Static Class Structure

• Client
  • Refers to the Component interface.
• Component
  • Defines a common interface for Component1 and Decorator objects.
• Component1
  • Defines objects that get decorated.
• Decorator
  • Maintains a reference to a Component object (component).
  • Forwards requests to this component (component.operation()).
• Decorator1,Decorator2,…
  • Implement additional functionality (addBehavior()) to be performed before and/or after forwarding a request.

Dynamic Object Collaboration

• In this sample scenario, a Client object works through two decorators that add responsibilities to a Component1 object.
• The Client calls operation() on the Decorator1 object.
• Decorator1 forwards the request to the Decorator2 object.
• Decorator2 forwards the request to the Component1 object.
• Component1 performs the request and returns to Decorator2.
• Decorator2 performs additional functionality (by calling addBehavior() on itself) and returns to Decorator1.
• Decorator1 performs additional functionality and returns to the Client.
• See also Sample Code / Example 1.