Spring -- inject 2 beans of same type
JavaSpringJava Problem Overview
I like constructor-based injection as it allows me to make injected fields final
. I also like annotation driven injection as it simplifies my context.xml
. I can mark my constructor with @Autowired
and everything works fine, as long as I don't have two parameters of the same type. For example, I have a class:
@Component
public class SomeClass {
@Autowired(required=true)
public SomeClass(OtherClass bean1, OtherClass bean2) {
…
}
}
and an application context with:
<bean id="bean1" class="OtherClass" />
<bean id="bean2" class="OtherClass" />
There should be a way to specify the bean ID on the constructor of the class SomeClass
, but I can't find it in the documentation. Is it possible, or am I dreaming of a solution that does not exist yet?
Java Solutions
Solution 1 - Java
@Autowired
is by-type (in this case); use @Qualifier
to autowire by-name, following the example http://static.springsource.org/spring/docs/2.5.x/reference/beans.html">from spring docs:
public SomeClass(
@Qualifier("bean1") OtherClass bean1,
@Qualifier("bean2") OtherClass bean2) {
...
}
> Note: In contrast to @Autowired which is applicable to fields, constructors and multi-argument methods (allowing for narrowing through qualifier annotations at the parameter level), @Resource is only supported for fields and bean property setter methods with a single argument. As a consequence, stick with qualifiers if your injection target is a constructor or a multi-argument method.
(below that text is the full example)