ASP.NET MVC中使用uploadify上传图片并按照规定大小压缩图片

 $(document).ready(function () {         
            $('#uploadify').uploadify({
                onUploadSuccess: function (file, returndata, response) {
                    var data = eval('(' + returndata + ')');
                    if (response == true && data.Success == 'true') {
                        $("input[name=BACKIMG]").attr("value", data.FileName);//data.FileName为图片保存路径
                        $('#mainForm').submit();
                    } else {
                        alert(data.Message);
                    }
                },
                'height': 20,
                'width': 35,
                'uploadLimit': 1,
                'queueSizeLimit': 1,
                'queueID': 'fileQueue',              
                'removeCompleted': false,
                'auto': false,
                'multi': false,
                'buttonText': '浏览图片',
                'swf': '@Url.Content("~/Scripts/uploadify/uploadify.swf")',
                'uploader': '@Url.Content("~/Scripts/uploadify/UploadAttach.ashx")'
            });

将图片上传到服务器的方法为UploadAttach.ashx

 /// <summary>
    /// UploadAttach 的摘要说明
    /// </summary>
    public class UploadAttach : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            HttpPostedFile fileData = context.Request.Files["fileData"];
            string floder = context.Request["floder"];
            if (fileData != null)
            {
                try
                {
                    // 文件上传后的保存路径
                    string path = "~/img/";                  
                    string filePath = context.Server.MapPath(path);
                    if (!Directory.Exists(filePath))
                    {
                        Directory.CreateDirectory(filePath);
                    }
                    string saveFileName = Guid.NewGuid().ToString() + fileData.FileName;
                
                    string newFilePath = filePath + saveFileName;
                    fileData.SaveAs(newFilePath);

                    //图片裁切
                    var thumbFilePath = newFilePath.Replace(Path.GetExtension(newFilePath),
                                                            ".thumb" + Path.GetExtension(newFilePath));
                    ImageKit.MakeCenterThumbnail(newFilePath, thumbFilePath, 1602, 400);
                    if (File.Exists(newFilePath))
                    {
                        File.Delete(newFilePath);
                    }
                    context.Response.Write("{'Success':'true','FileName':'" + saveFileName.Replace(".", ".thumb.") + "'}");
                }
                catch (Exception ex)
                {
                    context.Response.Write("{'Success':'false','Message':'"+ex.Message+"'}");
                }
            }
            else
            {
                context.Response.Write("{'Success':'false','Message':'请选择要上传的文件'}");
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

图片裁剪压缩的方法

 public static class ImageKit
    {
          public static bool MakeCenterThumbnail(string origPath, string destPath, int width, int height)
        {
            try
            {
                using (Image image = Image.FromFile(origPath))
                {
                    int originalWidth = image.Width;
                    int originalHeight = image.Height;
                    double ratio = Math.Max((originalWidth / (double)width < originalHeight / (double)height)
                                        ? originalWidth / (double)width
                                        : originalHeight / (double)height, 1);

                    var cutSize = new Size((int)Math.Round(width * ratio, 0), (int)Math.Round(height * ratio, 0));

                    int x = (int)Math.Round((double)(originalWidth - cutSize.Width) / 2, 0);
                    int y = (int)Math.Round((double)(originalHeight - cutSize.Height) / 2, 0); ;

                    var bitmap = new Bitmap(width, height);
                    using (var graphics = Graphics.FromImage(bitmap))
                    {
                        graphics.CompositingQuality = CompositingQuality.HighQuality;
                        graphics.SmoothingMode = SmoothingMode.HighQuality;
                        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        graphics.Clear(Color.White);

                        var destRect = new Rectangle(0, 0, width, height);
                        var originalRect = new Rectangle(x, y, cutSize.Width, cutSize.Height);
                        graphics.DrawImage(image, destRect, originalRect, GraphicsUnit.Pixel);
                    }
                    #region wjy20131004修改
                    // 以下代码为保存图片时,设置压缩质量
                    EncoderParameters encoderParams = new EncoderParameters();
                    long[] quality = new long[1];
                    quality[0] = 100;
                    EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
                    encoderParams.Param[0] = encoderParam;
                    //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象.
                    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                    ImageCodecInfo jpegICI = null;
                    for (int i = 0;i < arrayICI.Length;i++)
                    {
                        if (arrayICI[i].FormatDescription.Equals("JPEG"))
                        {
                            jpegICI = arrayICI[i];
                            //设置JPEG编码
                            break;
                        }
                    }
                    if (jpegICI != null)
                    {
                        bitmap.Save(destPath, jpegICI, encoderParams);
                    }

                    //bitmap.Save(destPath);
                    #endregion
                }
                return true;
            }
            catch
            {
                return false;
            }
        }
    }

使用方法：

1，首先要添加JS引用

<script src="../../Scripts/uploadify/v3.1/jquery.uploadify-3.1.min.js" type="text/javascript"></script>
<link href="../../Scripts/uploadify/v3.1/uploadify1.css" rel="stylesheet" type="text/css" />

2，在页面中显示上传附件的按钮：

<div id="fileQueue">
</div>
<input type="file" name="uploadify" id="uploadify" />
<input type="hidden" name="BACKIMG" value=""/>

注意：隐藏控件BACKIMG是上传文件的路径，文件上传成功后要给它赋值，这样在表单提交成功后才可以根据图片路径读取到上传图片

3，如下所示Form表单   

<form id="mainForm" method="post" action='@Url.Action(Model.Action)'> </form>

  提交时调用上传图片的方法

 function submitbut() {
            var filecount = $('#fileQueue').find('div').length;
            if (filecount > 0) {
                $('#uploadify').uploadify('upload', '*');
            } else {
                $('#mainForm').submit();
            }
        }