Robotlegs2 學習筆記 -- SwiftSuspenders 2.x （1）

Swiftsuspenders2 是一個基於元數據(metadata)的IOC(控制反轉，inversion of control)的AS3的解決方案。反轉控制又被稱依賴注射（Dependency Injection），也就是將依賴先剝離，而後在適當時候再注射進入。它是一種下降耦合度的程序設計模式其核心原則是高層模塊不該依賴於低層模塊，他們都應該依賴於抽象。抽象不依賴細節，細節依賴抽象，它經過將對象的建立過程解耦出來來下降對象間的依賴關係。IOC的設計目標是不直接建立對象，可是描述對象的建立方式，在代碼中不直接連接對象和服務，經過配置的方式描述哪種組件須要哪一些服務，而後在ioc容器中負責自動將對象服務和須要使用他們的地方進行連接。下面咱們經過一個簡單的例子，先了解一下如何利用依賴注入進行解耦。

關於依賴注入

當咱們須要進行一個發送消息或者郵件的流程時 咱們可能會寫以下代碼（demo0）：

 1 package  demo0
 2 {
 3     /**
 4      * ...
 5      * @author titi
 6      */
 7     public class Mail 
 8     {
 9         public var Title:String;
10         
11         public function Send():void
12         {
13             trace(" Send Mail:"+Title);
14         }
15         
16         public function Mail(title:String) 
17         {
18             Title = title;
19         }
20         
21     }
22 
23 　　}
24 　　
25 　　
26 package  demo0
27 {
28     /**
29      * ...
30      * @author titi
31      */
32     public class Notification 
33     {
34         private var _email:Mail;
35         public function Notification() 
36         {
37             _email = new Mail("測試郵件1");
38         }
39         
40         
41         public function PromotionalNotification():void
42         {
43             _email.Send();
44         }
45     }
46 
47 　　}
48 　　
49 　　
50 package demo0
51 {
52     import flash.display.Sprite;
53     import flash.events.Event;
54     
55     /**
56      * ...
57      * @author titi
58      */
59     public class Main0 extends Sprite 
60     {
61         
62         public function Main0():void 
63         {
64             if (stage) init();
65             else addEventListener(Event.ADDED_TO_STAGE, init);
66         }
67         
68         private function init(e:Event = null):void 
69         {
70             removeEventListener(Event.ADDED_TO_STAGE, init);
71             // entry point
72             var notificatoin:Notification = new Notification();
73             notificatoin.PromotionalNotification();
74         }
75         
76     }
77     
78 　　}

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這裏Mail和其控制器Notification 是直接關聯的，控制器依賴Mail對象。經過抽象Mail 能夠進行解耦下降Notification和Mail的耦合度。

 1 package demo1 
 2 {
 3     
 4     /**
 5      * ...
 6      * @author titi
 7      */
 8     public interface IMsg 
 9     {
10         function set Title(value:String):void;
11         
12         function get Title():String;
13         
14         function Send():void;
15     }
16     
17 }
18 　　
19 package  demo1
20 {
21     /**
22      * ...
23      * @author titi
24      */
25     public class Mail implements  IMsg
26     {
27         public var _Title:String;
28         
29         public function Send():void
30         {
31             trace(" Send Mail:"+Title);
32         }
33         
34         public function Mail(title:String) 
35         {
36             _Title = title;
37         }
38         
39         /* INTERFACE demo1.IMsg */
40         
41         public function set Title(value:String):void 
42         {
43             _Title = value;
44         }
45         
46         public function get Title():String 
47         {
48             return _Title;
49         }
50         
51     }
52 
53 }
54 
55  package  demo1
56 {
57     /**
58      * ...
59      * @author titi
60      */
61     public class Notification 
62     {
63         private var _email:IMsg;
64 
65         public function PromotionalNotification():void
66         {
67             _email.Send();
68         }
69     }
70 
71 }

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抽象後 能夠經過四種方式(注入點) 在Notification 中注入IMail對應的具體的Mail 分別是

 

一、構造函數注入

 1 package  demo1
 2 {
 3     /**
 4      * ...
 5      * @author titi
 6      */
 7     public class Notification 
 8     {
 9         private var _email:IMsg;
10         public function Notification(email:IMsg) 
11         {
12             _email = email;
13         }
14         
15         
16         public function PromotionalNotification():void
17         {
18             _email.Send();
19         }
20     }
21 
22 }

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二、方法注入

 1 package  demo1
 2 {
 3     /**
 4      * ...
 5      * @author titi
 6      */
 7     public class Notification3
 8     {
 9         private var _email:IMsg;
10         
11         public function Notification3() 
12         {
13             
14         }
15         
16         
17         public function PromotionalNotification(mail:IMsg):void
18         {
19             mail.Send();
20         }
21     }
22 
23 }

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三、屬性注入

 1 package  demo1
 2 {
 3     /**
 4      * ...
 5      * @author titi
 6      */
 7     public class Notification2
 8     {
 9         private var _email:IMsg;
10         
11         public function Notification2() 
12         {
13             
14         }
15         
16         
17         public function PromotionalNotification():void
18         {
19             _email.Send();
20         }
21 
22         //提供供外部注入Set屬性
23         public function set email(value:IMsg):void 
24         {
25             _email = value;
26         }
27     }
28 
29 }

