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這篇文章主要介紹“如何利用C#實現(xiàn)接口事件”,在日常操作中,相信很多人在如何利用C#實現(xiàn)接口事件問題上存在疑惑,小編查閱了各式資料,整理出簡單好用的操作方法,希望對大家解答”如何利用C#實現(xiàn)接口事件”的疑惑有所幫助!接下來,請跟著小編一起來學習吧!
C#接口事件的實現(xiàn)是如何的呢?下面的C#接口事件示例演示如何在類中實現(xiàn)接口事件。實現(xiàn)C#接口事件的規(guī)則與實現(xiàn)任何接口方法或?qū)傩缘囊?guī)則基本相同。
C#接口事件實例:
在類中實現(xiàn)接口事件,在類中聲明事件,然后在適當?shù)膮^(qū)域調(diào)用該事件。
public interface IDrawingObject { event EventHandler ShapeChanged; } public class MyEventArgs : EventArgs {…} public class Shape : IDrawingObject { event EventHandler ShapeChanged; void ChangeShape() { // Do something before the event… OnShapeChanged(new MyEventsArgs(…)); // or do something after the event. } protected virtual void OnShapeChanged(MyEventArgs e) { if(ShapeChanged != null) { ShapeChanged(this, e); } } }
C#接口事件示例
下面的示例演示如何處理以下的不常見情況:您的類是從兩個以上的接口繼承的,每個接口都含有同名事件)。在這種情況下,您至少要為其中一個事件提供顯式接口實現(xiàn)。為事件編寫顯式接口實現(xiàn)時,必須編寫 add 和 remove 事件訪問器。這兩個事件訪問器通常由編譯器提供,但在這種情況下編譯器不能提供。
您可以提供自己的訪問器,以便指定這兩個事件是由您的類中的同一事件表示,還是由不同事件表示。例如,根據(jù)接口規(guī)范,如果事件應(yīng)在不同時間引發(fā),則可以將每個事件與類中的一個單獨實現(xiàn)關(guān)聯(lián)。在下面的示例中,訂戶將形狀引用強制轉(zhuǎn)換為 IShape 或 IDrawingObject,從而確定自己將會接收哪個 OnDraw 事件。
C#接口事件代碼:
namespace WrapTwoInterfaceEvents { using System; public interface IDrawingObject { // Raise this event before drawing // the object. event EventHandler OnDraw; } public interface IShape { // Raise this event after drawing // the shape. event EventHandler OnDraw; } // Base class event publisher inherits two // interfaces, each with an OnDraw event public class Shape : IDrawingObject, IShape { // Create an event for each interface event event EventHandler PreDrawEvent; event EventHandler PostDrawEvent; object objectLock = new Object(); // Explicit interface implementation required. // Associate IDrawingObject's event with // PreDrawEvent event EventHandler IDrawingObject.OnDraw { add { lock (objectLock) { PreDrawEvent += value; } } remove { lock (objectLock) { PreDrawEvent -= value; } } } // Explicit interface implementation required. // Associate IShape's event with // PostDrawEvent event EventHandler IShape.OnDraw { add { lock (objectLock) { PostDrawEvent += value; } } remove { lock (objectLock) { PostDrawEvent -= value; } } } // For the sake of simplicity this one method // implements both interfaces. public void Draw() { // Raise IDrawingObject's event before the object is drawn. EventHandler handler = PreDrawEvent; if (handler != null) { handler(this, new EventArgs()); } Console.WriteLine("Drawing a shape."); // RaiseIShape's event after the object is drawn. handler = PostDrawEvent; if (handler != null) { handler(this, new EventArgs()); } } } public class Subscriber1 { // References the shape object as an IDrawingObject public Subscriber1(Shape shape) { IDrawingObject d = (IDrawingObject)shape; d.OnDraw += new EventHandler(d_OnDraw); } void d_OnDraw(object sender, EventArgs e) { Console.WriteLine("Sub1 receives the IDrawingObject event."); } } // References the shape object as an IShape public class Subscriber2 { public Subscriber2(Shape shape) { IShape d = (IShape)shape; d.OnDraw += new EventHandler(d_OnDraw); } void d_OnDraw(object sender, EventArgs e) { Console.WriteLine("Sub2 receives the IShape event."); } } public class Program { static void Main(string[] args) { Shape shape = new Shape(); Subscriber1 sub = new Subscriber1(shape); Subscriber2 sub2 = new Subscriber2(shape); shape.Draw(); // Keep the console window open in debug mode. System.Console.WriteLine("Press any key to exit."); System.Console.ReadKey(); } } }
/* C#接口事件示例Output: Sub1 receives the IDrawingObject event. Drawing a shape. Sub2 receives the IShape event. */
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