嘗試使用反射為 dll 操作添加事件處理程序時，“類型為‘System.EventHandler’的對象無法轉換為類型‘System.Action’”

Question

我有以下兩個程序

Windows窗體應用程序

類庫1 dll

ClassLibrary1 dll 通過 appdomain 加載加載到 Windowsform。 我已經通過應用程序域的反射訂閱了 dll 事件。 我正在嘗試訂閱 dll 操作 (TestAction) 並處理 windows forms 中的操作。但是我收到此錯誤“類型為‘System.EventHandler’的對象無法轉換為類型‘System.Action’”

這是 windows 表單代碼：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
using System.Diagnostics;
using ClassLibrary1;

namespace WindowsFormsApplication2
{
    [Serializable]
    public partial class Form1 : Form
    {
        void HandleEvent(object sender, EventArgs e)
        {
            Debug.WriteLine("HandleEvent called");
        }
        void HandleAction(object sender, EventArgs e)
        {
            Debug.WriteLine("HandleAction called");
        }
        public Form1()
        {
            InitializeComponent();
            Loader.Call(  "RaiseEvent", HandleEvent, DateTime.Now.ToShortDateString());
            Loader.Call( "RaiseAct", HandleAction, DateTime.Now.ToShortDateString());
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Application.Restart();
            Application.Run(new Form1());
            this.Close();
        }
    }

    public class Loader : MarshalByRefObject
    {
        static string dll = @"..\ConsoleApplication1\ClassLibrary1\bin\Debug\ClassLibrary1.dll";
        static AppDomain ad = AppDomain.CreateDomain("Test");
        static Assembly a = Assembly.LoadFile(dll);
        static object o = a.CreateInstance("ClassLibrary1.Class1");
        static Type t = o.GetType();

        object CallInternal1( string method, EventHandler handler, object[] parameters)
        {
            // Subscribe to the event
            EventInfo eventInfo1 = t.GetEvent("TestEvent");
            eventInfo1.AddEventHandler(o, handler);

            MethodInfo m = t.GetMethod(method);
            return m.Invoke(o, parameters);
        }

        object CallInternal2( string method, EventHandler handler, object[] parameters)
        {
            // Subscribe to the event
            EventInfo eventInfo2 = t.GetEvent("TestAction");
            eventInfo2.AddEventHandler(o, handler);               // Error: Object of type 'System.EventHandler' cannot be converted to type 'System.Action

            MethodInfo m = t.GetMethod(method);
            return m.Invoke(o, parameters);
        }

        public static object Call( string method, EventHandler handler, params object[] parameters)
        {
            Loader ld = (Loader)ad.CreateInstanceAndUnwrap(Assembly.GetExecutingAssembly().FullName, typeof(Loader).FullName);
            object result = 0;
            switch (method)
            {
                case "RaiseEvent":
                    {
                        result = ld.CallInternal1( method, handler, parameters);
                        break;
                    }

                case "RaiseAct":
                    {
                        result = ld.CallInternal2( method, handler, parameters);
                        break;
                    }
            }
            return result;
        }
    }
}

這是ClassLibrary1.dll代碼

 using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ClassLibrary1 { [Serializable] public class Class1 { public event EventHandler TestEvent; public int RaiseEvent(string msg) { try { TestEvent(this, EventArgs.Empty); } catch (Exception ex) { Console.WriteLine("the exception is: " + ex.ToString()); if (ex.InnerException.= null) { Console:WriteLine("the inner exception is. " + ex.InnerException.Message;ToString()); } } return 2; } public event Action<int> TestAction = Func; public int RaiseAct(string msg) { TestAction(3); return 5; } public static void Func(int a) { int g = 2; } } }

Answer 1

事件的類型是Action ，因此您可以將處理程序封裝在Action中。

eventInfo2.AddEventHandler(o, new Action(() => handler(null, EventArgs.Empty)));

---

更新評論中的問題，您可以定義EventArgs的子 class 並將其傳遞給事件處理程序。

class IntEventArgs : EventArgs { public int data; }
new Action<int>((index) => handler(null, new IntEventArgs{ data = index }))