C# MEF 通用插件框架

首先看下接口约定：

namespace PluginContract
{
    public interface IPlugin
    {
        string Name { get; set; }
        void SayHello();
    }
    public interface IPluginMark
    {
        string Mark { get; }
    }
}

自动加载插件类：

    public class PlugerBase<T>
    {
        public T GetClass(string className)
        {
            if (Names.Contains(className))
            {
                var plug = DoPluginList.Where(i => i.Metadata.Mark == className).Select(p => p.Value).FirstOrDefault();
                return (T)plug;
            }
            else
            {
                return default(T);
            }
        }
        public string[] Names
        {
            get
            {
                List<string> name = new List<string>();
                foreach (var item in DoPluginList)
                {
                    name.Add(item.Metadata.Mark);
                }
                return name.ToArray();
            }
        }
        /// <summary>
        /// 插件列表
        /// </summary>
        [ImportMany]
        private List<Lazy<T, IPluginMark>> DoPluginList = new List<Lazy<T, IPluginMark>>();
        public PlugerBase(string subFolderName="Plug")
        {
            Directory.CreateDirectory(Environment.CurrentDirectory + "\\"+ subFolderName);
            var catelog = new AggregateCatalog();
            AssemblyCatalog assemblyCataLog = new AssemblyCatalog(Assembly.GetExecutingAssembly());
            catelog.Catalogs.Add(new DirectoryCatalog(subFolderName));
            var container = new CompositionContainer(catelog);
            container.ComposeParts(this);
        }
    }

插件端：

第一个：

namespace MEF_Demo//第一个插件实现的插件需要被调用应用的命名空间一致，切记
{
    [ExportMetadata("Mark", "2")]//Mark需要和接口名称同步IPluginMark.后面的2便是GetClass(string className)的className
    [Export(typeof(IPlugin))]
    public class PluginFirst : IPlugin
    {
        public string Name { get; set; } = "张三";
 
        public void SayHello()
        {
            MessageBox.Show($"你好啊{Name}");
        }
    }
}

第二个：

namespace MEF_Demo
{
    [ExportMetadata("Mark","1")]
    [Export(typeof(IPlugin))]
    public class PluginSecod : IPlugin
    {
        public string Name { get; set; } = "李四";
        public void SayHello()
        {
            MessageBox.Show($"你好啊{Name}");
        }
    }
}

最后调用时非常简单：

 public MainWindow()
 {
    InitializeComponent();
    PlugerBase<IPlugin> plug = new PlugerBase<IPlugin>();//编译好的插件需要放置在Plug文件夹内
    var d= plug.GetClass("1");//通过名称直接反射出对应的类
    d.SayHello();
 }