How to: Explicitly Implement Interface Members with Inheritance (C# Programming Guide)

显式接口实现还允许程序员实现具有相同成员名称的两个接口，并为每个接口成员各提供一个实现。本示例同时以公制单位和英制单位显示框的尺寸。Box 类实现 IEnglishDimensions 和 IMetricDimensions 两个接口，它们表示不同的度量系统。两个接口有相同的成员名称 Length 和 Width。

// Declare the English units interface:interface IEnglishDimensions{ float Length(); float Width();}// Declare the metric units interface:interface IMetricDimensions{ float Length(); float Width();}// Declare the Box class that implements the two interfaces:// IEnglishDimensions and IMetricDimensions:class Box : IEnglishDimensions, IMetricDimensions{ float lengthInches; float widthInches; public Box(float length, float width) { lengthInches = length; widthInches = width; } // Explicitly implement the members of IEnglishDimensions: float IEnglishDimensions.Length() { return lengthInches; } float IEnglishDimensions.Width() { return widthInches; } // Explicitly implement the members of IMetricDimensions: float IMetricDimensions.Length() { return lengthInches * 2.54f; } float IMetricDimensions.Width() { return widthInches * 2.54f; } static void Main() { // Declare a class instance box1: Box box1 = new Box(30.0f, 20.0f); // Declare an instance of the English units interface: IEnglishDimensions eDimensions = (IEnglishDimensions)box1; // Declare an instance of the metric units interface: IMetricDimensions mDimensions = (IMetricDimensions)box1; // Print dimensions in English units: System.Console.WriteLine("Length(in): {0}", eDimensions.Length()); System.Console.WriteLine("Width (in): {0}", eDimensions.Width()); // Print dimensions in metric units: System.Console.WriteLine("Length(cm): {0}", mDimensions.Length()); System.Console.WriteLine("Width (cm): {0}", mDimensions.Width()); }}/* Output: Length(in): 30 Width (in): 20 Length(cm): 76.2 Width (cm): 50.8*/

可靠编程

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如果希望默认度量采用英制单位，请正常实现 Length 和 Width 这两个方法，并从 IMetricDimensions 接口显式实现 Length 和 Width 方法：

// Normal implementation:public float Length(){ return lengthInches;}public float Width(){ return widthInches;}// Explicit implementation:float IMetricDimensions.Length(){ return lengthInches * 2.54f;}float IMetricDimensions.Width(){ return widthInches * 2.54f;}

这种情况下，可以从类实例访问英制单位，而从接口实例访问公制单位：

 public static void Test(){ Box box1 = new Box(30.0f, 20.0f); IMetricDimensions mDimensions = (IMetricDimensions)box1; System.Console.WriteLine("Length(in): {0}", box1.Length()); System.Console.WriteLine("Width (in): {0}", box1.Width()); System.Console.WriteLine("Length(cm): {0}", mDimensions.Length()); System.Console.WriteLine("Width (cm): {0}", mDimensions.Width());}