49 lines
1.5 KiB
Markdown
49 lines
1.5 KiB
Markdown
---
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layout: pattern
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title: Proxy
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folder: proxy
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permalink: /patterns/proxy/
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pumlid: 9SR13OCm30NGLM00udktCS62eCI9x6yesrEfx_Jcehd69c5rEe3X7oBZE-q5HwpXOhahH95oRrHgt0msEldYPHClkow30J5rQko_qB3-VKYG_qjXBOrezGK0
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categories: Structural
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tags:
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- Java
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- Gang Of Four
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- Difficulty-Beginner
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---
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## Also known as
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Surrogate
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## Intent
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Provide a surrogate or placeholder for another object to control
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access to it.
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## Applicability
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Proxy is applicable whenever there is a need for a more
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versatile or sophisticated reference to an object than a simple pointer. Here
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are several common situations in which the Proxy pattern is applicable
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* a remote proxy provides a local representative for an object in a different address space.
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* a virtual proxy creates expensive objects on demand.
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* a protection proxy controls access to the original object. Protection proxies are useful when objects should have different access rights.
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## Typical Use Case
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* control access to another object
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* lazy initialization
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* implement logging
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* facilitate network connection
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* to count references to an object
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## Real world examples
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* [java.lang.reflect.Proxy](http://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Proxy.html)
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* [Apache Commons Proxy](https://commons.apache.org/proper/commons-proxy/)
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* Mocking frameworks Mockito, Powermock, EasyMock
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## Credits
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* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
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