觀察者模式、MVP、MVC、三層架構
2010-01-11 08:57 【當耐特】 閱讀(7246) 評論(12) 收藏 舉報.NET內置觀察者模式
MVC的由來？
三層架構的由來？
秉著重構的思想，一步一步從觀察者模式重構到MVC重構到三層架構！
【一】.NET內置的觀察者模式--事件
1 public class MyEventArgs : EventArgs
2 {
3 private int id;
4 public int Id
5 {
6 get{return this.id;}
7 }
8 public MyEventArgs(int id)
9 {
10 this.id = id;
11 }
12 }
13
14 public class User
15 {
16 public event EventHandler<MyEventArgs> IdChanged;
17 private int id;
18 public int Id
19 {
20 get { return id; }
21 set
22 {
23 id = value;
24 IdChanged(this, new MyEventArgs(id));
25 }
26 }
27 }
28
29
30 public class Controller
31 {
32 User user = new User();
33 private void OnIdChanged(object send, MyEventArgs args)
34 {
35 //把改變后的Id顯示在網頁里面
36 ShowInInerteNet(user);
37 }
38 public void Test()
39 {
40 user.IdChanged += this.OnIdChanged;
41 //改變Id
42 user.Id="1314";
43 }
44 }
2 {
3 private int id;
4 public int Id
5 {
6 get{return this.id;}
7 }
8 public MyEventArgs(int id)
9 {
10 this.id = id;
11 }
12 }
13
14 public class User
15 {
16 public event EventHandler<MyEventArgs> IdChanged;
17 private int id;
18 public int Id
19 {
20 get { return id; }
21 set
22 {
23 id = value;
24 IdChanged(this, new MyEventArgs(id));
25 }
26 }
27 }
28
29
30 public class Controller
31 {
32 User user = new User();
33 private void OnIdChanged(object send, MyEventArgs args)
34 {
35 //把改變后的Id顯示在網頁里面
36 ShowInInerteNet(user);
37 }
38 public void Test()
39 {
40 user.IdChanged += this.OnIdChanged;
41 //改變Id
42 user.Id="1314";
43 }
44 }
這就是觀察者模式，就這么簡單。
【二】MVC的由來
如果我不想讓id顯示在網頁里，我要讓他顯示在winform窗體里,那么類Controller的程序要頻繁滴改動，根據開放關閉原則----對擴展開發 對修改關閉，所以很容易讓人想到抽象出顯示方式的。所以有：
1 public interface IView
2 {
3 public void Show(User user);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(User user)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(User user)
15 {
16 //doSomething
17 }
18 }
19 public class Controller
20 {
21 //這里可以實現依賴注入
22 private CustomShow customShow=new IntertNetShow();
23 User user = new User();
24 private void OnIdChanged(object send, MyEventArgs args)
25 {
26 customShow.Show(user);
27 }
28 public void Test()
29 {
30 user.IdChanged += this.OnIdChanged;
31 //改變Id
32 GetIdFormDB(user);
33 }
34 }
2 {
3 public void Show(User user);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(User user)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(User user)
15 {
16 //doSomething
17 }
18 }
19 public class Controller
20 {
21 //這里可以實現依賴注入
22 private CustomShow customShow=new IntertNetShow();
23 User user = new User();
24 private void OnIdChanged(object send, MyEventArgs args)
25 {
26 customShow.Show(user);
27 }
28 public void Test()
29 {
30 user.IdChanged += this.OnIdChanged;
31 //改變Id
32 GetIdFormDB(user);
33 }
34 }
上面是user.Id是直接賦值，現在我想從數據庫中讀出id的值或者從XML中讀出user.Id的值，那么Control類就需要頻繁的修改。根據開發關閉原則-----對擴展開發 對修改關閉，也和上面同樣的思想,把改變Id的方法抽象出來。
1 public interface IModel
2 {
3 public void GetId(User user);
4 }
5 public class GetIdFromDB: IModel
6 {
7 public void GetId(User user)
8 {
9 //doSomething
10 }
11 }
12 public class GetIdFromXML:IModel
13 {
14 public void GetId(User user)
15 {
16 //doSomething
17 }
18 }
19 public class Control
20 {
21 //這里可以實現依賴注入
22 private IView view=new IntertNetShow();
23 //這里可以實現依賴注入
24 private IModel model=new GetIdFromDB();
25 User user = new User();
26 private void OnIdChanged(object send, MyEventArgs args)
27 {
28 view.Show(user);
29 }
30 public void Test()
31 {
32 user.IdChanged += this.OnIdChanged;
33 //改變Id
34 model.GetId(user);
35 }
36 }
2 {
3 public void GetId(User user);
4 }
5 public class GetIdFromDB: IModel
6 {
7 public void GetId(User user)
8 {
9 //doSomething
10 }
11 }
12 public class GetIdFromXML:IModel
13 {
14 public void GetId(User user)
15 {
16 //doSomething
17 }
18 }
19 public class Control
20 {
21 //這里可以實現依賴注入
22 private IView view=new IntertNetShow();
23 //這里可以實現依賴注入
24 private IModel model=new GetIdFromDB();
25 User user = new User();
