MEF 和目录目录

Question

如果目录不存在，有没有办法安全地使用 DirectoryCatalog 来处理？

这里是我的容器如何设置的代码示例：

    //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);

但是如果目录不存在就会抛出异常，我想忽略这个错误。

Answer 1

如果抛出异常，显然不会。只需在运行 MEF 容器设置之前创建目录，就不会抛出错误。

根据the documentation：

路径必须是绝对的或相对于AppDomain.BaseDirectory。

PsuedoCode 做目录检查：

    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);