MEF在运行时替换插件

利用AppDomain的ShadowCopy特性。

 var setup = new AppDomainSetup
        {
            CachePath = cachePath,
            ShadowCopyFiles = "true",
            ShadowCopyDirectories = pluginPath
        };

 创建程序集

domain = AppDomain.CreateDomain("Host_AppDomain", AppDomain.CurrentDomain.Evidence, setup); 
var asmfullname = typeof(UseConfig).Assembly.FullName; 
var typefullname = typeof(UseConfig).FullName; 
useConfig = (UseConfig)domain.CreateInstanceAndUnwrap(asmfullname, typefullname); 
useConfig.Build();

 在创建好的程序集里通过MEF加载插件

useConfig.cs: public void Build() 
{ 
var regBuilder = new RegistrationBuilder(); 
regBuilder.ForTypesDerivedFrom<IConfig>().Export<IConfig>(); 
var catalog = new AggregateCatalog(); 
catalog.Catalogs.Add(new AssemblyCatalog(typeof(UseConfig).Assembly, regBuilder)); 
directoryCatalog = new DirectoryCatalog(pluginPath, regBuilder); 
catalog.Catalogs.Add(directoryCatalog); 
container = new CompositionContainer(catalog); 
container.ComposeExportedValue(container); 
configs = container.GetExportedValues<IConfig>();
 }

替换插件

1. 先删除后添加
   刷新一下，重新输出。
   public void Recompose()
   {
   directoryCatalog.Refresh();
   container.ComposeParts(directoryCatalog.Parts);
   configs = container.GetExportedValues<IConfig>();
   }

2. 直接替换
   通过FileWatch监视，一旦有文件变化Unload AppDomain，然后重新加载。