namespace IMsg{    ///<summary>    /// 这是插件必须实现的接口，也是主程序与插件通信的唯一接口    /// 换句话说，主程序只认识插件里的这些方法    ///</summary>    public interface IMsgPlug    {        /// <summary>        /// 显示窗体        /// </summary>        void OnShowDlg();        /// <summary>        /// 显示信息        /// </summary>        /// <returns></returns>        string OnShowInfo();    }}

using IMsg;using System;namespace MYPlugin1{    public class myConsole : IMsgPlug    {        #region IMsgPlug 成员        public void OnShowDlg()        {            Console.WriteLine("控制台调用插件的OnShowDlg方法");        }        public string OnShowInfo()        {            return "myConsole";        }        #endregion    }}

using IMsg;using System.Windows.Forms;namespace MYPlugin1{    public class MYDlg : Form, IMsgPlug    {        #region IMsgPlug 成员        public void OnShowDlg()        {            this.Text = "插件子窗体";            this.ShowDialog();//调用Form的ShowDialog,显示窗体        }        public string OnShowInfo()        {            return "MyDlg";        }        #endregion    }}

using System;using System.Collections;using System.IO;using System.Reflection;using System.Windows.Forms;namespace MsgBoxMain{    public partial class FormMain : Form    {        ///<summary>        /// 存放插件的集合        ///</summary>        private ArrayList plugins = new ArrayList();        public FormMain()        {            InitializeComponent();        }        ///<summary>        /// 载入所有插件        ///</summary>        private void LoadAllPlugs()        {            //获取插件目录(plugins)下所有文件夹            DirectoryInfo dirs = new DirectoryInfo(Application.StartupPath + @"\Plugins");            foreach (DirectoryInfo dir in dirs.GetDirectories())            {                //获取文件夹下文件                string[] files = Directory.GetFiles(dir.FullName);                foreach (string file in files)                {                    if (file.ToUpper().EndsWith(".DLL"))                    {                        try                        {                            //载入dll                            Assembly ab = Assembly.LoadFrom(file);                            Type[] types = ab.GetTypes();                            foreach (Type t in types)                            {                                //如果某些类实现了预定义的IMsg.IMsgPlug接口，则认为该类适配与主程序(是主程序的插件)                                if (t.GetInterface("IMsgPlug") != null)                                {                                    plugins.Add(ab.CreateInstance(t.FullName));                                    listBox1.Items.Add(t.FullName);                                }                            }                        }                        catch (Exception ex)                        {                            MessageBox.Show(ex.Message);                        }                    }                }            }        }        private void btnLoadPlug_Click(object sender, EventArgs e)        {            LoadAllPlugs();        }        //调用插件的方法        private void btnExecute_Click(object sender, EventArgs e)        {            if (this.listBox1.SelectedIndex == -1) return;            object selObj = this.plugins[this.listBox1.SelectedIndex];            Type t = selObj.GetType();            MethodInfo OnShowDlg = t.GetMethod("OnShowDlg");            MethodInfo OnShowInfo = t.GetMethod("OnShowInfo");            OnShowDlg.Invoke(selObj, null);            object returnValue = http://www.mamicode.com/OnShowInfo.Invoke(selObj, null);            this.lblMsg.Text = returnValue.ToString();        }    }}