［Objective-C 设计模式］简单工厂模式

写代码已经写了5年多了，自从开始写代码的时候，就买了本《大话设计模式》在研究，当时对设计模式还不是很明白，经过这么多年的沉淀，感觉对设计模式也有一些心得，但是最近不知道为何，感觉自己写的代码还是不够好，没有达到真正的面相对象开发，所以现在重新温习一下设计模式，看看能不能有一些新的体会，让我的代码能够更健壮，更加易于扩展，能更好的抵抗策划多变的需求。也随便学习一下Objective－C语言（一直想学习这么语言，但是无奈于闲暇时间太少。）

简单工厂模式

简单工厂模式又称之为静态工厂方法，属于创建型模式。在简单工厂模式中，可以根据传递的参数不同，返回不同类的实例。简单工厂模式定义了一个类，这个类专门用于创建其他类的实例，这些被创建的类都有一个共同的父类。

简单工厂模式将对象的创建和对象本身业务处理分离了，可以降低系统的耦合度，使得两者修改起来都相对容易些。当以后实现改变时，只需要修改工厂类即可。

优点：

1、简单工厂模式实现了对责任的分割，提供了专门的工厂类用于创建对象。

2、客户端无须知道所创建的具体产品类的类名，只需要知道具体产品类所对应的参数即可，对于一些复杂的类名，通过简单工厂模式可以减少使用者的记忆量。

3、通过引入配置文件，可以在不修改任何客户端代码的情况下更换和增加新的具体产品类，在一定程度上提高了系统的灵活性。

缺点：

1、使用简单工厂模式将会增加系统中类的个数，在一定程序上增加了系统的复杂度和理解难度。

2、系统扩展困难，一旦添加新产品就不得不修改工厂逻辑，在产品类型较多时，有可能造成工厂逻辑过于复杂，不利于系统的扩展和维护。

项目地址：https://github.com/GameRisker/Study-Design-Patterns.git

//
//  main.m
//  SimpleFactory
//  简单工厂模式
//
//  Created by GameRisker on 15/12/4.
//  Copyright (c) 2015年 GameRisker. All rights reserved.
//

#import "Operation.h"
#import "OperationFactory.h"
#import <Foundation/Foundation.h>
int main(int argc, const char* argv[])
{
    @autoreleasepool
    {
        // insert code here...
        Operation* opera = [OperationFactory createOpetation:@"+"];
        opera.numberA = 100;
        opera.numberB = 99;
        NSLog(@"result is %ld", [opera GetResult]);
        
        
        opera = [OperationFactory createOpetation:@"-"];
        opera.numberA = 10;
        opera.numberB = 9;
        NSLog(@"result is %ld", [opera GetResult]);

        opera = [OperationFactory createOpetation:@"*"];
        opera.numberA = 200;
        opera.numberB = 33;
        NSLog(@"result is %ld", [opera GetResult]);

        opera = [OperationFactory createOpetation:@"/"];
        opera.numberA = 666;
        opera.numberB = 44;
        NSLog(@"result is %ld", [opera GetResult]);

    }
    return 0;
}

// main.m

// SimpleFactory

// 简单工厂模式

// Created by GameRisker on 15/12/4.

#import "Operation.h"

#import "OperationFactory.h"

#import <Foundation/Foundation.h>

int main(int argc, const char* argv[])

{

@autoreleasepool

{

// insert code here...

Operation* opera = [OperationFactory createOpetation:@"+"];

opera.numberA = 100;

opera.numberB = 99;

NSLog(@"result is %ld", [opera GetResult]);

opera = [OperationFactory createOpetation:@"-"];

opera.numberA = 10;

opera.numberB = 9;

NSLog(@"result is %ld", [opera GetResult]);

opera = [OperationFactory createOpetation:@"*"];

opera.numberA = 200;

opera.numberB = 33;

NSLog(@"result is %ld", [opera GetResult]);

opera = [OperationFactory createOpetation:@"/"];

opera.numberA = 666;

opera.numberB = 44;

NSLog(@"result is %ld", [opera GetResult]);

}

return 0;

}

//
//  Operation.h
//
//
//  Created by GameRisker on 15/12/4.
//
//

#import <Foundation/Foundation.h>



@interface Operation : NSObject

@property (readwrite ,assign) long numberA;
@property (readwrite ,assign) long numberB;

- (long)GetResult;

@end

// Operation.h

// Created by GameRisker on 15/12/4.

#import <Foundation/Foundation.h>

@interface Operation : NSObject

@property (readwrite ,assign) long numberA;

@property (readwrite ,assign) long numberB;

- (long)GetResult;

@end

//
//  Operation.m
//
//
//  Created by GameRisker on 15/12/4.
//
//

#import "Operation.h"

@implementation Operation

- (long)GetResult
{
    return 0;
}

@end

// Operation.m

// Created by GameRisker on 15/12/4.

#import "Operation.h"

@implementation Operation

- (long)GetResult

{

return 0;

}

@end

//
//  OperationFactory.h
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import <Foundation/Foundation.h>

@interface OperationFactory : NSObject

+ (Operation*)createOpetation:(NSString*)operation;

@end

// OperationFactory.h

// Created by GameRisker on 15/12/5.

