asp.net如何给每张图片动态添加水印方法（二）

第一步，在App_Code中新建一个类，类名为BookCoverHandler，然后代码如下

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Drawing;

using System.Drawing.Imaging;

using System.IO;

/// <summary>

///BookCoverHandler 的摘要说明

/// </summary>

public class BookCoverHandler:IHttpHandler

{

    public void ProcessRequest(HttpContext context)

    {

        //获取请求的图片信息

        //string isbn = context.Request.QueryString["isbn"];

        //找图片

        //string path = context.Server.MapPath("~/Images/BookCovers/" + isbn + ".jpg");

        string path = context.Request.PhysicalPath;

        string defaultPath = context.Server.MapPath("~/images/default.jpg");

        string waterPath = context.Server.MapPath("~/images/watermark.jpg");

        //处理图片

        Image cover;

        //图片存在加水印

        if (File.Exists(path))

        {

            Image water = Image.FromFile(waterPath);

            cover = Image.FromFile(path);

            Graphics g = Graphics.FromImage(cover);

            g.DrawImage(water,

                cover.Width - water.Width,

                cover.Height - water.Height,

                water.Width,

                water.Height);

            g.Dispose();

        }

        else//图片不存在加载默认图片 

        {

            cover = Image.FromFile(defaultPath);

        }

        context.Response.ContentType = "image/jpeg";

        cover.Save(context.Response.OutputStream, ImageFormat.Jpeg);

        cover.Dispose();

        context.Response.End();

    }

    public bool IsReusable

    {

        get

        {

            return true;

        }

    }

}

第二部，在web.config中

    <httpHandlers>

      <!--图片水印-->

      <add verb="*" type="BookCoverHandler" path="Images/BookCovers/*.jpg" />

    </httpHandlers>

然后就会为Images/BookCovers/下的jpg图片自动添加水印