C#可擴充編程之MEF學習筆記（三）：匯出類的方法和屬性

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前面說完了匯入和匯出的幾種方法，如果大家細心的話會注意到前面我們匯出的都是類，那麼方法和屬效能不能匯出呢？？？答案是肯定的，下面就來說下MEF是如何匯出方法和屬性的。

　　還是前面的代碼，第二篇中已經提供了下載連結，大家可以下載學習。

　　首先來說匯出屬性，因為這個比較簡單，和匯出類差不多，先來看看代碼，主要看我加註釋的地方，MusicBook.cs中的代碼如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.ComponentModel.Composition;namespace MEFDemo{   [Export("MusicBook")]   public class MusicBook : IBookService   {      //匯出私人屬性      [Export(typeof(string))]      private string _privateBookName = "Private Music BookName";      //匯出公有屬性      [Export(typeof(string))]      public string _publicBookName = "Public Music BookName";      public string BookName { get; set; }   }   [Export("MathBook", typeof(IBookService))]   public class MathBook : IBookService   {      public string BookName { get; set; }      public string GetBookName()      {         return "MathBook";      }   }   [Export("HistoryBook", typeof(IBookService))]   public class HistoryBook : IBookService   {      public string BookName { get; set; }      public string GetBookName()      {         return "HistoryBook";      }   }}

program.cs中的代碼如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Reflection;using System.ComponentModel.Composition;using System.ComponentModel.Composition.Hosting;namespace MEFDemo{   class Program   {      [ImportMany("MathBook")]      public IEnumerable<object> Services { get; set; }      //匯入屬性，這裡不區分public還是private      [ImportMany]      public List<string> InputString { get; set; }      static void Main(string[] args)      {         Program pro = new Program();         pro.Compose();         if (pro.Services != null)         {            foreach (var s in pro.Services)            {               var ss = (IBookService)s;               Console.WriteLine(ss.GetBookName());            }         }         foreach (var str in pro.InputString)         {            Console.WriteLine(str);         }         Console.Read();      }            private void Compose()      {         var catalog = new AssemblyCatalog(Assembly.GetExecutingAssembly());         CompositionContainer container = new CompositionContainer(catalog);         container.ComposeParts(this);      }   }}

下面還用foreach遍曆輸出屬性的值，運行即可查看到結果。最後我會附上源碼供大家下載，這裡就不再了。

下面說匯出方法吧，同理無論是公有方法還是私人方法都是可以匯出的，MusicBook代碼如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.ComponentModel.Composition;namespace MEFDemo{   [Export("MusicBook")]   public class MusicBook : IBookService   {      //匯出私人屬性      [Export(typeof(string))]      private string _privateBookName = "Private Music BookName";      //匯出公有屬性      [Export(typeof(string))]      public string _publicBookName = "Public Music BookName";      public string BookName { get; set; }      //匯出公有方法      [Export(typeof(Func<string>))]      public string GetBookName()      {         return "MusicBook";      }      //匯出私人方法      [Export(typeof(Func<int, string>))]      private string GetBookPrice(int price)      {         return "$" + price;      }   }   [Export("MathBook", typeof(IBookService))]   public class MathBook : IBookService   {      public string BookName { get; set; }      public string GetBookName()      {         return "MathBook";      }   }   [Export("HistoryBook", typeof(IBookService))]   public class HistoryBook : IBookService   {      public string BookName { get; set; }      public string GetBookName()      {         return "HistoryBook";      }   }}

program中的代碼如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Reflection;using System.ComponentModel.Composition;using System.ComponentModel.Composition.Hosting;namespace MEFDemo{   class Program   {      [ImportMany("MathBook")]      public IEnumerable<object> Services { get; set; }      //匯入屬性，這裡不區分public還是private      [ImportMany]      public List<string> InputString { get; set; }      //匯入無參數方法      [Import]      public Func<string> methodWithoutPara { get; set; }      //匯入有參數方法      [Import]      public Func<int,string> methodWithPara { get; set; }      static void Main(string[] args)      {         Program pro = new Program();         pro.Compose();         if (pro.Services != null)         {            foreach (var s in pro.Services)            {               var ss = (IBookService)s;               Console.WriteLine(ss.GetBookName());            }         }         foreach (var str in pro.InputString)         {            Console.WriteLine(str);         }         //調用無參數方法         if (pro.methodWithoutPara != null)         {            Console.WriteLine(pro.methodWithoutPara());         }         //調用有參數方法         if (pro.methodWithPara != null)         {            Console.WriteLine(pro.methodWithPara(3000));         }         Console.Read();      }            private void Compose()      {         var catalog = new AssemblyCatalog(Assembly.GetExecutingAssembly());         CompositionContainer container = new CompositionContainer(catalog);         container.ComposeParts(this);      }   }}

匯入匯出方法用到了Func<T>委託，當然沒有傳回值的話可以用Action<T>委託，關於委託這裡就不多說了，大家可以自行百度。

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C#可擴充編程之MEF學習筆記（三）：匯出類的方法和屬性（轉）