Examples of GoF Design Patterns in Java's core ...

Stella981
• 阅读 592

+250

You can find an overview of a lot design patterns in Wikipedia. It also mentions which patterns are mentioned by GoF. I'll sum them up here and try to assign as much as possible pattern implementations found in both the Java SE and Java EE API's.

Creational patterns

Abstract factory (recognizeable by creational methods returning an abstract/interface type)

Builder (recognizeable by creational methods returning the instance itself)

Factory method (recognizeable by creational methods returning a concrete type)

Prototype (recognizeable by creational methods returning a different instance of itself with the same properties)

Singleton (recognizeable by creational methods returning the same instance (usually of itself) everytime)

Structural patterns

Adapter (recognizeable by creational methods taking an instance of different abstract/interface type and returning an implementation of own/another abstract/interface type which decorates/overrides the given instance)

Bridge (recognizeable by creational methods taking an instance of different abstract/interface type and returning an implementation of own abstract/interface type which delegates/uses the given instance)

  • None comes to mind yet. A fictive example would be new LinkedHashMap(LinkedHashSet<K>, List<V>) which returns an unmodifiable linked map which doesn't clone the items, but uses them. The java.util.Collections#newSetFromMap() and singletonXXX() methods however comes close.

Composite (recognizeable by behavioral methods taking an instance of same abstract/interface type into a tree structure)

Decorator (recognizeable by creational methods taking an instance of same abstract/interface type which adds additional behaviour)

Facade (recognizeable by behavioral methods which internally uses instances of different independent abstract/interface types)

Flyweight (recognizeable by creational methods returning a cached instance, a bit the "multiton" idea)

Proxy (recognizeable by creational methods which returns an implementation of given abstract/interface type which in turn delegates/uses a different implementation of given abstract/interface type)

The Wikipedia example is IMHO a bit poor, lazy loading has actually completely nothing to do with the proxy pattern at all.

Behavioral patterns

Chain of responsibility (recognizeable by behavioral methods which (indirectly) invokes the same method in another implementation of same abstract/interface type in a queue)

Command (recognizeable by behavioral methods in an abstract/interface type which invokes a method in an implementation of a different abstract/interface type which has been encapsulated by the command implementation during its creation)

Interpreter (recognizeable by behavioral methods returning a structurally different instance/type of the given instance/type; note that parsing/formatting is not part of the pattern, determining the pattern and how to apply it is)

Iterator (recognizeable by behavioral methods sequentially returning instances of a different type from a queue)

Mediator (recognizeable by behavioral methods taking an instance of different abstract/interface type (usually using the command pattern) which delegates/uses the given instance)

Memento (recognizeable by behavioral methods which internally changes the state of the whole instance)

Observer (or Publish/Subscribe) (recognizeable by behavioral methods which invokes a method on an instance of another abstract/interface type, depending on own state)

State (recognizeable by behavioral methods which changes its behaviour depending on the instance's state which can be controlled externally)

Strategy (recognizeable by behavioral methods in an abstract/interface type which invokes a method in an implementation of a different abstract/interface type which has been passed-in as method argument into the strategy implementation)

Template method (recognizeable by behavioral methods which already have a "default" behaviour definied by an abstract type)

Visitor (recognizeable by two different abstract/interface types which has methods definied which takes each the other abstract/interface type; the one actually calls the method of the other and the other executes the desired strategy on it)

点赞
收藏
评论区
推荐文章
待兔 待兔
5个月前
手写Java HashMap源码
HashMap的使用教程HashMap的使用教程HashMap的使用教程HashMap的使用教程HashMap的使用教程22
Stella981 Stella981
3年前
Cross
https://en.wikipedia.org/wiki/Crosssite\_scripting(https://www.oschina.net/action/GoToLink?urlhttps%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCrosssite_scripting)Definition
Stella981 Stella981
3年前
Spring MVC防御CSRF、XSS和SQL注入攻击
说说CSRF对CSRF(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCrosssite_request_forgery)来说,其实Spring3.1(https://www.oschina.net/acti
Stella981 Stella981
3年前
PostgreSQL是不是你的下一个JSON数据库?
根据Betteridge(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBetteridge%2527s_law_of_headlines)定律(任何头条的设问句可以用一个词来回答:不是),除非你的JSON数据很少修改,并且查询很多。
Wesley13 Wesley13
3年前
P2P技术揭秘.P2P网络技术原理与典型系统开发
Modular.Java(2009.06)\.Craig.Walls.文字版.pdf:http://www.t00y.com/file/59501950(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fwww.t00y.com%2Ffile%2F59501950)\More.E
Stella981 Stella981
3年前
Connect4 Game
Howthisgameisplayecanbefoundathere(https://www.oschina.net/action/GoToLink?urlhttps%3A%2F%2Fen.wikipedia.org%2Fwiki%2FConnect_Four).1publicclassConnect4{
Easter79 Easter79
3年前
Trie 的原理和实现 (python 实现)
原理:(fromwiki)Incomputerscience(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fen.wikipedia.org%2Fwiki%2FComputer_science),atrie,orprefixtree,isano
Stella981 Stella981
3年前
Django资源大全
资源(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fvik.haoluobo.com%2Ftrac%2Fwiki%2FDjango%23%25E8%25B5%2584%25E6%25BA%2590)
Stella981 Stella981
3年前
LeetCode 75. Sort Colors (颜色分类):三路快排
Givenanarraywith _n_ objectscoloredred,whiteorblue,sortthem inplace(https://www.oschina.net/action/GoToLink?urlhttps%3A%2F%2Fen.wikipedia.org%2Fwiki%2FInplace_algori
Stella981 Stella981
3年前
Primary market
The primarymarket isthepartofthe capitalmarket(https://www.oschina.net/action/GoToLink?urlhttp%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCapital_market) thatdealswithissuin