构建可扩展程序

简要说明：可扩展程序包括三个部分，第一部分是个接口程序，包含IAppFunctionality接口，所有扩展都要实现该接口，第二部分是扩展，实现IAppFunctionality，第三部分是主程序，它检测与它同级目录下是否有plugins文件夹，如果没有，就创建，如果有，查找该目录下所有实现IAppFunctionality接口的程序集，并更新菜单。
 
未添加扩展（即plugins下无dll程序)的运行情况

未安装插件的效果

安装插件之后

安装了插件后菜单发生了变化

点击Plugin1和Plugin2：

程序源码：

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//AuthorInfoAttribute.cs
using System;
 
namespace PluginBase
{
    public interface IAppFunctionality
    {
        void ShowInfo();
    }
 
    [AttributeUsage(AttributeTargets.Class)]
    public class AuthorInfoAttribute : System.Attribute
    {
        public string Email { get; set; }
        public string Name { get; set; }
    }
}
 
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//Plugin1.cs
using System.Windows.Forms;
using PluginBase;
 
namespace Plugin1
{
    [AuthorInfoAttribute(Name="liulixiang", Email="liulixiang1988@gmail.com")]
    public class Plugin1: IAppFunctionality
    {
        public void ShowInfo()
        {
            MessageBox.Show("Hello world, 你懂的。");
        }
    }
}
 
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//Plugin2.cs
using System.Windows.Forms;
using PluginBase;
 
namespace Plugin2
{
    [AuthorInfoAttribute(Name="liulixiang", Email="liulixiang1988@gmail.com")]
    public class Plugin2:IAppFunctionality
    {
        public void ShowInfo()
        {
            MessageBox.Show("打酱油~~~");
        }
    }
}
 
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//MainApp.cs
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Windows.Forms;
using PluginBase;
 
namespace MyExtendableApp
{
    public partial class MainApp : Form
    {
        private string pluginDir = "plugins\\";
        private List<PluginBase.IAppFunctionality> apps = new List<PluginBase.IAppFunctionality>();
        public MainApp()
        {
            InitializeComponent();
            LoadPlugins();
        }
 
        private void LoadPlugins()
        {
            if (!Directory.Exists(pluginDir))
            {
                // 如果扩展程序文件夹不存在，就创建它
                Directory.CreateDirectory(pluginDir);
            }
 
            try
            {
	            var plugins = from plugin in Directory.EnumerateFiles(pluginDir, "*.dll")
	                          select plugin;
	            foreach (string plugin in plugins)
	            {
                    Assembly thePluginAsm = null;
                     thePluginAsm = Assembly.LoadFrom(plugin);
 
                    //获取所有实现扩展接口的程序集
                     var theClassTypes = from t in thePluginAsm.GetTypes()
                                        where t.IsClass && (t.GetInterface("IAppFunctionality") != null)
                                        select t;
 
                    //调用接口方法
                    foreach (Type t in theClassTypes)
                    {
                        IAppFunctionality itfApp = (IAppFunctionality)thePluginAsm.CreateInstance(t.FullName, true);
                        apps.Add(itfApp);
                        ToolStripMenuItem menuItem = new ToolStripMenuItem(t.Name);
                        menuItem.Click += new System.EventHandler(delegate(object o, EventArgs e)
                            {
                                itfApp.ShowInfo();
                            });
                        menuStrip1.Items.Add(menuItem);
                      //  itfApp.ShowInfo();
                    }
	            }
 
 
            }
            catch (System.Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }
}
posted @ 2011-06-02 10:30  刘理想  阅读(853)  评论(2)  编辑  收藏  举报