Proxy vs. Decorator Pattern

Proxy and Decorator both wrap an object and expose the same interface. The difference is why the wrapper exists.

Proxy

Proxy exists to control access to the real object:

• delay creation
• enforce permissions
• represent remoteness
• monitor or cache access

Decorator

Decorator exists to add behavior around a component:

• logging
• formatting
• enrichment
• optional features

Java Shortcut

Ask:

• “Am I controlling access to the real thing?” -> Proxy
• “Am I layering optional behavior around the same contract?” -> Decorator

Some wrappers resemble both. When that happens, decide which concern is primary and name the abstraction accordingly.