layout	pattern
title	Proxy
folder	proxy
permalink	/patterns/proxy/
pumlid	9SR13OCm30NGLM00udktCS62eCI9x6yesrEfx_Jcehd69c5rEe3X7oBZE-q5HwpXOhahH95oRrHgt0msEldYPHClkow30J5rQko_qB3-VKYG_qjXBOrezGK0
categories	Structural
tags	Java Gang Of Four Difficulty-Beginner

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

• Remote proxy provides a local representative for an object in a different address space.
• Virtual proxy creates expensive objects on demand.
• 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
• Count references to an object

Tutorials

• Controlling Access With Proxy Pattern

Presentations

• Proxy

Real world examples

• java.lang.reflect.Proxy
• Apache Commons Proxy
• Mocking frameworks Mockito, Powermock, EasyMock

Credits

• Design Patterns: Elements of Reusable Object-Oriented Software