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C#利用反射ConstructorInfo类动态创建类

    本文由【shakusi 原创】

    最近刚换工作，其中项目中用到一个动态创建类的问题，后来研究了微软的ConstructorInfo类解决此问题。其中作了多次尝试，才正确理解此类的用法。

    现在作一个例子以便容易理解。

    假定一个买苹果的程序是这样：苹果分为红苹果和青苹果，它们在上半年和下半年单价不一样；它们不同产地的价格在不同时间也不一样。输入苹果名称，显示单价，再输入产地，显示此苹果此产地单价。

    步骤：

    1、在VS2008上新建一个控制台应用程序，名称为InvokeApple

    2、新建类Apple.cs（苹果父类）

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  5. using System.Reflection;  
  7. namespace InvokeApple  
  8. {  
  9. /// <summary>
  10. /// 基类
  11. /// </summary>
  12. public class Apple  
  13.     {  
  14. public string _strName;  
  16. public double _dPrice;  
  18. public string strName  
  19.         {  
  20. get
  21.             {  
  22. return this._strName;  
  23.             }  
  24. set
  25.             {  
  26.                 _strName = value;  
  27.             }  
  28.         }  
  30. public double dPrice  
  31.         {  
  32. get
  33.             {  
  34. return this._dPrice;  
  35.             }  
  36. set
  37.             {  
  38.                 _dPrice = value;  
  39.             }  
  40.         }  
  42. /// <summary>
  43. /// 通过输入苹果的名称生成所需的苹果类
  44. /// </summary>
  45. /// <param name="childType"></param>
  46. /// <param name="iba"></param>
  47. /// <returns></returns>
  48. public static Apple CreateApple(Type childType, IBuyApple iba)  
  49.         {  
  50.             ConstructorInfo ci = childType.GetConstructor(new Type[] { typeof(IBuyApple) });  
  51.             Apple apple = (Apple)ci.Invoke(new object[] { iba });  
  52. return  apple;  
  53.         }  
  55. /// <summary>
  56. /// 通过输入苹果的名称和产地生成所需的苹果类
  57. /// </summary>
  58. /// <param name="childType"></param>
  59. /// <param name="iba"></param>
  60. /// <param name="strOrigin"></param>
  61. /// <returns></returns>
  62. public static Apple CreateApple(Type childType, IBuyApple iba, string strOrigin)  
  63.         {  
  64.             ConstructorInfo ci = childType.GetConstructor(new Type[] { typeof(IBuyApple), typeof(string) });  
  65.             Apple apple = (Apple)ci.Invoke(new object[] { iba, strOrigin });  
  66. return apple;  
  67.         }  
  68.     }  
  69. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Reflection; namespace InvokeApple { /// <summary> /// 基类 /// </summary> public class Apple { public string _strName; public double _dPrice; public string strName { get { return this._strName; } set { _strName = value; } } public double dPrice { get { return this._dPrice; } set { _dPrice = value; } } /// <summary> /// 通过输入苹果的名称生成所需的苹果类 /// </summary> /// <param name="childType"></param> /// <param name="iba"></param> /// <returns></returns> public static Apple CreateApple(Type childType, IBuyApple iba) { ConstructorInfo ci = childType.GetConstructor(new Type[] { typeof(IBuyApple) }); Apple apple = (Apple)ci.Invoke(new object[] { iba }); return apple; } /// <summary> /// 通过输入苹果的名称和产地生成所需的苹果类 /// </summary> /// <param name="childType"></param> /// <param name="iba"></param> /// <param name="strOrigin"></param> /// <returns></returns> public static Apple CreateApple(Type childType, IBuyApple iba, string strOrigin) { ConstructorInfo ci = childType.GetConstructor(new Type[] { typeof(IBuyApple), typeof(string) }); Apple apple = (Apple)ci.Invoke(new object[] { iba, strOrigin }); return apple; } } }

[csharp] view plaincopyprint?

