MEF 基礎簡介 三

 MEF導出類的方法和屬性

首先來說導出屬性，因為這個比較簡單，和導出類差不多，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
   {
      //導出私有屬性
      [Export(typeof(string))]
      private string _privateBookName = "Private Music BookName";

      //導出公有屬性
      [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; }

      //導入屬性，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);
      }
   }
}

下麵還用foreach遍歷輸出屬性的值，運行即可查看到結果。最後我會附上源碼供大家下載，這裡就不再截圖了。

下麵說導出方法吧，同理無論是公有方法還是私有方法都是可以導出的，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
   {
      //導出私有屬性
      [Export(typeof(string))]
      private string _privateBookName = "Private Music BookName";

      //導出公有屬性
      [Export(typeof(string))]
      public string _publicBookName = "Public Music BookName";


      public string BookName { get; set; }

      //導出公有方法
      [Export(typeof(Func<string>))]
      public string GetBookName()
      {
         return "MusicBook";
      }

      //導出私有方法
      [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; }

      //導入屬性，這裡不區分public還是private
      [ImportMany]
      public List<string> InputString { get; set; }

      //導入無參數方法
      [Import]
      public Func<string> methodWithoutPara { get; set; }

      //導入有參數方法
      [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);
      }
   }
}

導入導出方法用到了Func<T>委托，當然沒有返回值的話可以用Action<T>委托，關於委托這裡就不多說了，大家可以自行百度。