Also known as: Surrogate

Intent: Provide a surrogate or placeholder for another object to control access to it.

Applicability: Proxy is applicable whenever there is a need for a more versatile or sophisticated reference to an object than a simple pointer. Here are several common situations in which the Proxy pattern is applicable

• a remote proxy provides a local representative for an object in a different address space.
• a virtual proxy creates expensive objects on demand.
• a protection proxy controls access to the original object. Protection proxies are useful when objects should have different access rights.

Typical Use Case:

• control access to another object
• lazy initialization
• implement logging
• facilitate network connection
• to count references to an object

Real world examples:

• java.lang.reflect.Proxy
• Apache Commons Proxy

Credits

• Design Patterns: Elements of Reusable Object-Oriented Software