簡(jiǎn)單工廠模式
正如此模式的名稱一樣，簡(jiǎn)單工廠模式基本上是所有設(shè)計(jì)模式里最簡(jiǎn)單的一種，類與類之間的關(guān)系一目了然。這次我就用很多地方經(jīng)常舉的例子－－計(jì)算器，來說明這個(gè)模式。首先給大家展示一下類之間的結(jié)構(gòu)圖：
通過這張結(jié)構(gòu)圖，可以清晰的看到，加法類、減法類、乘法類、除法類繼承自運(yùn)算類，簡(jiǎn)單工廠類依賴于運(yùn)算類的實(shí)例化來實(shí)現(xiàn)相應(yīng)的運(yùn)算功能，好的，看起來并不復(fù)雜，讓我們直接展示一下代碼吧(鑒于目前點(diǎn)點(diǎn)不支持Objective C的代碼高亮，所以就直接寫啦，盡量保持整齊吧。另，為了照顧像我一樣基礎(chǔ)不是很好的同學(xué)，我盡量把代碼寫全，方便大家調(diào)試)。
注意：本文所有代碼均在ARC環(huán)境下編譯通過。
首先是運(yùn)算類（父類）：
接口文件：
@interface Operation :NSObject{
double numberA;
double numberB;
}
@property double numberA;
@property double numberB;
-(double) GetResult;
@end
@implementation Operation
@synthesize numberA, numberB;
-(double) GetResult{
return -1.0; //此處默認(rèn)返回-1.0，無其他意義
}
@end
@interface OperationAdd:Operation
@end
@implementation OperationAdd
-(double) GetResult{
double result =0;
result =numberA+numberB;
return result;
}
@end
@implementation OperationSub
-(double)GetResult{
double result =0;
result = numberA-numberB;
return result;
}
@end
@implementation OperationMul
-(double)GetResult{
double result =0;
result = numberA*numberB;
return result;
}
@end
@interface OperationDiv:Operation
@end
@implementation OperationDiv
-(double)GetResult{
double result =0;
@try{
result = numberA/numberB;
}
@catch(NSException *exception) {
NSLog(@"除數(shù)不能為0");
}
return result;
}
@end
@interface OperationFactory:NSObject
+(Operation*)CreateOperate:(char)operate;
@end
+(Operation*)CreateOperate:(char)operate{
Operation *oper;
switch(operate) {
case '+':
oper = [[OperationAdd alloc]init];
break;
case '-':
oper = [[OperationSub alloc]init];
break;
case '*':
oper = [[OperationMul alloc]init];
break;
case '/':
oper = [[OperationDiv alloc]init];
break;
default:
oper = nil;
break;
}
return oper;
}
int main (int argc,const char* argv[])
{
@autoreleasepool{
Operation *oper = [OperationFactory CreateOperate:'*'];
[oper setNumberA:1];
[oper setNumberB:2];
double result = 0;
result = [oper GetResult];
NSLog(@"Result is %f", result);
}
return 0;
}
工廠方法模式
上面關(guān)于簡(jiǎn)單工廠模式中就有提到過一次關(guān)于“工廠類”模式。為了幫助大家能夠回憶一下簡(jiǎn)單工廠模式，在這里提一下簡(jiǎn)單工廠模式的優(yōu)點(diǎn)，簡(jiǎn)單工廠模式的最大優(yōu)點(diǎn)在于工廠類中包含了必要的邏輯判斷，根據(jù)客戶端的選擇條件動(dòng)態(tài)實(shí)例化相關(guān)的類，對(duì)于客戶端來說，去除了與具體產(chǎn)品的依賴。其實(shí)，工廠方法模式是簡(jiǎn)單工廠模式的進(jìn)一步抽象和推廣。由于使用了多態(tài)性，工廠方法模式保持了簡(jiǎn)單工廠模式的優(yōu)點(diǎn)，而且克服了它的缺點(diǎn)。但缺點(diǎn)是，由于每加一個(gè)產(chǎn)品，就需要加一個(gè)產(chǎn)品工廠的類，增加了額外的開發(fā)量。
下面還是以計(jì)算器為例子，詳細(xì)介紹工廠方法模式，還是老樣子，先向大家展示一下類結(jié)構(gòu)圖。
上面這張圖向大家展示了各個(gè)類之間的關(guān)系。其實(shí)和簡(jiǎn)單工廠模式不同的是，類圖的右邊抽象工廠接口是相比簡(jiǎn)單工廠模式多出來的抽象接口。
下面直接上代碼吧，別的不多說了。
注意：本文所有代碼均在ARC環(huán)境下編譯通過。
Operation類接口
@interface Operation :NSObject{
double numberA;
double numberB;
}
@property double numberA;
@property double numberB;
-(double) GetResult;
@end
@implementation Operation
@synthesize numberA, numberB;
-(double) GetResult{
return -1.0;
}
@end
@interface OperationAdd :Operation
@end
@implementation OperationAdd
-(double) GetResult{
double result =0;
result = numberA+numberB;
return result;
}
@end
@interface OperationDiv :Operation
@end
@implementation OperationDiv
-(double)GetResult{
double result =0;
@try{
result = numberA/numberB;
}
@catch(NSException *exception) {
NSLog(@"除數(shù)不能為0");
}
return result;
}
@end
@interface OperationMul :Operation
@end
OperationMul類實(shí)現(xiàn)
#import "OperationMul.h"
@implementation OperationMul
-(double)GetResult{
double result =0;
result = numberA*numberB;
return result;
}
@end
@interface OperationSub :Operation
@end
@implementation OperationSub
-(double)GetResult{
double result =0;
result = numberA-numberB;
return result;
}
@end
#import "Operation.h"
@interface IFactory :NSObject
-(Operation*)CreateOperation;
@end
@implementation IFactory
-(Operation*)CreateOperation{
return [[Operation alloc]init];
}
@end
@interface AddFactory :IFactory
@end
@implementation AddFactory
-(Operation*)CreateOperation{
return [[OperationAdd alloc]init];
}
@end
@interface SubFactory :IFactory
@end
@implementation SubFactory
-(Operation*)CreateOperation{
return [[OperationSub alloc]init];
}
@end
@interface MulFactory :IFactory
@end
@implementation MulFactory
-(Operation*)CreateOperation{
return [[OperationMul alloc]init];
}
@end
@interfaceDiv Factory :IFactory
@end
@implementation DivFactory
-(Operation*)CreateOperation{
return [[OperationDiv alloc]init];
}
@end
int main (int argc,const char* argv[])
{
@autoreleasepool{
IFactory *operFactory = [[AddFactory alloc]init];
Operation *oper = [operFactory CreateOperation];
[oper setNumberA:1];
[oper setNumberB:2];
double result = [oper GetResult];
NSLog(@"The result is %f", result);
}
return 0;
}
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