Sling Adapters

Sling AdaptTo :

Sling offers an Adapter pattern to conveniently translate objects that implement the Adaptable interface. This interface provides a generic adaptTo() method that will translate the object to the class type being passed as the argument.

For example to translate a Resource object to the corresponding Node object, you can simply do:

Example : Node node = resource.adaptTo(Node.class);

Use Cases :

There are the following use cases:

• Get implementation-specific objects.For example, a JCR-based implementation of the generic Resource interface provides access to the underlying JCR Node.
• Shortcut creation of objects that require internal context objects to be passed.For example, the JCR-based ResourceResolver holds a reference to the request's JCR Session, which in turn is needed for many objects that will work based on that request session, such as the PageManager or UserManager.
• Shortcut to services.A rare case - sling.getService() is simple as well.

How it works :

There are various ways that Adaptable.adaptTo() can be implemented:

• By the object itself; implementing the method itself and mapping to certain objects.
• By an AdapterFactory, which can map arbitrary objects.
• The objects must still implement the Adaptable interface and must extend SlingAdaptable (which passes the adaptTo call to a central adapter manager).
• This allows hooks into the adaptTo mechanism for existing classes, such as Resource.

Reference : Sling Adapters.