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四、變量注入

 1 package  demo1
 2 {
 3     /**
 4      * ...
 5      * @author titi
 6      */
 7     public class Notification4
 8     {
 9         /**
10          * 公共變量提供抽象注入
11          */
12         public var _email:IMsg;
13         
14         public function Notification4() 
15         {
16             
17         }
18         
19         
20         public function PromotionalNotification():void
21         {
22             _email.Send();
23         }
24 
25     }
26 
27 }

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在Demo1中咱們用以下代碼來進行顯示的抽象注入:

 1 package demo1
 2 {
 3     import flash.display.Sprite;
 4     import flash.events.Event;
 5     
 6     /**
 7      * ...
 8      * @author titi
 9      */
10     public class Main1 extends Sprite 
11     {
12         
13         public function Main1():void 
14         {
15             if (stage) init();
16             else addEventListener(Event.ADDED_TO_STAGE, init);
17         }
18         
19         private function init(e:Event = null):void 
20         {
21             removeEventListener(Event.ADDED_TO_STAGE, init);
22             // entry point
23             
24             //構造依賴
25             var notificatoin:Notification = new Notification(new Mail("測試郵件1"));
26             notificatoin.PromotionalNotification();
27             //屬性依賴
28             var notificatoin2:Notification2 = new Notification2();
29             notificatoin2.email = new Mail("測試郵件2");
30             notificatoin2.PromotionalNotification();
31             //方法依賴
32             var notificatoin3:Notification3 = new Notification3();
33             notificatoin3.PromotionalNotification(new Mail("測試郵件3"));
34             //變量依賴
35             var notificatoin4:Notification4 = new Notification4();
36             notificatoin4._email=new Mail("測試郵件4")
37             notificatoin4.PromotionalNotification();
38         }
39         
40     }
41     
42 }

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執行後輸出以下:

1  Send Mail:測試郵件1
2  Send Mail:測試郵件2
3  Send Mail:測試郵件3
4  Send Mail:測試郵件4

上面2個demo大體說明了如何經過依賴注入對現有的邏輯進行解耦，接下來咱們用Swiftsuspenders2框架來快速實現上述的demo1做爲對Swiftsuspenders2框架的入門詳細參考以下demo2代碼。

 

  1 package  demo2
  2 {
  3     /**
  4      * ...
  5      * @author titi
  6      */
  7     
  8     [Inject(name="email1")]
  9     public class Notification 
 10     {
 11         private var _email:IMsg;
 12         public function Notification(email:IMsg) 
 13         {
 14             _email = email;
 15         }
 16         
 17         
 18         public function PromotionalNotification():void
 19         {
 20             _email.Send();
 21         }
 22     }
 23 
 24 }
 25 
 26 package  demo2
 27 {
 28     /**
 29      * ...
 30      * @author titi
 31      */
 32     public class Notification2
 33     {
 34         private var _email:IMsg;
 35         
 36         public function Notification2() 
 37         {
 38             
 39         }
 40         
 41         
 42         public function PromotionalNotification():void
 43         {
 44             _email.Send();
 45         }
 46         
 47         public function get email():IMsg 
 48         {
 49             return _email;
 50         }
 51         
 52         [Inject(name="email2")]
 53         public function set email(value:IMsg):void 
 54         {
 55             _email = value;
 56         }
 57     }
 58 
 59 }
 60 package  demo2
 61 {
 62     /**
 63      * ...
 64      * @author titi
 65      */
 66     public class Notification3
 67     {
 68         private var _email:IMsg;
 69         
 70         public function Notification3() 
 71         {
 72             
 73         }
 74         
 75         [Inject(name = "email3")]
 76         public function inject(mail:IMsg):void
 77         {
 78             _email = mail;
 79         }
 80         
 81         public function PromotionalNotification():void
 82         {
 83             _email.Send();
 84         }
 85     }
 86 
 87 }
 88 
 89 package  demo2
 90 {
 91     /**
 92      * ...
 93      * @author titi
 94      */
 95     public class Notification4
 96     {
 97         /**
 98          * 公共變量提供抽象注入
 99          */
100         
101         [Inject(name = "email4")]
102         public var _email:IMsg;
103         
104         public function Notification4() 
105         {
106             
107         }
108         
109         
110         public function PromotionalNotification():void
111         {
112             _email.Send();
113         }
114 
115     }
116 
117 }
118 
119 package demo2
120 {
121     import flash.display.Sprite;
122     import flash.events.Event;
123     import org.swiftsuspenders.Injector;
124     
125     /**
126      * ...
127      * @author titi
128      */
129     public class Main2 extends Sprite 
130     {
131         
132         public function Main2():void 
133         {
134             if (stage) init();
135             else addEventListener(Event.ADDED_TO_STAGE, init);
136         }
137         
138         private function init(e:Event = null):void 
139         {
140             removeEventListener(Event.ADDED_TO_STAGE, init);
141             // entry point
142             
143             //申明注入器
144             var injector:Injector = new Injector();
145             
146             injector.map(IMsg, "email1").toValue(new Mail("測試郵件1"));
147             injector.map(IMsg, "email2").toValue(new Mail("測試郵件2"));
148             injector.map(IMsg, "email3").toValue(new Mail("測試郵件3"));
149             injector.map(IMsg, "email4").toValue(new Mail("測試郵件4"));
150             
151             (injector.instantiateUnmapped(Notification) as Notification).PromotionalNotification();
152             (injector.instantiateUnmapped(Notification2) as Notification2).PromotionalNotification();
153             (injector.instantiateUnmapped(Notification3) as Notification3).PromotionalNotification();
154             (injector.instantiateUnmapped(Notification4) as Notification4).PromotionalNotification();
155         }
156         
157     }
158     
159 }

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