@Bean (autowire = Autowire.BY_NAME)

Question

What is the purpose of setting the autowire property of @Bean to *Autowire.BY_NAME*

Looking at the JavDocs, I dont really know when I would use this, or why it would be set to *Autowire.BY_NAME*

/**
 * Are dependencies to be injected via autowiring?
 */
Autowire autowire() default Autowire.NO;

I have an existing prototype bean that is created with

@Bean (autowire = Autowire.BY_NAME)

But I dont understand why. The comments only state:

Note: We have to explicitly set Autowire.BY_NAME in the bean definitions to be able to use @Autowired in other spring config classes

Does this mean we have to set a bean to @Bean (autowire = Autowire.BY_NAME) in order to be able to use the Bean with @Autowired and it will be autowired by name from the @Bean?

Answer 1

@Bean(autowire=Autowire.BY_NAME) is the equivalent of this xml configuration:

<bean class="Person" id="person" autowire="byName"></bean>

which indicates whether the bean created using the above Person class, needs to have its fields autowired in "by name" - if the test bean above has a field say address , Spring will look for a bean with name address to inject as a dependency(not by type Address ).

This is typically used if it is possible that there are more than 1 instances of a particular type, then you would select the specific instance using a name - again consider the example above if there were to be two address beans with names addressHome , addressWork and if Person class had a field with name addressHome and its set to Autowire.BY_NAME , the bean with name addressHome will be set to the field. Had it been Autowire.BY_TYPE it would have failed as there are two instances of address of the same type Address

Answer 2

As @Bean (autowire = Autowire.BY_NAME) is deprecated.

No syntactical alternative, Autowire by Name is understood. You just have to provide same name as @Bean method name or @Component name.