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首先建一个类：  。

复制代码代码如下

using System;  using System.Collections.Generic;  using System.Linq;  using System.Web;  using System.Drawing;  /// <summary>  ///Class1 的摘要说明  /// </summary>  public class Class1:IHttpHandler //调用接口  {  public Class1()  {  //  //TODO: 在此处添加构造函数逻辑  //  }  public bool IsReusable  {  get { return true; }  }  public void ProcessRequest(HttpContext context)  {  HttpRequest req = context.Request;  if (req.UrlReferrer != null && req.UrlReferrer.Host.Length > 0) //反盗链代码判断  {  System.Drawing.Image img = System.Drawing.Image.FromFile(context.Request.PhysicalPath);  System.Drawing.Graphics g = Graphics.FromImage(img);  g.DrawString("三国演义", new Font("宋体", 20, FontStyle.Bold), Brushes.White, 10, 10);  img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);  context.Response.Flush();  context.Response.End();  }  else  {  context.Response.Write("您不能盗链本站图片");  }  }  }  。

在web.config中注册接口：  。

复制代码代码如下

<httpHandlers>  <add verb="*" path="images/*.jpg" type="Class1,App_Code"/>  </httpHandlers>  。

url:http://greatverve.cnblogs.com/archive/2011/12/20/asp-net-hotlinking.html  参考：  1.修改web.config  。

复制代码代码如下

<system.web>  <httpHandlers>  <remove verb="*" path="*.asmx"/>  <!--解决图片防盗链问题-->  <add verb="*" path="*.jpg" type="MyHttpHandler.Watermark"/>  <add verb="*" path="*.gif" type="MyHttpHandler.Watermark"/>  <add verb="*" path="*.png" type="MyHttpHandler.Watermark"/>  </httpHandlers>  </system.web>  。

