How to Autowire Bean of generic type in Spring?

Question

I have a bean Item which is required to be autowired in a @Configuration class.

@Configuration
public class AppConfig {

          


        

Answer 1

Simple solution is to upgrade to Spring 4.0 as it will automatically consider generics as a form of @Qualifier, as below:

@Autowired
private Item strItem; // Injects the stringItem bean

@Autowired
private Item intItem; // Injects the integerItem bean

Infact, you can even autowire nested generics when injecting into a list, as below:

// Inject all Item beans as long as they have an  generic
// Item beans will not appear in this list
@Autowired
private List> intItems;

How this Works?

The new ResolvableType class provides the logic of actually working with generic types. You can use it yourself to easily navigate and resolve type information. Most methods on ResolvableType will themselves return a ResolvableType, for example:

// Assuming 'field' refers to 'intItems' above
ResolvableType t1 = ResolvableType.forField(field); // List> 
ResolvableType t2 = t1.getGeneric(); // Item
ResolvableType t3 = t2.getGeneric(); // Integer
Class c = t3.resolve(); // Integer.class

// or more succinctly
Class c = ResolvableType.forField(field).resolveGeneric(0, 0);

Check out the Examples & Tutorials at below links.

• Spring Framework 4.0 and Java Generics
• Spring and Autowiring of Generic Types

Hope this helps you.