asp.net继承IHttpHandler接口实现给网站图片添加水印功能实例

public class ImageSY : IHttpHandler
{
 public ImageSY()
 {
 //
 //TODO: 在此处添加构造函数逻辑
 //
 }
 #region IHttpHandler 成员
 public bool IsReusable
 {
 get { return true; }
 }
 public void ProcessRequest(HttpContext context)
 {
 //获得请求的物理图片路径
 string imagePath = context.Request.PhysicalPath;
 System.Drawing.Image image = null;
 if (File.Exists(imagePath))
 {
 //定义水印文字
 string text = "本图片来至我的网站";
 //定义水印文字字体大小
 int fontSize = 22;
 //水印文字字体
 Font font = new Font("宋体", fontSize);
 //根据图片物理地址加载图片
 image = System.Drawing.Image.FromFile(imagePath);
 Graphics g = Graphics.FromImage(image);
 //获取要绘制水印文字所需要的显示区域大小
 SizeF size = g.MeasureString(text, font);
 if (size.Width > image.Width || size.Height > image.Height)
 {
 }
 else
 {
 Brush brush = Brushes.Red;
 g.DrawString(text, font, brush, image.Width - size.Width, image.Height - size.Height);
 g.Dispose();
 }
 }
 else
 {
 }
 image.Save(context.Response.OutputStream, ImageFormat.Jpeg);
 }
 #endregion
}

<location path="images">
 <system.web>
 <httpHandlers>
 <!---对jpg文件添加水印-->
 <add verb="*" type="ImageSY" path="*.jpg"/>
 <add verb="*" type="ImageSY" path="*.gif"/>
 <add verb="*" type="ImageSY" path="*.bmp"/>
 </httpHandlers>
 </system.web>
 </location>