#import <Foundation/Foundation.h>

@interface OperationFactory : NSObject

+ (Operation*)createOpetation:(NSString*)operation;

@end

//
//  OperationFactory.m
//
//
//  Created by GameRisker on 15/12/5.
//
//

#import "Operation.h"
#import "OperationAdd.h"
#import "OperationDiv.h"
#import "OperationFactory.h"
#import "OperationMul.h"
#import "OperationSub.h"

@implementation OperationFactory

+ (Operation*)createOpetation:(NSString*)operation
{
    NSLog(@"createOperation : %@", operation);

    Operation* opera;
    if ([operation isEqualToString:@"+"]) {
        opera = [[OperationAdd alloc] init];
    }
    else if ([operation isEqualToString:@"-"]) {
        opera = [[OperationSub alloc] init];
    }
    else if ([operation isEqualToString:@"*"]) {
        opera = [[OperationMul alloc] init];
    }
    else if ([operation isEqualToString:@"/"]) {
        opera = [[OperationDiv alloc] init];
    }

    return opera;
}
@end

// OperationFactory.m

// Created by GameRisker on 15/12/5.

#import "Operation.h"

#import "OperationAdd.h"

#import "OperationDiv.h"

#import "OperationFactory.h"

#import "OperationMul.h"

#import "OperationSub.h"

@implementation OperationFactory

+ (Operation*)createOpetation:(NSString*)operation

{

NSLog(@"createOperation : %@", operation);

Operation* opera;

if ([operation isEqualToString:@"+"]) {

opera = [[OperationAdd alloc] init];

}

else if ([operation isEqualToString:@"-"]) {

opera = [[OperationSub alloc] init];

}

else if ([operation isEqualToString:@"*"]) {

opera = [[OperationMul alloc] init];

}

else if ([operation isEqualToString:@"/"]) {

opera = [[OperationDiv alloc] init];

}

return opera;

}

@end

//
//  OperationAdd.h
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "Operation.h"

@interface OperationAdd : Operation

@end

// OperationAdd.h

// Created by GameRisker on 15/12/5.

#import "Operation.h"

@interface OperationAdd : Operation

@end

//
//  OperationAdd.m
//
//
//  Created by GameRisker on 15/12/5.
//
//

#import "OperationAdd.h"

@implementation OperationAdd

- (long)GetResult
{
    long result = 0;
    result = self.numberA + self.numberB;
    return result;
}
@end

// OperationAdd.m

// Created by GameRisker on 15/12/5.

#import "OperationAdd.h"

@implementation OperationAdd

- (long)GetResult

{

long result = 0;

result = self.numberA + self.numberB;

return result;

}

@end

//
//  OperationSub.h
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "Operation.h"

@interface OperationSub : Operation

@end

// OperationSub.h

// Created by GameRisker on 15/12/5.

#import "Operation.h"

@interface OperationSub : Operation

@end

//
//  OperationSub.m
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "OperationSub.h"

@implementation OperationSub

-(long) GetResult
{
    return self.numberA - self.numberB;
}
@end

// OperationSub.m

// Created by GameRisker on 15/12/5.

#import "OperationSub.h"

@implementation OperationSub

-(long) GetResult

{

return self.numberA - self.numberB;

}

@end

//
//  OperationMul.h
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "Operation.h"

@interface OperationMul : Operation

@end

// OperationMul.h

// Created by GameRisker on 15/12/5.

#import "Operation.h"

@interface OperationMul : Operation

@end

//
//  OperationMul.m
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "OperationMul.h"

@implementation OperationMul
-(long) GetResult
{
    return self.numberA * self.numberB;
}
@end

// OperationMul.m

// Created by GameRisker on 15/12/5.

#import "OperationMul.h"

@implementation OperationMul

-(long) GetResult

{

return self.numberA * self.numberB;

}

@end

//
//  OperationDiv.h
//  
//
//  Created by GameRisker on 15/12/5.
//
//

#import "Operation.h"

@interface OperationDiv : Operation

@end

// OperationDiv.h

// Created by GameRisker on 15/12/5.

#import "Operation.h"

@interface OperationDiv : Operation

@end

//
//  OperationDiv.m
//
//
//  Created by GameRisker on 15/12/5.
//
//

#import "OperationDiv.h"

@implementation OperationDiv

- (long)GetResult
{
    if (self.numberB == 0) {
        NSLog(@"numberB is zero!");
        return 0;
    }
    return self.numberA / self.numberB;
}
@end

// OperationDiv.m

// Created by GameRisker on 15/12/5.

#import "OperationDiv.h"

@implementation OperationDiv

- (long)GetResult

{

if (self.numberB == 0) {

NSLog(@"numberB is zero!");

return 0;

}

return self.numberA / self.numberB;

}

@end

参考：http://www.cnblogs.com/chenssy/（Java 版本）

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［Objective-C 设计模式］简单工厂模式

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