您可以将第二个通用参数添加到实现类中.下面的静态 Example 方法显示了此示例.

You can add the second generic parameter to the implementation class. The static Example method below shows an example of this.

public interface ITest<T>
{
    T GetValue();
}

public class Test<T, U> where T : ITest<U>
{
    public U GetValue(T input)
    {
        return input.GetValue();
    }
}

public class Impl : ITest<string>
{
    public string GetValue()
    {
        return "yay!";
    }

    public static void Example()
    {
        Test<Impl, string> val = new Test<Impl,string>();
        string result = val.GetValue(new Impl());
    }
}