怎么通过反射获取所有继承了某一接口的类

使用 Linq:

var types = AppDomain.CurrentDomain.GetAssemblies()
    .SelectMany(a => a.GetTypes().Where(t => t.GetInterfaces().Contains(typeof(ISecurity))))
    .ToArray();

不使用 Linq：

public static IEnumerable<Type> GetType(Type interfaceType)
{
    foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
    {
        foreach (var type in assembly.GetTypes())
        {
            foreach (var t in type.GetInterfaces())
            {
                if (t == interfaceType)
                {
                    yield return type;
                    break;
                }
            }
        }
    }
}