MEF和DirectoryCatalog

Question

有沒有辦法安全地使用DirectoryCatalog來處理目錄是否存在？

這裏我的容器是如何建立一個代碼示例：

//Create an assembly catalog of the assemblies with exports 
    var catalog = new AggregateCatalog(
     new AssemblyCatalog(Assembly.GetExecutingAssembly()), 
     new AssemblyCatalog(Assembly.Load("My.Second.Assembly")), 
     new DirectoryCatalog("Plugins", "*.dll")); 

    //Create a composition container 
    var container = new CompositionContainer(catalog); 

但是，如果目錄不存在拋出一個異常，我想忽略這個錯誤。

Answer 1

顯然不是如果引發異常。只需在運行MEF容器設置之前創建目錄，然後不會拋出錯誤。

根據the documentation：

的路徑必須是絕對的或相對AppDomain.BaseDirectory。

僞碼做目錄檢查：

string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Plugins"); 

    //Check the directory exists 
    if (!Directory.Exists(path)) 
    { 
     Directory.CreateDirectory(path); 
    } 

    //Create an assembly catalog of the assemblies with exports 
    var catalog = new AggregateCatalog(
     new AssemblyCatalog(Assembly.GetExecutingAssembly()), 
     new AssemblyCatalog(Assembly.Load("My.Other.Assembly")), 
     new DirectoryCatalog(path, "*.dll")); 

    //Create a composition container 
    _container = new CompositionContainer(catalog);