先看这个demo的解决方案图

Entity是实体，里面有验证码的实体

        private string contentType = "image/pjpeg";private ImageFormat imageFormat = ImageFormat.Jpeg;public Bitmap Image{get;set;}public string ContentType{get { return contentType; }set { contentType = value; }}public ImageFormat ImageFormat{get { return imageFormat; }set { imageFormat = value; }}

Plugin是插件
这个验证码是插件机制实现的
接口文件为

    public interface IVerifyImage{VerifyImageInfo GenerateImage(string code, int width, int height, Color bgcolor, int textcolor);}

provider类是一个抽象工厂
代码为

        private static Hashtable _instance = new Hashtable();private static object lockHelper = new object();//通过接口和反射结合配置文件信息来做整站多验证码技术public static IVerifyImage GetInstance(string assemlyName){if (!_instance.Contains(assemlyName)){lock (lockHelper){if (!_instance.ContainsKey(assemlyName)){IVerifyImage p = null;try{p = (IVerifyImage)Activator.CreateInstance(Type.GetType(string.Format("Plugin.VerifyImage.{0}.VerifyImage,Plugin.VerifyImage.{0}", assemlyName), false, true));}catch{p = new Plugin.VerifyImage.JpegImage.VerifyImage();}_instance.Add(assemlyName, p);}}}return (IVerifyImage)_instance[assemlyName];}

验证码相关对象是通过发射机制创建的
具体路径信息写在配置文件中
这样可以设置多个验证码类

具体验证码相关代码请下载这个demo自己去研究

做一个页面,重写他的onInit事件，把验证码输出出来

        protected override void OnInit(EventArgs e){base.OnInit(e);string verifyAssembly = "JpegImage";//此处信息可从配置文件获得string bgColor = "";//Request.QueryString["bgcolor"].Trim();int fontColor = 1; //StrToInt(Request.QueryString["fontcolor"].Trim(), 1);string[] bgcolorArray = bgColor.Split(',');Color bg = Color.White;if (bgcolorArray.Length == 1 && bgColor != string.Empty){bg = ToColor(bgColor);}else if (bgcolorArray.Length == 3 && IsNumericArray(bgcolorArray)){bg = Color.FromArgb(StrToInt(bgcolorArray[0], 255), StrToInt(bgcolorArray[1], 255), StrToInt(bgcolorArray[2], 255));}VerifyImageInfo verifyimg = Plugin.VerifyImage.VerifyImageProvider.GetInstance(verifyAssembly).GenerateImage(CreateAuthStr(5, false), 120, 60, bg, fontColor);Bitmap image = verifyimg.Image;System.Web.HttpContext.Current.Response.ContentType = verifyimg.ContentType;//MemoryStream ms = new MemoryStream();image.Save(this.Response.OutputStream, verifyimg.ImageFormat);}

这里涉及到很多工具方法，请下载demo自己研究

调用验证码可以在页面写JS代码

<script type="text/javascript">document.getElementById('vcodeimg').src='/tools/VerifyImagePage.aspx?id=4&time=' + Math.random();
</script>

源代码下载
vertify.rar