Repository navigation
Expand file tree
/
Copy path1 - Car registration example.js
More file actions
116 lines (109 loc) · 3.47 KB
/
Copy path1 - Car registration example.js
File metadata and controls
116 lines (109 loc) · 3.47 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
/* Car class, un-optimized. */
// 示例：汽车登记
// 把每辆汽车表示为一个对象
var Car = function(make, model, year, owner, tag, renewDate) {
this.make = make;
this.model = model;
this.year = year;
this.owner = owner;
this.tag = tag;
this.renewDate = renewDate;
};
Car.prototype = {
getMake: function() {
return this.make;
},
getModel: function() {
return this.model;
},
getYear: function() {
return this.year;
},
transferOwnership: function(newOwner, newTag, newRenewDate) {
this.owner = newOwner;
this.tag = newTag;
this.renewDate = newRenewDate;
},
renewRegistration: function(newRenewDate) {
this.renewDate = newRenewDate;
},
isRegistrationCurrent: function() {
var today = new Date();
return today.getTime() < Date.parse(this.renewDate);
}
};
/* Car class, optimized as a flyweight. */
// 使用享元模式，把对象数据划分为内在状态和外在状态
var Car = function(make, model, year) {
this.make = make;
this.model = model;
this.year = year;
};
Car.prototype = {
getMake: function() {
return this.make;
},
getModel: function() {
return this.model;
},
getYear: function() {
return this.year;
}
};
// 上面代码删除了所有的外在数据。
// 所有处理登记事宜的方法都被转移到一个对象管理器中。
// 因为现在对象的数据已被分为两大部分，所以必须用工厂来实例化它。
/* CarFactory singleton. */
// 工厂说明：它会检查之前是否已经创建过对应于指定品牌-型号-出厂日期组合的汽车，如果存在这样的汽车那就返回它，
// 否则就创建一辆新车，并把它保存起来。这就确保了对应于每个唯一的内在状态。
var CarFactory = (function() {
var createdCars = {};
return {
createCar: function(make, model, year) {
// Check to see if this particular combination has been created before.
if(createdCars[make + '-' + model + '-' + year]) {
return createdCars[make + '-' + model + '-' + year];
}
// Otherwise create a new instance and save it.
else {
var car = new Car(make, model, year);
createdCars[make + '-' + model + '-' + year] = car;
return car;
}
}
};
})();
/* CarRecordManager singleton. */
// 封装在管理器中的外在状态
// 要完成这种优化还需要一个对象，用一个单例来做封装这些数据的管理器。
var CarRecordManager = (function() {
// 从Car类剥离的所有数据现在都保存在这个对象中
var carRecordDatabase = {};
return {
// Add a new car record into the city's system.
addCarRecord: function(make, model, year, owner, tag, renewDate) {
// 创建汽车
var car = CarFactory.createCar(make, model, year);
// 添加外在状态数据
carRecordDatabase[tag] = {
owner: owner,
renewDate: renewDate,
car: car
};
},
// Methods previously contained in the Car class.
transferOwnership: function(tag, newOwner, newTag, newRenewDate) {
var record = carRecordDatabase[tag];
record.owner = newOwner;
record.tag = newTag;
record.renewDate = newRenewDate;
},
renewRegistration: function(tag, newRenewDate) {
carRecordDatabase[tag].renewDate = newRenewDate;
},
isRegistrationCurrent: function(tag) {
var today = new Date();
return today.getTime() < Date.parse(carRecordDatabase[tag].renewDate);
}
};
})();