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Copy path3 - The role of the factory.js
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Copy path3 - The role of the factory.js
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100 lines (80 loc) · 3.02 KB
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/* Original AcmeBicycleShop factory class. */
// 原来的AcmBicycleShop类如下
var AcmeBicycleShop = function() {};
extend(AcmeBicycleShop, BicycleShop);
AcmeBicycleShop.prototype.createBicycle = function(model) {
var bicycle;
switch(model) {
case 'The Speedster':
bicycle = new AcmeSpeedster();
break;
case 'The Lowrider':
bicycle = new AcmeLowrider();
break;
case 'The Flatlander':
bicycle = new AcmeFlatlander();
break;
case 'The Comfort Cruiser':
default:
bicycle = new AcmeComfortCruiser();
}
Interface.ensureImplements(bicycle, Bicycle);
return bicycle;
};
/* AcmeBicycleShop factory class, with decorators. */
/**
* 这个类的改进版允许用户指定想为自行车配件的选件。
* 在这里使用工厂模式可以统揽各种类（既包括自行车类也包括装饰者类）
* 把所有这些信息保存在一个地方，用户就可以把实际的类名与客户代码隔离开，
* 这样以后添加新类或修改现有类也就更容易。
*/
var AcmeBicycleShop = function() {};
extend(AcmeBicycleShop, BicycleShop);
AcmeBicycleShop.prototype.createBicycle = function(model, options) {
// Instantiate the bicycle object.
var bicycle = new AcmeBicycleShop.models[model]();
// Iterate through the options and instantiate decorators.
for(var i = 0, len = options.length; i < len; i++) {
var decorator = AcmeBicycleShop.options[options[i].name];
if(typeof decorator !== 'function') {
throw new Error('Decorator ' + options[i].name + ' not found.');
}
var argument = options[i].arg;
bicycle = new decorator(bicycle, argument);
}
// Check the interface and return the finished object.
Interface.ensureImplements(bicycle, Bicycle);
return bicycle;
};
// Model name to class name mapping.
AcmeBicycleShop.models = {
'The Speedster': AcmeSpeedster,
'The Lowrider': AcmeLowrider,
'The Flatlander': AcmeFlatlander,
'The Comfort Cruiser': AcmeComfortCruiser
};
// Option name to decorator class name mapping.
AcmeBicycleShop.options = {
'headlight': HeadlightDecorator,
'taillight': TaillightDecorator,
'bell': BellDecorator,
'basket': BasketDecorator,
'color': FrameColorDecorator,
'lifetime warranty': LifetimeWarrantyDecorator,
'timed warranty': TimedWarrantyDecorator
};
// 创建装饰的自行车对象的两种不同做法
// 第一种做法不使用工厂，与客户代码紧密耦合在一起的类不下5个。
var myBicycle = new AcmeSpeedster();
myBicycle = new FrameColorDecorator(myBicycle, 'blue');
myBicycle = new HeadlightDecorator(myBicycle);
myBicycle = new TaillightDecorator(myBicycle);
myBicycle = new TimedWarrantyDecorator(myBicycle, 2);
// 第二种方法使用了工厂，与客户代码耦合在一起的只有一个类，即那个工厂本身。
var alecsCruisers = new AcmeBicycleShop();
var myBicycle = alecsCruisers.createBicycle('The Speedster', [
{ name: 'color', arg: 'blue' },
{ name: 'headlight' },
{ name: 'taillight' },
{ name: 'timed warranty', arg: 2 }
]);