asp.net中使kindeditor自动生成缩略图

using System;
using System.Collections;
using System.Web;
using System.IO;
using System.Globalization;
using LitJson;

public class Upload : IHttpHandler
{
    private HttpContext context;

    public void ProcessRequest(HttpContext context)
    {
        //获得文件名
        String aspxUrl = context.Request.Path.Substring(0, context.Request.Path.LastIndexOf("/") + 1);
        //文件保存目录路径
        String savePath = "../attached/";
        //文件保存目录URL
        String saveUrl = aspxUrl + "../attached/";
        //定义允许上传的文件扩展名
        Hashtable extTable = new Hashtable();
        extTable.Add("image", "gif,jpg,jpeg,png,bmp");
        extTable.Add("flash", "swf,flv");
        extTable.Add("media", "swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb");
        extTable.Add("file", "doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2");

        //最大文件大小
        int maxSize = 52428800;
        this.context = context;
        //获取文件
        HttpPostedFile imgFile = context.Request.Files["imgFile"];
        if (imgFile == null)
        {
            showError("请选择文件。");
        }

        String dirPath = context.Server.MapPath(savePath);
        if (!Directory.Exists(dirPath))
        {
            showError("上传目录不存在。");
        }
        //获取文件类型
        String dirName = context.Request.QueryString["dir"];
        if (String.IsNullOrEmpty(dirName)) {
            dirName = "image";
        }
      
        if (!extTable.ContainsKey(dirName)) {
            showError("目录名不正确。");
        }

        String fileName = imgFile.FileName;
        String fileExt = Path.GetExtension(fileName).ToLower();

        if (imgFile.InputStream == null || imgFile.InputStream.Length > maxSize)
        {
            showError("上传文件大小超过限制。");
        }

        if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(((String)extTable[dirName]).Split(‘,‘), fileExt.Substring(1).ToLower()) == -1)
        {
            showError("上传文件扩展名是不允许的扩展名。n只允许" + ((String)extTable[dirName]) + "格式。");
        }

        //创建文件夹
        dirPath += dirName + "/";
        saveUrl += dirName + "/";
        if (!Directory.Exists(dirPath)) {
            Directory.CreateDirectory(dirPath);
        }
        String ymd = DateTime.Now.ToString("yyyyMMdd", DateTimeFormatInfo.InvariantInfo);
        dirPath += ymd + "/";
        saveUrl += ymd + "/";
        if (!Directory.Exists(dirPath)) {
            Directory.CreateDirectory(dirPath);
        }
        //生成文件名
        String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", DateTimeFormatInfo.InvariantInfo) + fileExt;
        //文件保存的物理里地址
        String filePath = dirPath + newFileName;
        //保存文件
        imgFile.SaveAs(filePath);
        //文件相对地址
        String fileUrl = saveUrl + newFileName;
        //设置返回信息，返回值是以JSON数组形式返回的，即前面是key,后面是value
        Hashtable hash = new Hashtable();
        hash["error"] = 0;
        //返回原图的地址
        hash["url"] = fileUrl;
        /*
         还可设置多个返回结果,比如图片的宽，高等
         如：hash["width"]=100;
         */
        //判断上传的文件类型
        if (context.Request.QueryString["dir"] == "image")
        {
            //请求中有width这个参数表示图片需要进行处理
            if (context.Request.QueryString["width"] != null)
            {   //缩略图相对地址
                string thumbfilePath = dirPath + "Thumb" + newFileName;
                int width=Convert.ToInt32(context.Request.QueryString["width"]);
                int height=Convert.ToInt32(context.Request.QueryString["height"]);
                //获得原始图片的宽和高
                System.Drawing.Image originalImage = System.Drawing.Image.FromFile(filePath);
                int ow = originalImage.Width;
                int oh = originalImage.Height;
                //如果原图的尺寸比缩略图要求的尺寸小,则不进行任何处理
                if (width <= ow && height <= oh)
                {
                    string smillUrl = fileUrl;
                    //返回缩略图的地址
                    hash["thumUrl"] = smillUrl;
                }
                else
                {
                    //生成缩略图
                    if (MakeThumbnail(filePath, thumbfilePath, width, height, "HW"))
                    {
                        string smillUrl = saveUrl + "Thumb" + newFileName;
                        hash["thumUrl"] = smillUrl;
                    }
                    else
                    {
                        showError("生成缩略图失败");
                    }
                }
            }
        }
        context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8");
        context.Response.Write(JsonMapper.ToJson(hash));
        context.Response.End();
    }
    //返回错误消息
    private void showError(string message)
    {
        Hashtable hash = new Hashtable();
        hash["error"] = 1;
        hash["message"] = message;
        context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8");
        context.Response.Write(JsonMapper.ToJson(hash));
        context.Response.End();
    }

    public bool IsReusable
    {
        get
        {
            return true;
        }
    }
    /// <summary>
    /// 生成缩略图
    /// </summary>
    /// <param name="originalImagePath">源图路径（物理路径）</param>
    /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
    /// <param name="width">缩略图宽度</param>
    /// <param name="height">缩略图高度</param>
    /// <param name="mode">生成缩略图的方式</param>
    public static bool MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
    {
        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
        int towidth = width;
        int toheight = height;
        int x = 0;
        int y = 0;
        int ow = originalImage.Width;
        int oh = originalImage.Height;
            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形）               
                    break;
                case "W"://指定宽，高按比例                   
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形）               
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
                new System.Drawing.Rectangle(x, y, ow, oh),
                System.Drawing.GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                return true;
            }
            catch (System.Exception e)
            {
                return false;
                throw e;

            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
    }
}

前台调用就很简单了，这里也贴一下：

KindEditor.ready(function (K) {
    var uploadbutton = K.uploadbutton({
        button: K(‘#uploadButton‘)[0],
        //上传的文件类型
        fieldName: ‘imgFile‘,
        //注意后面的参数，dir表示文件类型，width表示缩略图的宽，height表示高
        url: ‘../Editer/asp.net/upload_json.ashx?dir=image&width=65&height=61‘,
        afterUpload: function (data) {
            if (data.error === 0) {
                alert(‘图片上传成功‘);
                //取返回值,注意后台设置的key,如果要取原值
                //取缩略图地址
                var thumUrl = K.formatUrl(data.thumUrl, ‘absolute‘);
                //取原图地址
                //var url=k.fromUrl(data.Url,‘absolute‘);
                K(‘#txtPic‘).val(thumUrl);
            } else {
                alert(data.message);
            }
        },
        afterError: function (str) {
            alert(‘自定义错误信息: ‘ + str);
        }
    });
    uploadbutton.fileBox.change(function (e) {
        uploadbutton.submit();
    });
});