Spring Social's ConnectController works with one or more provider-specific ConnectionFactorys to exchange authorization details with the provider and to create connections. Spring Social Facebook provides FacebookConnectionFactory, a ConnectionFactory for creating connections with Facebook.

So that ConnectController can find FacebookConnectionFactory, it must be registered with a ConnectionFactoryRegistry. The following class constructs a ConnectionFactoryRegistry containing a ConnectionFactory for Facebook using Spring's Java configuration style:

@Configuration
public class SocialConfig {
	
    @Bean
    public ConnectionFactoryLocator connectionFactoryLocator() {
        ConnectionFactoryRegistry registry = new ConnectionFactoryRegistry();
        registry.addConnectionFactory(new FacebookConnectionFactory(
            environment.getProperty("facebook.clientId"),
            environment.getProperty("facebook.clientSecret")));
        return registry;
    }

}

Here, a Facebook connection factory is registered with ConnectionFactoryRegistry via the addConnectionFactory() method. If we wanted to add support for connecting to other providers, we would simply register their connection factories here in the same way as FacebookConnectionFactory.

Because client IDs and secrets may be different across environments (e.g., test, production, etc) it is recommended that these values be externalized. As shown here, Spring 3.1's Environment is used to look up the application's client ID and secret.

Optionally, you may also configure ConnectionFactoryRegistry and FacebookConnectionFactory in XML:

<bean id="connectionFactoryLocator" class="org.springframework.social.connect.support.ConnectionFactoryRegistry">
    <property name="connectionFactories">
        <list>
            <bean class="org.springframework.social.facebook.connect.FacebookConnectionFactory">
                <constructor-arg value="${facebook.clientId}" />
                <constructor-arg value="${facebook.clientSecret}" />				
            </bean>
        </list>
    </property>
</bean>
	

This is functionally equivalent to the Java-based configuration of ConnectionFactoryRegistry shown before. The only casual difference is that the connection factories are injected as a list into the connectionFactories property rather than with the addConnectionFactory() method. As in the Java-based configuration, the application's client ID and secret are externalized (shown here as property placeholders).

Refer to Spring Social's reference documentation for complete details on configuring ConnectController and its dependencies.