門面設計模式 - 實現

Question

我指的是可複用面向對象軟件上degign模式book元素由Eric Gamma值。然而，我理解了Facade模式的概念，但仍然無法理解本書給出的實現要點，因爲我對實現部分esp有點窮。

的下面是在書中提到的2點：

1. 減少客戶子系統耦合：通過使門面類的抽象類。

2. 公共V/S專用子系統類。

可能有人請解釋一下我這有一些例子或者用我的代碼有：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

namespace Facade_CSharp 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      Facade facade = new Facade(); 

      facade.ProcessA(); 
      facade.ProcessB(); 

      // Wait for user 
      Console.ReadKey(); 
     } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassA' class 
    /// </summary> 
    class SubSystemOne 
    { 
    public void MethodOne() 
    { 
     Console.WriteLine(" SubSystem One"); 
    } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassB' class 
    /// </summary> 
    class SubSystemTwo 
    { 
    public void MethodTwo() 
    { 
     Console.WriteLine(" SubSystem Two"); 
    } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassC' class 
    /// </summary> 
    class SubSystemThree 
    { 
    public void MethodThree() 
    { 
     Console.WriteLine(" SubSystem Three"); 
    } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassD' class 
    /// </summary> 
    class SubSystemFour 
    { 
    public void MethodFour() 
    { 
     Console.WriteLine(" SubSystem Four"); 
    } 
    } 

    /// <summary> 
    /// The 'Facade' class 
    /// </summary> 
    class Facade 
    { 
    private SubSystemOne _one; 
    private SubSystemTwo _two; 
    private SubSystemThree _three; 
    private SubSystemFour _four; 

    public Facade() 
    { 
     Console.WriteLine("\nRequests received from Client System and Facade is in execution... "); 

     _one = new SubSystemOne(); 
     _two = new SubSystemTwo(); 
     _three = new SubSystemThree(); 
     _four = new SubSystemFour(); 
    } 

    public void ProcessA() 
    { 
     Console.WriteLine("\nProcessA of Facade uses the following subsystems to accomplish the task:"); 
     _one.MethodOne(); 
     _two.MethodTwo(); 
     _four.MethodFour(); 
    } 

    public void ProcessB() 
    { 
     Console.WriteLine("\nProcessB of Facade uses the following subsystems to accomplish the task:"); 
     _two.MethodTwo(); 
     _three.MethodThree(); 
    } 
    } 
} 

代碼與抽象類：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

namespace Facade_abstract 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      FacadeAbs facade = new FacadeAbs(); 

      facade.ProcessA(); 
      facade.ProcessB(); 

      // Wait for user 
      Console.ReadKey(); 

     } 
    } 

    class SubSystemOne 
    { 
     public void MethodOne() 
     { 
      Console.WriteLine(" SubSystem One"); 
     } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassB' class 
    /// </summary> 
    class SubSystemTwo 
    { 
     public void MethodTwo() 
     { 
      Console.WriteLine(" SubSystem Two"); 
     } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassC' class 
    /// </summary> 
    class SubSystemThree 
    { 
     public void MethodThree() 
     { 
      Console.WriteLine(" SubSystem Three"); 
     } 
    } 

    /// <summary> 
    /// The 'Subsystem ClassD' class 
    /// </summary> 
    class SubSystemFour 
    { 
     public void MethodFour() 
     { 
      Console.WriteLine(" SubSystem Four"); 
     } 
    } 

    /// <summary> 
    /// The 'Facade' class 
    /// </summary> 
    public abstract class Facade 
    { 
     //public abstract Facade(); 

     public abstract void ProcessA(); 

     public abstract void ProcessB(); 

    } 

    public class FacadeAbs : Facade 
    { 
     private SubSystemOne _one; 
     private SubSystemTwo _two; 
     private SubSystemThree _three; 
     private SubSystemFour _four; 

     public FacadeAbs() 
     { 
      Console.WriteLine("\nRequests received from Client System and Facade is in execution... "); 

      _one = new SubSystemOne(); 
      _two = new SubSystemTwo(); 
      _three = new SubSystemThree(); 
      _four = new SubSystemFour(); 
     } 


     public override void ProcessA() 
     { 
      Console.WriteLine("\nProcessA of Facade uses the following subsystems to accomplish the task:"); 
      _one.MethodOne(); 
      _two.MethodTwo(); 
      _four.MethodFour(); 
     } 

     public override void ProcessB() 
     { 
      Console.WriteLine("\nProcessB of Facade uses the following subsystems to accomplish the task:"); 
      _two.MethodTwo(); 
      _three.MethodThree(); 
     } 

    } 
} 

Answer 1

門面用來減少程序之間的耦合。

如示例ProcessA調用3個方法 -
_one.MethodOne（）;
_two.MethodTwo（）;
_four.MethodFour（）;

而客戶端只是調用ProcessA方法。 立面僅用於減少耦合，依賴性。

如果沒有門面的客戶端將是一個調用這些方法。

所以門面類提供了以下 -

1. 隱藏多個呼叫。這有助於客戶必須進行一次通話。防止緊密耦合。例如僅適用於ProcessA
2. 如果任何方法更改添加或刪除參數，則客戶端代碼需要更改。然而，在外觀的情況下，更改不會影響客戶端。
3. 客戶端只有幾個公共訪問點到服務器端。服務器端可以封裝它的代碼。較少的失敗點。