7.01 - the simple factory.js

JS设计模式源代码

/* BicycleShop class. */

var BicycleShop = function() {};
BicycleShop.prototype = {
  sellBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    Interface.ensureImplements(bicycle, Bicycle);
    
    bicycle.assemble();
    bicycle.wash();
    
    return bicycle;
  }
};


/* The Bicycle interface. */

var Bicycle = new Interface('Bicycle', ['assemble', 'wash', 'ride', 'repair']);

/* Speedster class. */

var Speedster = function() { // implements Bicycle
  ...
};
Speedster.prototype = {
  assemble: function() {
    ...
  },
  wash: function() {
    ...
  },
  ride: function() {
    ...
  },
  repair: function() {
    ...
  }
};


/* Usage. */

var californiaCruisers = new BicycleShop();
var yourNewBike = californiaCruisers.sellBicycle('The Speedster');



/* BicycleFactory namespace. */

var BicycleFactory = {
  createBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    
    Interface.ensureImplements(bicycle, Bicycle);
    return bicycle;
  }
};

/* BicycleShop class, improved. */

var BicycleShop = function() {};
BicycleShop.prototype = {
  sellBicycle: function(model) {
    var bicycle = BicycleFactory.createBicycle(model);
    
    bicycle.assemble();
    bicycle.wash();
    
    return bicycle;
  }
};

/* BicycleFactory namespace, with more models. */

var BicycleFactory = {
  createBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Flatlander':
        bicycle = new Flatlander();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    
    Interface.ensureImplements(bicycle, Bicycle);
    return bicycle;
  }
};