case of having two beans implementing the same interface  One was a fake ban for the sake of unit test which was conflicting with original bean  If we use      component  suggestionServicefake       it still references with suggestionService   So I removed  component and only used      Qualifier  suggestionServicefake     which solved the problem

[spring] spring autowiring with unique beans: Spring expected single matching bean but found 2

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