26 private void OnIdChanged(object send, MyEventArgs args)
27 {
28 view.Show(user);
29 }
30 public void Test()
31 {
32 user.IdChanged += this.OnIdChanged;
33 //改變Id
34 model.GetId(user);
35 }
36 }
所以重構完成===》MVP. 完整的代碼如下：
代碼
1 public interface IView
2 {
3 public void Show(User user);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(User user)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(User user)
15 {
16 //doSomething
17 }
18 }
19
20 public interface IModel
21 {
22 public void GetId(User user);
23 }
24 public class GetIdFromDB: IModel
25 {
26 public void GetId(User user)
27 {
28 //doSomething
29 }
30 }
31 public class GetIdFromXML:IModel
32 {
33 public void GetId(User user)
34 {
35 //doSomething
36 }
37 }
38
39 public class Controller
40 {
41 //這里可以實現依賴注入
42 private IView view=new IntertNetShow();
43 //這里可以實現依賴注入
44 private IModel model=new GetIdFromDB();
45 User user = new User();
46 private void OnIdChanged(object send, MyEventArgs args)
47 {
48 view.Show(user);
49 }
50 public void Test()
51 {
52 user.IdChanged += this.OnIdChanged;
53 //改變Id
54 model.GetId(user);
55 }
56 }
2 {
3 public void Show(User user);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(User user)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(User user)
15 {
16 //doSomething
17 }
18 }
19
20 public interface IModel
21 {
22 public void GetId(User user);
23 }
24 public class GetIdFromDB: IModel
25 {
26 public void GetId(User user)
27 {
28 //doSomething
29 }
30 }
31 public class GetIdFromXML:IModel
32 {
33 public void GetId(User user)
34 {
35 //doSomething
36 }
37 }
38
39 public class Controller
40 {
41 //這里可以實現依賴注入
42 private IView view=new IntertNetShow();
43 //這里可以實現依賴注入
44 private IModel model=new GetIdFromDB();
45 User user = new User();
46 private void OnIdChanged(object send, MyEventArgs args)
47 {
48 view.Show(user);
49 }
50 public void Test()
51 {
52 user.IdChanged += this.OnIdChanged;
53 //改變Id
54 model.GetId(user);
55 }
56 }
重構至MVC,完整代碼如下
代碼
1 public interface IView
2 {
3 public void Show(IModel model);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(IModel model)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(IModel model)
15 {
16 //doSomething
17 }
18 }
19
20 public interface IModel
21 {
22 public User GetId(User user);
23 }
24 public class GetIdFromDB: IModel
25 {
26 public User GetId(User user)
27 {
28 //doSomething
29 }
30 }
31 public class GetIdFromXML:IModel
32 {
33 public User GetId(User user)
34 {
35 //doSomething
36 }
37 }
38
39 public class Controller
40 {
41 //這里可以實現依賴注入
42 private IView view=new IntertNetShow();
43 //這里可以實現依賴注入
44 private IModel model=new GetIdFromDB();
45 User user = new User();
46 private void OnIdChanged(object send, MyEventArgs args)
47 {
48 view.Show(model);
49 }
50 public void Test()
51 {
52 user.IdChanged += this.OnIdChanged;
53 //改變Id
54 model.GetId(user);
55 }
56 }
2 {
3 public void Show(IModel model);
4 }
5 public class IntertNetShow:IView
6 {
7 public void Show(IModel model)
8 {
9 //doSomething
10 }
11 }
12 public class WinFormShow:IView
13 {
14 public void Show(IModel model)
15 {
16 //doSomething
17 }
18 }
19
20 public interface IModel
21 {
22 public User GetId(User user);
23 }
24 public class GetIdFromDB: IModel
25 {
26 public User GetId(User user)
27 {
28 //doSomething
29 }
30 }
31 public class GetIdFromXML:IModel
32 {
33 public User GetId(User user)
34 {
35 //doSomething
36 }
37 }
38
39 public class Controller
40 {
41 //這里可以實現依賴注入
42 private IView view=new IntertNetShow();
43 //這里可以實現依賴注入
44 private IModel model=new GetIdFromDB();
45 User user = new User();
46 private void OnIdChanged(object send, MyEventArgs args)
47 {
48 view.Show(model);
49 }
50 public void Test()
51 {
52 user.IdChanged += this.OnIdChanged;
53 //改變Id
54 model.GetId(user);
55 }
56 }
可以看得出MVC比MVP更加松耦合！
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