GOF设计模式在Java中的应用实例-优快云博客

原文：http://stackoverflow.com/questions/1673841/examples-of-gof-design-patterns

创建型模式

抽象工厂

单例

结构型模式

适配器 (把一种接口类型转换成另一种接口类型)
- java.util.Arrays#asList()
- java.io.InputStreamReader(InputStream) (returns a Reader)
- java.io.OutputStreamWriter(OutputStream) (returns a Writer)
- javax.xml.bind.annotation.adapters.XmlAdapter#marshal() and #unmarshal()
组合
- java.awt.Container#add(Component) (practically all over Swing thus)
- javax.faces.component.UIComponent#getChildren() (practically all over JSF UI thus)
装饰器
- All subclasses of java.io.InputStream, OutputStream, Reader and Writer have a constructor taking an instance of same type.
- java.util.Collections, the checkedXXX(), synchronizedXXX() and unmodifiableXXX()methods.
- javax.servlet.http.HttpServletRequestWrapper and HttpServletResponseWrapper
Facade (recognizeable by behavioral methods which internally uses instances of different independent abstract/interface types)
- javax.faces.context.FacesContext, it internally uses among others the abstract/interface typesLifeCycle, ViewHandler, NavigationHandler and many more without that the enduser has to worry about it (which are however overrideable by injection).
- javax.faces.context.ExternalContext, which internally uses ServletContext, HttpSession, HttpServletRequest, HttpServletResponse, etc.
Flyweight (recognizeable by creational methods returning a cached instance, a bit the "multiton" idea)
- java.lang.Integer#valueOf(int) (also on Boolean, Byte, Character, Short and Long)
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)
- java.lang.reflect.Proxy
- java.rmi.*, the whole API actually.
Behavioral patterns

Chain of responsibility (recognizeable by behavioral methods which (indirectly) invokes the same method inanother implementation of same abstract/interface type in a queue)
- java.util.logging.Logger#log()
- javax.servlet.Filter#doFilter()
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)
- All implementations of java.lang.Runnable
- All implementations of javax.swing.Action
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)
- java.util.Pattern
- java.text.Normalizer
- All subclasses of java.text.Format
- All subclasses of javax.el.ELResolver
Iterator (recognizeable by behavioral methods sequentially returning instances of a different type from a queue)
- All implementations of java.util.Iterator (thus among others also java.util.Scanner!).
- All implementations of java.util.Enumeration
Mediator (recognizeable by behavioral methods taking an instance of different abstract/interface type (usually using the command pattern) which delegates/uses the given instance)
- java.util.Timer (all scheduleXXX() methods)
- java.util.concurrent.Executor#execute()
- java.util.concurrent.ExecutorService (the invokeXXX() and submit() methods)
- java.util.concurrent.ScheduledExecutorService (all scheduleXXX() methods)
- java.lang.reflect.Method#invoke()
Memento (recognizeable by behavioral methods which internally changes the state of the whole instance)
- java.util.Date (the setter methods do that, Date is internally represented by a long value)
- All implementations of java.io.Serializable
- All implementations of javax.faces.component.StateHolder
Observer (or Publish/Subscribe) (recognizeable by behavioral methods which invokes a method on an instance of another abstract/interface type, depending on own state)
- java.util.Observer/java.util.Observable (rarely used in real world though)
- All implementations of java.util.EventListener (practically all over Swing thus)
- javax.servlet.http.HttpSessionBindingListener
- javax.servlet.http.HttpSessionAttributeListener
- javax.faces.event.PhaseListener
State (recognizeable by behavioral methods which changes its behaviour depending on the instance's state which can be controlled externally)
- javax.faces.lifecycle.LifeCycle#execute() (controlled by FacesServlet, the behaviour is dependent on current phase (state) of JSF lifecycle)
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)
- java.util.Comparator#compare(), executed by among others Collections#sort().
- javax.servlet.http.HttpServlet, the service() and all doXXX() methods take HttpServletRequest and HttpServletResponse and the implementor has to process them (and not to get hold of them as instance variables!).
- javax.servlet.Filter#doFilter()
Template method (recognizeable by behavioral methods which already have a "default" behaviour definied by an abstract type)
- All non-abstract methods of java.io.InputStream, java.io.OutputStream, java.io.Readerand java.io.Writer.
- All non-abstract methods of java.util.AbstractList, java.util.AbstractSet and java.util.AbstractMap.
- javax.servlet.http.HttpServlet, all the doXXX() methods by default sends a HTTP 405 "Method Not Allowed" error to the response. You're free to implement none or any of them.
Visitor (recognizeable by two different abstract/interface types which has methods definied which takes each theother abstract/interface type; the one actually calls the method of the other and the other executes the desired strategy on it)

JDK中的设计模式

原文：http://stackoverflow.com/questions/1673841/examples-of-gof-design-patterns

创建型模式

抽象工厂

Builder

工厂方法

原型

单例

适配器 (把一种接口类型转换成另一种接口类型)

组合

装饰器

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)

Behavioral patterns

Chain of responsibility (recognizeable by behavioral methods which (indirectly) invokes the same method inanother 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 theother abstract/interface type; the one actually calls the method of the other and the other executes the desired strategy on it)

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