如何在具有特定名称的当前程序集中查找 C# 接口的实现？
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How to find an implementation of a C# interface in the current assembly with a specific name?
提问by Daren Thomas
I have an Interface called IStepthat can do some computation (See "Execution in the Kingdom of Nouns"). At runtime, I want to select the appropriate implementation by class name.
我有一个接口IStep，可以进行一些计算（请参阅“名词王国中的执行”）。在运行时，我想通过类名选择适当的实现。
// use like this: IStep step = GetStep(sName);
采纳答案by lubos hasko
Your question is very confusing...
你的问题好纠结。。。
If you want to find types that implement IStep, then do this:
如果要查找实现 IStep 的类型，请执行以下操作：
foreach (Type t in Assembly.GetCallingAssembly().GetTypes())
{
if (!typeof(IStep).IsAssignableFrom(t)) continue;
Console.WriteLine(t.FullName + " implements " + typeof(IStep).FullName);
}
If you know already the name of the required type, just do this
如果您已经知道所需类型的名称，请执行此操作
IStep step = (IStep)Activator.CreateInstance(Type.GetType("MyNamespace.MyType"));
回答by Ian Nelson
If the implementation has a parameterless constructor, you can do this using the System.Activator class. You will need to specify the assembly name in addition to the class name:
如果实现具有无参数构造函数，则可以使用 System.Activator 类来执行此操作。除了类名之外，您还需要指定程序集名称：
IStep step = System.Activator.CreateInstance(sAssemblyName, sClassName).Unwrap() as IStep;
http://msdn.microsoft.com/en-us/library/system.activator.createinstance.aspx
http://msdn.microsoft.com/en-us/library/system.activator.createinstance.aspx
回答by Daren Thomas
Based on what others have pointed out, this is what I ended up writing:
根据其他人所指出的，这就是我最终写的：
///
/// Some magic happens here: Find the correct action to take, by reflecting on types
/// subclassed from IStep with that name.
///
private IStep GetStep(string sName)
{
Assembly assembly = Assembly.GetAssembly(typeof (IStep));
try
{
return (IStep) (from t in assembly.GetTypes()
where t.Name == sName && t.GetInterface("IStep") != null
select t
).First().GetConstructor(new Type[] {}
).Invoke(new object[] {});
}
catch (InvalidOperationException e)
{
throw new ArgumentException("Action not supported: " + sName, e);
}
}
回答by samjudson
Well Assembly.CreateInstance would seem to be the way to go - the only problem with this is that it needs the fully qualified name of the type, i.e. including the namespace.
那么 Assembly.CreateInstance 似乎是要走的路 - 唯一的问题是它需要类型的完全限定名称，即包括命名空间。
