添加水印（适用于保存图片到文件夹）

水印添加方法
using System;using System.Web;using System.Drawing.Imaging;using System.IO;using System.Drawing;/// <summary>/// 映射文件后缀名方式的数字水印/// </summary>public class CoverHandler : IHttpHandler{ public CoverHandler() { } //水印图片 private const string WATERMAEK_URL = "~/Images/WaterMark.jpg"; //默认图片 private const string DEFAULTIMAGE_URL = "~/Images/default.jpg"; public void ProcessRequest(HttpContext context) { //定义原图 System.Drawing.Image Cover; if (File.Exists(context.Request.PhysicalPath)) { //获取原图 Cover = Image.FromFile(context.Request.PhysicalPath); //获取水印图 Image watermark = Image.FromFile(context.Server.MapPath(WATERMAEK_URL)); //从指定的图创建一张画面 Graphics g = Graphics.FromImage(Cover); //在Cover上绘制水印 g.DrawImage(watermark, new Rectangle(Cover.Width - watermark.Width, Cover.Height - watermark.Height, 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(); } public bool IsReusable { get { return false; } }}