春天打电话给工厂自动接线

Question

Is there any way to have spring call a factory with a runtime parameter of the type of the parent class of a variable it is trying to autowire?

For example, let's say I have something like this:

interface IConfig {
}

interface IConfigProvider {

    IConfig getConfig(Class<?> type)
}

class MyClass {

    @Autowired
    private IConfig _config;
}

Is there anyway to have spring, when autowiring MyClass._config to essentially call IConfigProvider.getConfig(MyClass.class) (well the concrete version that is in the context) at runtime to wire the variable?

I know I could autowire the factory and call it myself, I could even "hide" it in a base class but I am trying to avoid this.

NOTE: I am very new to Spring so if I am asking something really stupid/not using the right terminology, I apologise.

Answer 1

You would need to create a FactoryBean for that. Something like this should do the trick.

class IConfigFactoryBean implements FactoryBean<IConfig> {

    @Autowired
    private IConfigProvider configProvider;

    private IConfig config;

    @PostConstruct
    public void initialize() {
        config = configProvider.getConfig(...);
    }


    @Override
    public IConfig getObject() throws Exception {
        return config;
    }

    @Override
    public Class<?> getObjectType() {
        return ...;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

I am not sure what the argument would be. Note that if you have several instances of IConfig you will need to qualify them as Spring won't be able to know which one it has to inject based on a simple @Autowired annotation. Check the javadoc of @Qualifier for more information.