设计模式-工厂模式

pattern-factory.js

// ===== 1.pattern-factory.js=====

// Car factory 
function Car (options) {
	this.type = options.type || 'car';
	this.owner = options.owner || null;
	this.price = options.price || null;
}

// Trunk factory
function Truck (options) {
	this.type = options.type || 'truck';
	this.owner = options.owner || null;
	this.price = options.price || null;
}

// Vehicle factory 
function Vehicle () {}

// set default prototype to Car
Vehicle.prototype.supClass = Car;

// create vehicle with options
Vehicle.prototype.create = function (options) {
	var type = options.type;
	if (type === 'car') {
		// create a car with Car factory
		this.supClass = Car;
	} else if (type === 'truck') {
		// create a truck with Trunk factory
		this.supClass = Truck;
	}

	// return a vehicle instance
	var vehicle = new this.supClass(options);
	return vehicle; 
}; 

// first we new a factory instance
var vehicleFactory = new Vehicle();

// now we create a car
var car = vehicleFactory.create({
	type: 'car',
	owner: 'xiaolai-1',
	price: 11111
});
console.log(car); 

// then we create a truck
var truck = vehicleFactory.create({
	type: 'truck',
	owner: 'xiaolai-2',
	price: 22222
});
console.log(truck); 


// ===== 2.pattern-abstract-factory.j =====

var AbstractFactory = (function () {
	// store registed vehicles
	var types = {};

	return {
		// register a new vehicle type
		register:  function (type, Vehicle) {
			// if types[type] exist
			if (types[type]) {
				// do nothing
			} else {
				// else register this new type
				types[type] = Vehicle;
			}

			return this;
		},
		// get vehicle from store and set custimal options generating an instance 
		get: function (type, custimalOptions) {
			var Vehicle = types[type];
			if (Vehicle) {
				return new Vehicle(custimalOptions);
			} else {
				// not exist
				return null;
			}
		}
	};
})();

// now we register two type of vehicles
AbstractFactory.register('car', Car);
AbstractFactory.register('truck', Truck);

// then we get instance with custimal options
var car = AbstractFactory.get('car', {
	'owner': 'xiaolai-3',
	'price': 33333
});
console.log(car);

var truck = AbstractFactory.get('truck', {
	'owner': 'xiaolai-4',
	'price': 44444
});
console.log(truck);

什么时候用工厂模式比较爽？

• 组件内部创建自身属性复杂度非常高时
• 需要动态地创建组件时
• 希望传递简要的参数，其他使用默认配置时