How to inject Spring Bean for factory method requiring MyClass.class parameter

Question

I'm trying to inject a java.util.prefs.Preferences bean in to my master controller. The controller looks like:

@Controller
class MyController {
    @Autowired
    private Preferences preferences;
}

The application-context.xml file creates the bean for java.util.prefs.Preferences. It uses a factory method so I have the following entry for creating the bean:

<bean id="preferences" class="java.util.prefs.Preferences" factory-method="userNodeForPackage" />

Preferences.userNodeForPackage(param) takes for a parameter the class related to the Preference. In this case Spring needs to create the bean by performing the call:

Preferences.userNodeForPackage(MyController.class);

How can a class be passed in to a spring bean instantiated with a factory method? Thanks

Environment information:

Java 7
Spring 3.1

Answer 1

You can specify the constructor-arg element

<bean id="preferences" class="java.util.prefs.Preferences" factory-method="userNodeForPackage">
    <constructor-arg type="java.lang.Class" value="com.path.MyController" />
</bean>

This is explained in the official documentation here, section 5.4.1.

Arguments to the static factory method are supplied via elements, exactly the same as if a constructor had actually been used. The type of the class being returned by the factory method does not have to be of the same type as the class that contains the static factory method, although in this example it is. An instance (non-static) factory method would be used in an essentially identical fashion (aside from the use of the factory-bean attribute instead of the class attribute), so details will not be discussed here.

Answer 2

Well I don't know the xml based configuration way but I can tell you how you can instantiate it via Configuration class.

@Configuration
public class Config {
    @Bean(name="preferences")
    public java.util.prefs.Preferences preferences() {
        // init
        return java.util.prefs.Preferences.userNodeForPackage(YourExpectedClass.class);
    }
}

P.S. :

You will need to add your configuration class/package for scanning either in web.xml if you are using complete annotation based approach [contextClass=org.springframework.web.context.support.AnnotationConfigWebApplicationContext] or in your config file as below :

<context:component-scan base-package="com.comp.prod.conf" />