图片防盗链及添加水印

一、图片防盗链

创建web窗体
新建TestHandler 继承IHttpHandler并实现接口

public class TestHandler : IHttpHandler
    {
        public bool IsReusable
            {
            get { return true; }
            }

        public void ProcessRequest(HttpContext context)
        {
            //获取上次请求的URL
            Uri lastUrl = context.Request.UrlReferrer;
            //获取本次的请求的URL
            Uri currUrl = context.Request.Url;
            //判断是否为盗链
            if (lastUrl.Host !=currUrl.Host|| lastUrl.Port !=currUrl.Port)
            {
                //获取“请勿盗链” 警告提示图片路径
                string errorlmagePath = context.Request.PhysicalApplicationPath + "Images/4.jpg";
                context.Response.WriteFile(errorlmagePath);
            }
            else
            {
                context.Response.WriteFile(context.Request.PhysicalPath);
            }
        }
    }

新建文件夹并添加图片
添加完成后，在web.config里添加代码

    <system.webServer>
        <handlers>
            <add verb="*" path="Images/*.jpg" type="_5._3.TestHandler" name="plink" />
        </handlers>
    </system.webServer>

添加web窗体并放入图片

    <form id="form1" runat="server">
        <div>
            <img class="one" src="Images/1.jpg" />
            <img class="two" src="Images/2.jpg" />
            <img class="three" src="Images/3.jpg" />
        </div>
    </form>

最后添加新的web项目并新建web窗体

    <form id="form1" runat="server">
        <div>
            <p>以下图片来自于第一网站</p>
            <img class="one" src="https://localhost:44302/Images/1.jpg" />
            <img class="two" src="https://localhost:44302/Images/2.jpg" />
            <img class="three" src="https://localhost:44302/Images/Images/3.jpg" />
        </div>
    </form>

二、图片添加水印

创建web项目并新建图片文件夹
添加web窗体放入图片

   <form id="form1" runat="server">
       <div>
           <img src="Images/1.jpg" />
           <img src="Images/2.jpg" />
           <img src="Images/3.jpg" />
       </div>
   </form>

添加TestHandler类

    public class TestHandler : IHttpHandler
    {
        //水印图片
        private const string WATERMARK_URL = "~/Images/watermark.png";
        //图片不存在，默认显示图片
        private const string DEFAULTIMAGE_URL = "~/Images/1.jpg";

        public bool IsReusable
        {
            get { return false; }
        }

        public void ProcessRequest(HttpContext context)
        {
            //得到用户请求的图片
            string filePath = context.Request.PhysicalPath;
            System.Drawing.Image Cover;
            //判断请求的路径是否存在文件
            if (File.Exists(filePath))
            {
                Cover = Image.FromFile(filePath);
                Image wateremark = Image.FromFile(context.Server.MapPath(WATERMARK_URL));
                Graphics g = Graphics.FromImage(Cover);
                g.DrawImage(wateremark, new Rectangle(Cover.Width - wateremark.Width,
                    Cover.Height - wateremark.Height, wateremark.Width, wateremark.Height), 0,
                    0, wateremark.Width, wateremark.Height, GraphicsUnit.Pixel);
                g.Dispose();
                wateremark.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();
        }

最后在web.config中插入代码

<handlers>
      <add verb="*" path="Images/*.jpg" name="handler" type="_5._4.TestHandler"/>
</handlers>