2.添加一个一般执行文件Watermark.ashx，代码如下：  。

复制代码代码如下

using System;  using System.Data;  using System.Web;  using System.Collections;  using System.Web.Services;  using System.Web.Services.Protocols;  using System.Drawing.Imaging;  using System.Drawing;  using System.IO;  namespace MyHttpHandler  {  /// <summary>  /// Summary description for $codebehindclassname$  /// </summary>  [WebService(Namespace = "http://tempuri.org/")]  [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]  public class Watermark : IHttpHandler  {  public bool IsReusable  {  get  {  return false;  }  }  public void ProcessRequest(HttpContext context)  {  //设置客户端缓冲时间过期时间为0，即立即过期  //context.Response.Expires = 0;  //清空服务器端为此会话开启的输出缓存  //context.Response.Clear();  //设置输出文件类型  context.Response.ContentType = "image/jpg";  //将请求文件写入到输出缓存中  #region 获取XML配置信息  DataSet dsConfing = new DataSet();  string watermarkConfigPath = context.Server.MapPath("~/Config/WaterMarkConfig.xml");  if (System.IO.File.Exists(watermarkConfigPath))  dsConfing.ReadXml(watermarkConfigPath);  else  {  //添加默认的水印配置  }  DataRow drConfing = dsConfing.Tables[0].Rows[0];  #endregion  string currentHost = drConfing["allowhost"].ToString();  //判断是否是本地网站引用图片，如果是则返回正确的图片  if (context.Request.Url.Authority.Equals(currentHost, StringComparison.InvariantCultureIgnoreCase))  {  string localPath = context.Request.Url.LocalPath;  localPath = localPath.Remove(localPath.LastIndexOf('/')).ToLower();// "/images/userphoto"  if (drConfing["isflag"].Equals("true") && drConfing["files"].ToString().ToLower().IndexOf(localPath) > 0)  {  #region 水印代码  string sImgStartPhysicalPath = context.Request.PhysicalPath;  System.Drawing.Image imgStart = System.Drawing.Image.FromFile(sImgStartPhysicalPath);  //备份原图片  //int indexOf = sImgStartPhysicalPath.LastIndexOf(".");  //string bakPath = sImgStartPhysicalPath.Remove(indexOf) + "_bak" + sImgStartPhysicalPath.Substring(indexOf);  //imgStart.Save(bakPath);  Graphics gh = System.Drawing.Graphics.FromImage(imgStart);  if (drConfing["type"].Equals("img"))  {  System.Drawing.Image imgWatermark = System.Drawing.Image.FromFile(context.Server.MapPath(drConfing["img-path"].ToString()));  Rectangle rg = SetImgPosition(drConfing["position"].ToString(), imgStart.Width, imgStart.Height, imgWatermark.Width, imgWatermark.Height);  gh.DrawImage(imgWatermark, rg, 0, 0, imgWatermark.Width, imgWatermark.Height, GraphicsUnit.Pixel);  gh.Save();  gh.Dispose();  imgWatermark.Dispose();  }  else if (drConfing["type"].Equals("font"))  {  //文字水印  string content = drConfing["font-content"].ToString();  float Size = (float)Convert.ToDouble(drConfing["font-size"].ToString());  FontStyle fontStyle = (FontStyle)int.Parse(drConfing["font-style"].ToString());  System.Drawing.Font f = new System.Drawing.Font("Arial", Size, fontStyle);  Color G_Color = Color.FromName(drConfing["font-color"].ToString());  System.Drawing.Brush b = new System.Drawing.SolidBrush(G_Color);  SizeF sizeF = gh.MeasureString(content, f);  gh.DrawString(content, f, b, SetFontPosition(drConfing["position"].ToString(), imgStart.Width, imgStart.Height, (int)sizeF.Width, (int)sizeF.Height));  gh.Save();  gh.Dispose();  }  //将请求文件写入到输出缓存中  imgStart.Save(context.Response.OutputStream, ImageFormat.Jpeg);  imgStart.Dispose();  #endregion  }  else  {  #region 输出原图  //将请求文件写入到输出缓存中  context.Response.WriteFile(context.Request.Url.AbsolutePath);  #endregion  }  }  //如果不是本地引用，则是盗链本站图片  else  {  //将请求文件写入到输出缓存中  context.Response.WriteFile(context.Request.PhysicalApplicationPath + drConfing["errimgpath"].ToString());  }  //将输出缓存中的信息传送到客户端  context.Response.End();  }  /// <summary>  /// 图片绘画水印的位置  /// </summary>  /// <param name="positionConfig">位置类型</param>  /// <param name="width">原图片宽</param>  /// <param name="height"></param>  /// <param name="watermarkWidth">水印图宽</param>  /// <param name="watermarkHeight"></param>  /// <returns></returns>  private Rectangle SetImgPosition(string positionConfig,int width,int height,int watermarkWidth,int watermarkHeight)  {  int xpos = 0;  int ypos = 0;  int margin = 10;  int width_margin = width - margin;  int height_margin = height - margin;  double proportion = 1d;//水印图片缩放比例  //int  if ((width_margin > watermarkWidth * proportion) && (height_margin > watermarkHeight * proportion))  {  }  else if ((width_margin > watermarkWidth * proportion) && (height_margin < watermarkHeight * proportion))  {  proportion = Convert.ToDouble( height_margin) / Convert.ToDouble( watermarkHeight);  }  else if ((width_margin < watermarkWidth * proportion) && (height_margin > watermarkHeight * proportion))  {  proportion = Convert.ToDouble(width_margin) / Convert.ToDouble(watermarkWidth);  }  else  {  double proportionW = Convert.ToDouble(width_margin) / Convert.ToDouble(watermarkWidth);  double proportionH = Convert.ToDouble(height_margin) / Convert.ToDouble(watermarkHeight);  proportion = proportionW >= proportionH ? proportionH : proportionW;  }  watermarkWidth = Convert.ToInt32(watermarkWidth * proportion);  watermarkHeight = Convert.ToInt32(watermarkHeight * proportion);  switch (positionConfig)  {  case "top-left":  xpos = margin;  ypos = margin;  break;  case "top-right":  xpos = width_margin - watermarkWidth;  ypos = margin;  break;  case "bottom-left":  xpos = margin;  ypos = height_margin - watermarkHeight;  break;  case "bottom-right":  xpos = width_margin - watermarkWidth ;  ypos = height_margin - watermarkHeight ;  break;  default:  xpos = width_margin - watermarkWidth ;  ypos = height_margin - watermarkHeight;  break;  }  return new Rectangle(xpos,ypos,watermarkWidth,watermarkHeight);  }  /// <summary>  /// 图片绘画文字位置  /// </summary>  /// <param name="positionConfig">位置类型</param>  /// <param name="width">原图片宽</param>  /// <param name="height"></param>  /// <param name="fontWidth">文字长度</param>  /// <param name="fontHeight"></param>  /// <returns></returns>  private Point SetFontPosition(string positionConfig, int width, int height, int fontWidth, int fontHeight)  {  int xpos = 0;  int ypos = 0;  int margin = 10;  int width_margin = width - margin;  int height_margin = height - margin;  double proportion = 1d;//水印图片缩放比例  //int  if ((width_margin > fontWidth * proportion) && (height_margin > fontHeight * proportion))  {  }  else if ((width_margin > fontWidth * proportion) && (height_margin < fontHeight * proportion))  {  proportion = Convert.ToDouble(height_margin) / Convert.ToDouble(fontHeight);  }  else if ((width_margin < fontWidth * proportion) && (height_margin > fontHeight * proportion))  {  proportion = Convert.ToDouble(width_margin) / Convert.ToDouble(fontWidth);  }  else  {  double proportionH = Convert.ToDouble(height_margin) / Convert.ToDouble(fontHeight);  double proportionW = Convert.ToDouble(width_margin) / Convert.ToDouble(fontWidth);  proportion = proportionW >= proportionH ? proportionH : proportionW;  }  fontWidth = Convert.ToInt32(fontWidth * proportion);  fontHeight = Convert.ToInt32(fontHeight * proportion);  switch (positionConfig)  {  case "top-left":  xpos = margin;  ypos = margin;  break;  case "top-right":  xpos = width_margin - fontWidth;  ypos = margin;  break;  case "bottom-left":  xpos = margin;  ypos = height_margin - fontHeight;  break;  case "bottom-right":  xpos = width_margin - fontWidth;  ypos = height_margin - fontHeight;  break;  default:  xpos = width_margin - fontWidth;  ypos = height_margin - fontHeight;  break;  }  return new Point(xpos, ypos);  }  }  }  。

3.配置文件的WaterMarkConfig.xml，内容如下：  。

复制代码代码如下

<?xml version="1.0" encoding="utf-8" ?>  <watermark>  <allowhost>localhost:6219</allowhost><!--允许访问的域名-->  <isflag>true</isflag><!-- true、false-->  <type>font</type><!-- img、font-->  <files>/config|/upfiles/ab</files><!--需要加水印的文件夹-->  <position>bottom-right</position><!-- top-left、top-right、bottom-left、bottom-right-->  <img-path>~/UpFiles/Watermark.png</img-path><!-- 水印位置 -->  <font-style>1</font-style><!--普通文本 0, 加粗文本 1, 倾斜文本 2, 带下划线的文本 4, 中间有直线通过的文本 8-->  <font-size>60</font-size>  <font-color>red</font-color>  <font-content>￥：8000元</font-content>  <errimgpath>images/error.jpg</errimgpath><!-- 盗图片的请求返回的跟目录下的某图片 -->  </watermark>  。

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