Spring 3 - Dynamic Autowiring at runtime based on another object attribute

Question

I am working on a Spring 3.1 MVC application and for one of my scenarios, I had to write two implementations of a DAO. I would like to know how to autowire this in a service

Answer 1

There is an cleaner option to accomplish this strategy. We know Spring is smart enough to inject where it sees a bean that it has control over, so when it sees your VehicleDAO with an @Autowire or @Resource annotation, it will correctly inject that concrete implementation.

Keeping that in mind, this will work anywhere you ask Spring to perform dependency injection, using a Map<> or a List<> for instance.

// Injects the map will all VehicleDAO implementations where key = the
// concrete implementation (The default name is the class name, otherwise you 
// can specify the name explicitly).
@Autowired
private Map vehicleDAO;

// When you want to use a specific implementaion of VehicleDAO, just call the  
// 'get()' method on the map as in:
...
vehicleDAO.get("carDAO").yourMethod();
...