抽象工厂模式

Posted 2020-07-01 Kriskee

　　简单工厂是一个实体类，包含了根据不同参数直接创建对象的方法。而抽象工厂(Abstract Factory pattern)则是在简单工厂的基础上将(多个)工厂类进一步进行抽象(如UML图示)：

　　

　　在工程中，我们创建了两个实体类:动物类(Animal)和植物类(Plant)；这两个类分别遵循协议AnimalProtocol和PlantProtocol；分别有子类Dog、Fish、Bird(继承自Animal类)和Rose、Sakura(继承自Plant类)；这两个实体类分别通过工厂类AnimalFactory和PlantFactory进行实例化(均继承自BioligyFactory工厂类)；在此基础上，将工厂类进一步抽象，通过抽象工厂类AbstractFactory对工厂类进行实例化。

　　代码实现:

　　1.Animal、AnimalFactory、BiologyFactory

　　Animal、AnimalFactory代码在《简单工厂模式》中已经创建，只需要将AnimaFactory继承于BiologyFactory并将类方法改为实例方法即可。

 1 // BiologyFactory.h
 2 #import <Foundation/Foundation.h>
 3 #import "Plant.h"
 4 #import "Animal.h"
 5 
 6 typedef NS_ENUM(NSInteger, EFactory){
 7     kAnimalFactory,
 8     kPlantFactory,
 9 };
10 
11 typedef NS_ENUM(NSInteger, EPlantType){
12     kRose,
13     kSakura,
14 };
15 
16 typedef enum {
17     kDog,
18     kBird,
19     kFish,
20 }EAnimalType;
21 
22 @interface BiologyFactory : NSObject
23 
24 - (Plant*)createPlantWithType:(EPlantType)type;
25 
26 - (Animal*)createAnimalWithType:(EAnimalType)type;
27 
28 @end

　　2.Plant、PlantFactory

 1 // Plant.h
 2 #import <Foundation/Foundation.h>
 3 
 4 @protocol PlantProtocol <NSObject>
 5 @optional
 6 - (void)flower;
 7 - (void)color;
 8 @end
 9 
10 @interface Plant : NSObject<PlantProtocol>
11 
12 @end
13 
14 // Rose.h
15 #import "Plant.h"
16 
17 @interface Rose : Plant
18 
19 - (void)thorn;
20 
21 @end
22 
23 // Sakura.h
24 #import "Plant.h"
25 
26 @interface Sakura : Plant
27 
28 - (void)enjoyFlower;
29 
30 @end

 1 // PlantFactory.h
 2 #import "BiologyFactory.h"
 3 #import "Rose.h"
 4 #import "Sakura.h"
 5 
 6 @interface PlantFactory : BiologyFactory
 7 
 8 - (Plant*)createPlantWithType:(EPlantType)type;
 9 
10 @end
11 
12 // PlantFactory.m
13 #import "PlantFactory.h"
14 
15 @implementation PlantFactory
16 
17 - (Plant *)createPlantWithType:(EPlantType)type{
18     Plant *plant = nil;
19     if(type == kRose){
20         plant = [Rose new];
21     }else if(type == kSakura){
22         plant = [Sakura new];
23     }
24     return plant;
25 }
26 
27 @end

　　3.AbstractFactory创建

 1 // AbstractFactory.h
 2 #import <Foundation/Foundation.h>
 3 #import "BiologyFactory.h"
 4 #import "AnimalFactory.h"
 5 #import "PlantFactory.h"
 6 
 7 @interface AbstractFactory : NSObject
 8 
 9 + (BiologyFactory*)createFactoryWithType:(EFactory)type;
10 
11 @end
12 
13 // AbstractFactory.m
14 #import "AbstractFactory.h"
15 
16 @implementation AbstractFactory
17 
18 + (BiologyFactory*)createFactoryWithType:(EFactory)type{
19     BiologyFactory *factory = nil;
20     if(type == kAnimalFactory){
21         factory = [AnimalFactory new];
22     }else if(type == kPlantFactory){
23         factory = [PlantFactory new];
24     }
25     return factory;
26 }
27 
28 @end