How to dynamically inject sub type dependencies in Spring mvc?

[abhinas raj]

public class ManageVehicles{

	@Autowired
	Vehicle vehicle;
}

public inteface Vehicle{

}

public class Ferrari implements Vehicle{

}

public class Lamborghini implements Vehicle{

}

public class Fiat implements Vehicle{

}

public class Bmw implements Vehicle{

}

from the UI i am selecting the vehicles, so i want that what vehicles i select from dropdown list that vehicle object
should be injected into 'vehicle'  variable declared inside ManageVehicles class. how to achieve this ?

[Tim Cooke]

Autowired isn't the right solution for this use case. In fact, your example given will fail to start as Spring will complain that it doesn't know which implementation of Vehicle it should inject.

You will need to write some code that will recognise the user input and create the correct implementation of Vehicle. The Factory Pattern might be a suitable approach to take here.

[abhinas raj]

Tim Cooke wrote:Autowired isn't the right solution for this use case. In fact, your example given will fail to start as Spring will complain that it doesn't know which implementation of Vehicle it should inject.

You will need to write some code that will recognise the user input and create the correct implementation of Vehicle. The Factory Pattern might be a suitable approach to take here.

yes right now it will fail. but if i have configured all the beans in spring config file spring container has to create the instances of the  beans. if i use factory pattern to create the objects based on the data passed from
ui then i think there is no use of using spring for this use case. i need to do it using features of spring  only. that's why i had to ask if there is any way in spring to achieve this use case.

[Tim Cooke]

abhinas raj wrote:i need to do it using features of spring  only

Why?

[abhinas raj]

Tim Cooke wrote:

abhinas raj wrote:i need to do it using features of spring  only

Why?

Actually i was asked this question in an interview. he was asking like there is some way to do that in spring because he told that you do not have to do it with factory design pattern.

[Tim Cooke]

If you have named your bean definitions then you could use

ApplicationContext.getBean(String name)

For example (pseudo-code)

String carName = fromUserInput();
Vehicle car = applicationContext.getBean(carName);

[abhinas raj]

Tim Cooke wrote:If you have named your bean definitions then you could use

ApplicationContext.getBean(String name)

For example (pseudo-code)

String carName = fromUserInput();
Vehicle car = applicationContext.getBean(carName);

will @Autowire with @Qualifier(vehicleName)  can help here ? we can get vehicleName from user and pass inside @Qualifier.

[Tim Cooke]

I'm pretty sure you can't pass variables into Java Annotations, so no that won't help.

[abhinas raj]

Tim Cooke wrote:I'm pretty sure you can't pass variables into Java Annotations, so no that won't help.

Thank you Tim for your reply