c# - 使用类名和方法名调用类的成员

Question

我正在尝试使用 Reflection 调用一个类的函数(假设对象初始化不依赖于要调用的函数)

/// <summary>
    /// Calls a static public method. 
    /// Assumes that the method returns a string
    /// </summary>
    /// <param name="assemblyName">name of the assembly containing the class in which the method lives.</param>
    /// <param name="namespaceName">namespace of the class.</param>
    /// <param name="typeName">name of the class in which the method lives.</param>
    /// <param name="methodName">name of the method itself.</param>
    /// <param name="stringParam">parameter passed to the method.</param>
    /// <returns>the string returned by the called method.</returns>
    /// 
    public static string InvokeStringMethod5(string assemblyName, string namespaceName, string typeName, string methodName, string stringParam)
    {
        //This method was created incase Method has params with default values. If has params will return error and not find function
        //This method will choice and is the preffered method for invoking 

        // Get the Type for the class
        Type calledType = Type.GetType(String.Format("{0}.{1},{2}", namespaceName, typeName, assemblyName));
        String s = null;

        // Invoke the method itself. The string returned by the method winds up in s.
        // Note that stringParam is passed via the last parameter of InvokeMember, as an array of Objects.

        if (MethodHasParams(assemblyName, namespaceName, typeName, methodName))
        {
            s = (String)calledType.InvokeMember(
                        methodName,
                        BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Static,
                        null,
                        null,
                        new Object[] { stringParam });
        }
        else
        {
            s = (String)calledType.InvokeMember(
            methodName,
            BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Static,
            null,
            null,
            null);
        }

        // Return the string that was returned by the called method.
        return s;

    }

    public static bool MethodHasParams(string assemblyName, string namespaceName, string typeName, string methodName)
    {
        bool HasParams;
        string name = String.Format("{0}.{1},{2}", namespaceName, typeName, assemblyName);
        Type calledType = Type.GetType(name);
        MethodInfo methodInfo = calledType.GetMethod(methodName);
        ParameterInfo[] parameters = methodInfo.GetParameters();

        if (parameters.Length > 0)
        {
            HasParams = true;
        }
        else
        {
            HasParams = false;
        }

        return HasParams;

    }  

这取自here .

有没有其他/更好的方法来做到这一点？

这个事件可以是将军。喜欢使用Dynamic，在.Net 4.0中可以调用Non-Static methods，这样返回类型就可以独立了。

我从来没有在实际场景中使用过dynamic关键字(只看了一些例子)，实际用法我还不知道

在这方面的任何帮助/指导将不胜感激谢谢

Answer 1

回答你关于dynamic的查询；不，那不适合这里。 dynamic 在编译时已知成员名称(或操作)但无法证明其存在时很有用 - 基本上是鸭子类型。例如:

dynamic foo = GetSomeRandomObject();
foo.ThisShouldExist("abc");

这做类似的事情，但用法不同。所以是的，你留下了反射(reflection)。你在做什么是非常正确的。我唯一可能更改的是获取 MethodInfo，并从那里开始工作 - 尽管如果您可以更改 API 以接受单个 string assemblyQualifiedName 会更方便灵活。但也许:

public static string InvokeStringMethod5(string assemblyName,
    string namespaceName, string typeName, string methodName, string stringParam)
{
    string assemblyQualifiedName = string.Format("{0}.{1},{2}",
        namespaceName, typeName, assemblyName);
    Type calledType = Type.GetType(assemblyQualifiedName);
    if(calledType == null) throw new InvalidOperationException(
        assemblyQualifiedName + " not found");
    MethodInfo method = calledType.GetMethod(methodName,
        BindingFlags.Public | BindingFlags.Static);
    switch (method.GetParameters().Length)
    {
        case 0:
            return (string)method.Invoke(null, null);
        case 1:
            return (string)method.Invoke(null, new object[] { stringParam });
        default:
            throw new NotSupportedException(methodName
                + " must have 0 or 1 parameter only");
    }
}