/// <summary>/// 实现URL的重写/// </summary>public class UrlRewriteModule : IHttpModule{#region IHttpModule 成员public void Init(HttpApplication context){context.BeginRequest += new EventHandler(Application_BeginRequest);}/// <summary>/// url重写/// .png?w=100&h=100/// _100x100.png/// </summary>/// <param name="sender"></param>/// <param name="e"></param>protected void Application_BeginRequest(Object sender, EventArgs e){string oldUrl = HttpContext.Current.Request.RawUrl;if (oldUrl.LastIndexOf(".") > -1){string ext = oldUrl.Substring(oldUrl.LastIndexOf(".")).ToLower();//是图像文件if (ext == ".jpg"||ext == ".jpeg"||ext == ".png"||ext == "gif"){var param = oldUrl.Substring(oldUrl.LastIndexOf("_") + 1, (oldUrl.IndexOf(".") - oldUrl.LastIndexOf("_") - 1)).Split(new char[] { 'x' }, StringSplitOptions.RemoveEmptyEntries);//有图像缩放请求if (oldUrl.LastIndexOf("_") > -1){string newUrl = oldUrl.Substring(0, oldUrl.LastIndexOf("_"));newUrl = string.Format(newUrl + ext + "?w={0}&h={1}", param[0], param[1]);//将请求中的URL进行重写
                        HttpContext.Current.RewritePath(newUrl);}}}}#endregion#region IHttpModule 成员public void Dispose(){}#endregion}

    /// <summary>/// 图片动态缩放处理程序/// </summary>public class ImageScalingHandler : IHttpHandler{/// <summary>/// 图像等比例缩放，图像默认为白色/// </summary>/// <param name="image"></param>/// <param name="width"></param>/// <param name="height"></param>/// <returns></returns>private Bitmap CreateThumbnail(Image image, int width, int height){Point point = new Point(0, 0); //图像从那个坐标点进行截取double wRate = 1, hRate = 1, setRate = 1;int newWidth = 0, newHeight = 0;try{if (width == 0) width = image.Width;if (height == 0) height = image.Height;if (image.Height > height){hRate = (double)height / image.Height;}if (image.Width > width){wRate = (double)width / image.Width;}if (wRate != 1 || hRate != 1){if (wRate > hRate){setRate = hRate;}else{setRate = wRate;}}newWidth = (int)(image.Width * setRate);newHeight = (int)(image.Height * setRate);if (height > newHeight){point.Y = Convert.ToInt32(height / 2 - newHeight / 2);}if (width > newWidth){point.X = Convert.ToInt32(width / 2 - newWidth / 2);}Bitmap bit = new Bitmap(width, height);Rectangle r = new Rectangle(point.X, point.Y, (int)(image.Width * setRate), (int)(image.Height * setRate));Graphics g = Graphics.FromImage(bit);g.Clear(Color.White);g.DrawImage(image, r);g.Dispose();return bit;}catch (Exception){throw;}}/// <summary>/// 处理请求/// </summary>/// <param name="context"></param>public void ProcessRequest(HttpContext context){int w = 0, h = 0;int.TryParse(context.Request.QueryString["w"], out w);int.TryParse(context.Request.QueryString["h"], out h);Image image = Image.FromFile(context.Request.PhysicalPath);context.Response.ContentType = "image/jpeg";Bitmap bitMap = CreateThumbnail(image, w, h);bitMap.Save(context.Response.OutputStream, ImageFormat.Jpeg);image.Dispose();bitMap.Dispose();context.Response.End();}public bool IsReusable{get { return false; }}}

 <system.web><httpModules><!-- this is for Classic mode and Cassini --><add name="UrlRewriteModule" type="EntityFrameworks.Web.Core.HttpModules.UrlRewriteModule,EntityFrameworks.Web.Core" /></httpModules></system.web>

<system.webServer><modules runAllManagedModulesForAllRequests="true" ><!--This is for Integrated mode--><add name="UrlRewriteModule" type="EntityFrameworks.Web.Core.HttpModules.UrlRewriteModule,EntityFrameworks.Web.Core" /></modules><handlers><add name="ImageFunction1" path="*.jpg" verb="GET" type="EntityFrameworks.Web.Core.HttpHandlers.ImageScalingHandler,EntityFrameworks.Web.Core"  /><add name="ImageFunction2" path="*.png" verb="GET" type="EntityFrameworks.Web.Core.HttpHandlers.ImageScalingHandler,EntityFrameworks.Web.Core"  /><add name="ImageFunction3" path="*.gif" verb="GET" type="EntityFrameworks.Web.Core.HttpHandlers.ImageScalingHandler,EntityFrameworks.Web.Core"  /><add name="ImageFunction4" path="*.jpeg" verb="GET" type="EntityFrameworks.Web.Core.HttpHandlers.ImageScalingHandler,EntityFrameworks.Web.Core"  />
</handlers>