ASP.NET 图片加水印防盗链

首先建一个类：

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：

<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

?

<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：

?

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

                    stringsImgStartPhysicalPath = 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();

 

                    }

                    elseif (drConfing["type"].Equals("font"))

                    {

                        //文字水印

                        stringcontent = drConfing["font-content"].ToString();

                        floatSize = (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,intwidth,int height,intwatermarkWidth,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, intheight, 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：

?

<?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>