  1. </pre><pre name="code" class="csharp">    3、新建类RedApple.cs（红苹果） 

</pre><pre name="code" class="csharp">    3、新建类RedApple.cs（红苹果）

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  6. namespace InvokeApple  
  7. {  
  8. /// <summary>
  9. /// 红苹果
  10. /// </summary>
  11. public class RedApple : Apple  
  12.     {  
  13. public RedApple(IBuyApple iba)  
  14.         {  
  15. int i = iba.GetMonth();  
  16.             strName = "红苹果";  
  17. if (i >= 7)  
  18.             {  
  19.                 dPrice = 8.5;  
  20.             }  
  21. else
  22.             {  
  23.                 dPrice = 13.5;  
  24.             }  
  25.         }  
  27. /// <summary>
  28. /// 
  29. /// </summary>
  30. /// <param name="iba"></param>
  31. /// <param name="strOrigin">产地</param>
  32. public RedApple(IBuyApple iba, string strOrigin)  
  33.         {  
  34. int i = iba.GetMonth();  
  35.             strName = "红苹果";  
  36. if (i >= 7)  
  37.             {  
  38. if (strOrigin == "山东")  
  39.                 {  
  40.                     dPrice = 9.5;  
  41.                 }  
  42. else
  43. if (strOrigin == "山南")  
  44.                     {  
  45.                         dPrice = 11.5;  
  46.                     }  
  47. else
  48.                     {  
  49.                         dPrice = 10.5;  
  50.                     }  
  51.             }  
  52. else
  53.             {  
  54. if (strOrigin == "山东")  
  55.                 {  
  56.                     dPrice = 14.5;  
  57.                 }  
  58. else
  59. if (strOrigin == "山南")  
  60.                     {  
  61.                         dPrice = 17.5;  
  62.                     }  
  63. else
  64.                     {  
  65.                         dPrice = 15.5;  
  66.                     }  
  67.             }  
  68.         }  
  69.     }  
  70. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InvokeApple { /// <summary> /// 红苹果 /// </summary> public class RedApple : Apple { public RedApple(IBuyApple iba) { int i = iba.GetMonth(); strName = "红苹果"; if (i >= 7) { dPrice = 8.5; } else { dPrice = 13.5; } } /// <summary> /// /// </summary> /// <param name="iba"></param> /// <param name="strOrigin">产地</param> public RedApple(IBuyApple iba, string strOrigin) { int i = iba.GetMonth(); strName = "红苹果"; if (i >= 7) { if (strOrigin == "山东") { dPrice = 9.5; } else if (strOrigin == "山南") { dPrice = 11.5; } else { dPrice = 10.5; } } else { if (strOrigin == "山东") { dPrice = 14.5; } else if (strOrigin == "山南") { dPrice = 17.5; } else { dPrice = 15.5; } } } } }     4、新建类GreenApple.cs（青苹果子类）

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  6. namespace InvokeApple  
  7. {   
  8. /// <summary>
  9. /// 青苹果
  10. /// </summary>
  11. public class GreenApple : Apple  
  12.     {   
  13. public GreenApple(IBuyApple iba)  
  14.         {  
  15. int i = iba.GetMonth();  
  16.             strName = "青苹果";  
  17. if (i >= 7)  
  18.             {  
  19.                 dPrice = 4.5;  
  20.             }  
  21. else
  22.             {  
  23.                 dPrice = 5.5;  
  24.             }  
  25.         }  
  27. /// <summary>
  28. /// 
  29. /// </summary>
  30. /// <param name="iba"></param>
  31. /// <param name="strOrigin">产地</param>
  32. public GreenApple(IBuyApple iba, string strOrigin)  
  33.         {  
  34. int i = iba.GetMonth();  
  35.             strName = "青苹果";  
  36. if (i >= 7)  
  37.             {  
  38. if (strOrigin == "山东")  
  39.                 {  
  40.                     dPrice = 3.5;  
  41.                 }  
  42. else
  43. if (strOrigin == "山南")  
  44.                     {  
  45.                         dPrice = 6.25;  
  46.                     }  
  47. else
  48.                     {  
  49.                         dPrice = 4.7;  
  50.                     }  
  51.             }  
  52. else
  53.             {  
  54. if (strOrigin == "山东")  
  55.                 {  
  56.                     dPrice = 6.3;  
  57.                 }  
  58. else
  59. if (strOrigin == "山南")  
  60.                     {  
  61.                         dPrice = 7.2;  
  62.                     }  
  63. else
  64.                     {  
  65.                         dPrice = 6.5;  
  66.                     }  
  67.             }  
  68.         }  
  69.     }  
  70. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InvokeApple { /// <summary> /// 青苹果 /// </summary> public class GreenApple : Apple { public GreenApple(IBuyApple iba) { int i = iba.GetMonth(); strName = "青苹果"; if (i >= 7) { dPrice = 4.5; } else { dPrice = 5.5; } } /// <summary> /// /// </summary> /// <param name="iba"></param> /// <param name="strOrigin">产地</param> public GreenApple(IBuyApple iba, string strOrigin) { int i = iba.GetMonth(); strName = "青苹果"; if (i >= 7) { if (strOrigin == "山东") { dPrice = 3.5; } else if (strOrigin == "山南") { dPrice = 6.25; } else { dPrice = 4.7; } } else { if (strOrigin == "山东") { dPrice = 6.3; } else if (strOrigin == "山南") { dPrice = 7.2; } else { dPrice = 6.5; } } } } }     5、新建一个接口IBuyApple.cs（计算当前月份）

