C#可扩展编程之MEF（三）：导出类的方法和属性

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前面说完了导入和导出的几种方法，如果大家细心的话会注意到前面我们导出的都是类，那么方法和属性能不能导出呢？？？答案是肯定的，下面就来说下MEF是如何导出方法和属性的。

还是前面的代码，第二篇中已经提供了下载链接，大家可以下载学习。

首先来说导出属性，因为这个比较简单，和导出类差不多，先来看看代码，主要看我加注释的地方，MusicBook.cs中的代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel.Composition;namespace MEFDemo
{
[Export("MusicBook")]
public class MusicBook : IBookService
{
//导出私有属性
[Export(typeof(string))]
private string _privateBookName = "Private Music BookName"; //导出公有属性
[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中的代码如下：

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; } //导入属性，这里不区分public还是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);
}
}
}

下面还用foreach遍历输出属性的值，运行即可查看到结果。最后我会附上源码供大家下载，这里就不再截图了。

下面说导出方法吧，同理无论是公有方法还是私有方法都是可以导出的，MusicBook代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel.Composition;namespace MEFDemo
{
[Export("MusicBook")]
public class MusicBook : IBookService
{
//导出私有属性
[Export(typeof(string))]
private string _privateBookName = "Private Music BookName"; //导出公有属性
[Export(typeof(string))]
public string _publicBookName = "Public Music BookName"; public string BookName { get; set; } //导出公有方法
[Export(typeof(Func<string>))]
public string GetBookName()
{
return "MusicBook";
} //导出私有方法
[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中的代码如下：

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; } //导入属性，这里不区分public还是private
[ImportMany]
public List<string> InputString { get; set; } //导入无参数方法
[Import]
public Func<string> methodWithoutPara { get; set; } //导入有参数方法
[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);
} //调用无参数方法
if (pro.methodWithoutPara != null)
{
Console.WriteLine(pro.methodWithoutPara());
}
//调用有参数方法
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);
}
}
}