Spring s overriding bean

Question

Can we have duplicate names for the same bean id that is mentioned in the XML  If not  then how do we override the bean in Spring

User · Answer

Not sure if that s exactly what you need  but we are using profiles to define the environment we are running at and specific bean for each environment  so it s something like that    lt bean name  myBean  class  myClass  gt       lt constructor-arg name  name  value  originalValue    gt   lt  bean gt   lt beans profile  DEV  default  gt        lt  -- Specific DEV configurations  also default if no profile defined -- gt       lt bean name  myBean  class  myClass  gt           lt constructor-arg name  name  value  overrideValue    gt       lt  bean gt   lt  beans gt   lt beans profile  CI  UAT  gt        lt  -- Specific CI   UAT configurations -- gt   lt  beans gt   lt beans profile  PROD  gt        lt  -- Specific PROD configurations -- gt   lt  beans gt    So in this case  if I don t define a profile or if I define it as  DEV  myBean will get  overrideValue  for it s name argument  But if I set the profile to  CI    UAT  or  PROD  it will get  originalValue  as the value

User · Answer

Question was more about XML but as annotation are more popular nowadays and it works similarly I ll show by example  Let s create class Foo  public class Foo       private String name       public String getName             return name             public void setName String name            this name   name           and two Configuration files  you can t create one    Configuration public class Configuration1        Bean     public Foo foo             Foo foo   new Foo            foo setName  quot configuration1 quot            return foo           and  Configuration public class Configuration2        Bean     public Foo foo             Foo foo   new Foo            foo setName  quot configuration2 quot            return foo           and let s see what happens when calling foo getName     SpringBootApplication public class OverridingBeanDefinitionsApplication        public static void main String   args            SpringApplication run OverridingBeanDefinitionsApplication class  args            AnnotationConfigApplicationContext applicationContext                   new AnnotationConfigApplicationContext                          Configuration1 class  Configuration2 class            Foo foo   applicationContext getBean Foo class           System out println foo getName              in this example result is  configuration2  The Spring Container gets all configuration metadata sources and merges bean definitions in those sources  In this example there are two  Beans  Order in which they are fed into ApplicationContext decide  You can flip new AnnotationConfigApplicationContext Configuration2 class  Configuration1 class   and result will be configuration1

User · Answer

I will add that if your need is just to override a property used by your bean  the id approach works too like skaffman explained    In your first called XML configuration file        lt bean id  myBeanId  class  com blabla  gt          lt property name  myList  ref  myList   gt      lt  bean gt       lt util list id  myList  gt          lt value gt 3 lt  value gt          lt value gt 4 lt  value gt      lt  util list gt    In your second called XML configuration file        lt util list id  myList  gt          lt value gt 6 lt  value gt      lt  util list gt    Then your bean  myBeanId  will be instantiated with a  myList  property of one element which is 6

User · Answer

Whether can we declare the same bean id in other xml for other reference e x   Servlet-Initialize xml   lt bean id  inheritedTestBean    class  org springframework beans TestBean  gt     lt property name  name  value  parent   gt     lt property name  age  value  1   gt   lt  bean gt    Other xml  Document xml    lt bean id  inheritedTestBean   class  org springframework beans Document  gt     lt property name  name  value  document   gt     lt property name  age  value  1   gt   lt  bean gt

User · Answer

Any given Spring context can only have one bean for any given id or name  In the case of the XML id attribute  this is enforced by the schema validation  In the case of the name attribute  this is enforced by Spring s logic   However  if a context is constructed from two different XML descriptor files  and an id is used by both files  then one will  override  the other  The exact behaviour depends on the ordering of the files when they get loaded by the context   So while it s possible  it s not recommended  It s error-prone and fragile  and you ll get no help from Spring if you change the ID of one but not the other

User · Answer

Since Spring 3 0 you can use  Primary annotation  As per documentation      Indicates that a bean should be given preference when multiple   candidates are qualified to autowire a single-valued dependency  If   exactly one  primary  bean exists among the candidates  it will be the   autowired value  This annotation is semantically equivalent to the    element s primary attribute in Spring XML    You should use it on Bean definition like this    Bean  Primary public ExampleBean exampleBean  Autowired EntityManager em        return new ExampleBeanImpl em       or like this    Primary  Service public class ExampleService implements BaseServive

User · Answer

An example from official spring manual    lt bean id  inheritedTestBean  abstract  true      class  org springframework beans TestBean  gt     lt property name  name  value  parent   gt     lt property name  age  value  1   gt   lt  bean gt    lt bean id  inheritsWithDifferentClass        class  org springframework beans DerivedTestBean        parent  inheritedTestBean  init-method  initialize  gt     lt property name  name  value  override   gt     lt  -- the age property value of 1 will be inherited from  parent -- gt   lt  bean gt    Is that what you was looking for  Updated link

User · Answer

Another good approach not mentioned in other posts is to use PropertyOverrideConfigurer in case you just want to override properties of some beans   For example if you want to override the datasource for testing  i e  use an in-memory database  in another xml config  you just need to use  lt context property-override       gt  in new config and a  properties file containing key-values taking the format beanName property newvalue overriding the main props   application-mainConfig xml    lt bean id  dataSource       class  org apache commons dbcp BasicDataSource       p driverClassName  org postgresql Driver      p url  jdbc postgresql   localhost 5432 MyAppDB       p username  myusername       p password  mypassword      destroy-method  close    gt    application-testConfig xml    lt import resource  classpath path to file application-mainConfig xml   gt    lt  -- override bean props -- gt   lt context property-override location  classpath path to file beanOverride properties   gt    beanOverride properties   dataSource driverClassName org h2 Driver dataSource url jdbc h2 mem MyTestDB

[spring] Spring's overriding bean

Examples related to spring