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