using System;   using System.Collections.Generic;   using System.Linq;   using System.Web;   using System.Drawing;   using System.IO;   namespace BookShop.Web   {       public class WaterMark : IHttpHandler       {           private const string WATERMARK_URL = "~/Images/watermark.jpg";        //水印图片           private const string DEFAULTIMAGE_URL = "~/Images/default.jpg";<span style="white-space:pre">   </span>      //默认图片           #region IHttpHandler 成员           public bool IsReusable           {               get { return false; }           }           public void ProcessRequest(HttpContext context)           {               //context.Request.PhysicalPath  //获得用户请求的文件物理路径               System.Drawing.Image Cover;               //判断请求的物理路径中，是否存在文件               if (File.Exists(context.Request.PhysicalPath))               {                   //加载文件                   Cover = Image.FromFile(context.Request.PhysicalPath);                   //加载水印图片                   Image watermark = Image.FromFile(context.Request.MapPath(WATERMARK_URL));               //通过书的封面得到绘图对像                   Graphics g = Graphics.FromImage(Cover);                   //在image上绘制水印                   g.DrawImage(watermark, new Rectangle(Cover.Width - watermark.Width, Cover.Height - watermark.Height,    [csharp] view plaincopy watermark.Width, watermark.Height), 0, 0, watermark.Width, watermark.Height, GraphicsUnit.Pixel);                   //释放画布                   g.Dispose();                   //释放水印图片                   watermark.Dispose();               }               else              {                   //加载默认图片                   Cover = Image.FromFile(context.Request.MapPath(DEFAULTIMAGE_URL));               }               //设置输出格式               context.Response.ContentType = "image/jpeg";               //将图片存入输出流               Cover.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);               Cover.Dispose();               context.Response.End();           }           #endregion       }   }