Java design Pattern 2--abstract Factory mode (Factory)

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Abstract Factory mode (alias: Package)

Provides an interface to create a series of (interdependent) objects without specifying their specific classes.

Overview

Abstract Factory method patterns can be used to design a system when the system is ready to provide a series of related objects to the user and does not want to create a coupling between user code and the class that creates the objects. The key to an abstract factory pattern is to define several abstract methods in an abstract class or interface that return an instance of a class, which allows its subclasses or classes that implement the interface to override these abstract methods to provide a series of related objects to the user.

Applicability

1. A system is independent of the creation, composition, and presentation of its products.

2. When a system is to be configured by one of multiple product families.

3. When you want to emphasize the design of a series of related product objects for joint use.

4. When you provide a Product class library and just want to display their interfaces instead of implementing them.

Participants

1.AbstractFactory declares an operation interface that creates an abstract product object.

2.ConcreteFactory implements the operation of creating a specific product object.

3.AbstractProduct declares an interface for a class of product objects.

4.ConcreteProduct defines a product object that will be created by the corresponding specific factory. Implements the Abstractproduct interface.

5.Client use only interfaces declared by the Abstractfactory and Abstractproduct classes

Structure and use of abstract factory pattern

The structure of the pattern consists of four roles:

• Abstract products (prodcut)

• Specific Products (concreteproduct)

• Abstract Factory (abstractfactory)

• Specific Factory (concretefactory)

UML Class diagrams for schemas

Actual combat part

Example 1: Establish a system that provides users with a suit (top + trousers) and a denim set (top + trousers).

Description and use of the structure of the pattern

1. Abstract (product):

Upperclothes.java

 Public Abstract class upperclothes{   publicabstractint  getchestsize ();     Public Abstract int getheight ();     Public Abstract String getName ();}

Trousers.java

 Public Abstract class trousers{   publicabstractint  getwaistsize ();     Public Abstract int getheight ();     Public Abstract String getName ();}

2. Specific products (concreteproduct) _1: Westernupperclothes.java

 Public classWesternupperclothesextendsupperclothes{Private intchestsize; Private intheight; PrivateString name; Westernupperclothes (String name,intChestsize,intheight) {        This. name=name;  This. chestsize=chestsize;  This. height=height; }    Public intgetchestsize () {returnchestsize; }    Public intgetheight () {returnheight; }    PublicString GetName () {returnname; } }

2. Specific products (concreteproduct) _2: Cowboyupperclothes.java

 Public classCowboyupperclothesextendsupperclothes{Private intchestsize; Private intheight; PrivateString name; Cowboyupperclothes (String name,intChestsize,intheight) {        This. name=name;  This. chestsize=chestsize;  This. height=height; }    Public intgetchestsize () {returnchestsize; }    Public intgetheight () {returnheight; }    PublicString GetName () {returnname; } }

2. Specific products (concreteproduct) _3: Westerntrousers.java

 Public classWesterntrousersextendstrousers{Private intwaistsize; Private intheight; PrivateString name; Westerntrousers (String name,intWaistsize,intheight) {        This. name=name;  This. waistsize=waistsize;  This. height=height; }     Public intgetwaistsize () {returnwaistsize; }    Public intgetheight () {returnheight; }    PublicString GetName () {returnname; } }

2. Specific products (concreteproduct) _4: Cowboytrousers.java

 Public classCowboytrousersextendstrousers{Private intwaistsize; Private intheight; PrivateString name; Cowboytrousers (String name,intWaistsize,intheight) {        This. name=name;  This. waistsize=waistsize;  This. height=height; }     Public intgetwaistsize () {returnwaistsize; }    Public intgetheight () {returnheight; }    PublicString GetName () {returnname; } }

3. Abstract Factory (abstractfactory): Clothesfactory.java

 Public Abstract class clothesfactory{    publicabstract upperclothes createupperclothes (int chestsize,int  height);      Public Abstract Trousers createtrousers (int waistsize,int  height);}

4. Specific Factory (concretefactory): Beijingclothesfactory.java

 Public classBeijingclothesfactoryextendsClothesfactory { PublicUpperclothes Createupperclothes (intChestsize,intheight) {         return NewWesternupperclothes ("Beijing brand suit Top", Chestsize,height); }     PublicTrousers Createtrousers (intWaistsize,intheight) {         return NewWesterntrousers ("Beijing Brand Suit Pants", Waistsize,height); }}

Shanghaiclothesfactory.java

 Public classShanghaiclothesfactoryextendsClothesfactory { PublicUpperclothes Createupperclothes (intChestsize,intheight) {         return NewWesternupperclothes ("Shanghai brand Denim Shirt", Chestsize,height); }     PublicTrousers Createtrousers (intWaistsize,intheight) {         return NewWesterntrousers ("Shanghai Brand Jeans", Waistsize,height); }}

5. Application _1: Shop.java

 Public classshop{upperclothes cloth;     Trousers Trouser;  Public voidGivesuit (Clothesfactory Factory,intChestsize,intWaistsize,intheight) {Cloth=factory.createupperclothes (chestsize,height); Trouser=factory.createtrousers (waistsize,height);    Showmess (); }    Private voidshowmess () {System.out.println ("< set info >"); System.out.println (Cloth.getname ()+":"); System.out.print ("Bust:" +cloth.getchestsize ()); System.out.println ("Height:" +cloth.getheight ()); System.out.println (Trouser.getname ()+":"); System.out.print ("Waist:" +trouser.getwaistsize ()); System.out.println ("Height:" +trouser.getheight ()); }}

5. Application _2: Application.java

 Public class application{    publicstaticvoid  main (String args[]) {        shop Shop =New shop ();       Clothesfactory Factory=new  beijingclothesfactory ();        Shop.givesuit (Factory,110,82,170);       Factory=new  shanghaiclothesfactory ();        Shop.givesuit (Factory,120,88,180);}    }

Advantages of the abstract factory model

• Abstract Factory mode creates a series of related objects for the user to decouple the user from the class that created the objects.

• Use abstract Factory mode to easily configure a range of objects for your users. Users can get a set of related objects using different factories, and also avoid mixing objects in different series.

• In abstract Factory mode, a "specific factory" can be added at any time to provide users with a set of related objects.

Java design Pattern 2--abstract Factory mode (Factory)