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  6. namespace InvokeApple  
  7. {  
  8. public interface IBuyApple  
  9.     {  
  10. /// <summary>
  11. /// 获取当前月份
  12. /// </summary>
  13. /// <returns></returns>
  14. int GetMonth();  
  15.     }  
  16. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InvokeApple { public interface IBuyApple { /// <summary> /// 获取当前月份 /// </summary> /// <returns></returns> int GetMonth(); } }
    6、新建买苹果方法类BuyApple.cs（计算当前月份）

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  6. namespace InvokeApple  
  7. {  
  8. public class BuyApple : IBuyApple  
  9.     {  
  10. public int GetMonth()  
  11.         {  
  12. return DateTime.Now.Month;  
  13.         }  
  14.     }  
  15. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InvokeApple { public class BuyApple : IBuyApple { public int GetMonth() { return DateTime.Now.Month; } } }
    7、主程序Program.cs

[csharp] view plaincopyprint?

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  6. namespace InvokeApple  
  7. {  
  8. class Program  
  9.     {  
  10. static void Main(string[] args)  
  11.         {  
  12.             Console.WriteLine("您要买什么苹果？");  
  13.             Console.WriteLine("请输入:");  
  14. string s = Console.ReadLine();  
  16. //需要创建的类
  17.             Type t1;  
  18. string strp = "";  
  19. if (s.Equals("红苹果"))  
  20.             {  
  21.                 t1 = typeof(RedApple);  
  22.             }  
  23. else
  24.             {  
  25.                 t1 = typeof(GreenApple);  
  26.             }  
  28.             BuyApple ba = new BuyApple();  
  29. //产生所需类
  30.             Apple ap = Apple.CreateApple(t1, ba);  
  32. if (s.Equals("红苹果"))  
  33.             {  
  34.                 strp = ((InvokeApple.RedApple)(ap))._dPrice.ToString();  
  35.             }  
  36. else
  37.             {  
  38.                 strp = ((InvokeApple.GreenApple)(ap))._dPrice.ToString();  
  39.             }  
  41.             Console.WriteLine("全国平均单价:" + strp);  
  43. //加上产地
  44.             Console.WriteLine("请输入产地:");  
  45. string s1 = Console.ReadLine();  
  46.             ap = Apple.CreateApple(t1, ba, s1);  
  48. if (s.Equals("红苹果"))  
  49.             {  
  50.                 strp = ((InvokeApple.RedApple)(ap))._dPrice.ToString();  
  51.             }  
  52. else
  53.             {  
  54.                 strp = ((InvokeApple.GreenApple)(ap))._dPrice.ToString();  
  55.             }  
  57.             Console.WriteLine(s1 + "单价:" + strp);  
  58.         }  
  59.     }  
  60. } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InvokeApple { class Program { static void Main(string[] args) { Console.WriteLine("您要买什么苹果？"); Console.WriteLine("请输入:"); string s = Console.ReadLine(); //需要创建的类 Type t1; string strp = ""; if (s.Equals("红苹果")) { t1 = typeof(RedApple); } else { t1 = typeof(GreenApple); } BuyApple ba = new BuyApple(); //产生所需类 Apple ap = Apple.CreateApple(t1, ba); if (s.Equals("红苹果")) { strp = ((InvokeApple.RedApple)(ap))._dPrice.ToString(); } else { strp = ((InvokeApple.GreenApple)(ap))._dPrice.ToString(); } Console.WriteLine("全国平均单价:" + strp); //加上产地 Console.WriteLine("请输入产地:"); string s1 = Console.ReadLine(); ap = Apple.CreateApple(t1, ba, s1); if (s.Equals("红苹果")) { strp = ((InvokeApple.RedApple)(ap))._dPrice.ToString(); } else { strp = ((InvokeApple.GreenApple)(ap))._dPrice.ToString(); } Console.WriteLine(s1 + "单价:" + strp); } } }
运行结果：

您要买什么苹果？
请输入:
红苹果
全国平均单价:8.5
请输入产地:
山南
山南单价:11.5
请按任意键继续. . .

posted on 2012-05-18 14:16  蓝色信仰  阅读(1583)  评论(0)    收藏  举报