/// summary>
/// 缩略图
/// /summary>
public class Thumbnail
{
  public Thumbnail(string id, byte[] data)
  {
    this.ID = id;
    this.Data = data;
  }

  private string id;

  /// summary>
  /// 图片id
  /// /summary>
  public string ID
  {
    get
    {
      return this.id;
    }
    set
    {
      this.id = value;
    }
  }

  private byte[] thumbnail_data;

  /// summary>
  /// 图片的二进制数据
  /// /summary>
  public byte[] Data
  {
    get
    {
      return this.thumbnail_data;
    }
    set
    {
      this.thumbnail_data = value;
    }
  }

  private string contentType;

  /// summary>
  /// 图片对应的MIME类型
  /// /summary>
  public string ContentType
  {
    get
    {
      return contentType;
    }

    set
    {
      contentType = value;
    }
  }
}

!DOCTYPE html>

html xmlns="http://www.w3.org/1999/xhtml">
head>
  title>Upload Images/title>
  script src="swfupload/swfupload.js">/script>
  script src="swfupload/handlers.js">/script>
  script>
    //注：div的id名称最好不要改，要改的话在handlers.js文件中也要进行修改，div的名称已经在handlers.js文件中写死
    var swfu;
    window.onload = function () {
      swfu = new SWFUpload({
        // 后台设置，设置处理上传的页面
        upload_url: "/Handlers/ImageUploadHandler.ashx",
        // 文件上传大小限制设置
        file_size_limit: "3 MB",
        //文件类型设置，多种格式以英文中的分号分开
        file_types: "*.jpg;*.png",
        //文件描述，与弹出的选择文件对话框相关
        file_types_description : "Images file",
        //设置上传文件数量限制
        file_upload_limit: "1",

        //事件处理程序，最好不要改，事件处理程序已在handlers.js文件中定义
        // Event Handler Settings - these functions as defined in Handlers.js
        // The handlers are not part of SWFUpload but are part of my website and control how
        // my website reacts to the SWFUpload events.
        file_queue_error_handler : fileQueueError,
        file_dialog_complete_handler : fileDialogComplete,
        upload_progress_handler : uploadProgress,
        upload_error_handler : uploadError,
        upload_success_handler : uploadSuccess,
        upload_complete_handler : uploadComplete,

        // 上传按钮设置
        button_image_url : "/swfupload/images/XPButtonNoText_160x22.png",
        button_placeholder_id: "spanButtonPlaceholder",
        button_width: 160,
        button_height: 22,
        button_text : '请选择图片 (最大3M)',
        button_text_style : '.button { font-family: Helvetica, Arial, sans-serif; font-size: 14pt; } .buttonSmall { font-size: 10pt; }',
        button_text_top_padding: 1,
        button_text_left_padding: 5,

        // swfupload.swf flash设置
        flash_url : "/swfupload/swfupload.swf",  
        //自定义的其他设置
        custom_settings : {
          upload_target: "divFileProgressContainer"
        },
        // 是否开启调试模式，调试时可以设置为true，发布时设置为false
        debug: false
      });
    }
  /script>
/head>
body>
  form id="form1">
    div id="content">
        h2>Upload Images Demo/h2>
    
    div id="swfu_container" style="margin: 0px 10px;">
      div>
        span id="spanButtonPlaceholder">/span>
      /div>
      div id="divFileProgressContainer" style="height: 75px;">/div>
      div id="thumbnails">/div>
    /div>
    /div>
  /form>
/body>
/html>

/// summary>
  /// 图片上传处理
  /// /summary>
  public class ImageUploadHandler : IHttpHandler, IRequiresSessionState
  {
    /// summary>
    /// 记录日志 logger
    /// /summary>
    private static Common.LogHelper logger = new Common.LogHelper(typeof(ImageUploadHandler));
    public void ProcessRequest(HttpContext context)
    {
      context.Response.ContentType = "text/plain";
      System.Drawing.Image thumbnail_image = null;
      System.Drawing.Image original_image = null;
      System.Drawing.Bitmap final_image = null;
      System.Drawing.Graphics graphic = null;
      MemoryStream ms = null;
      try
      {
        //验证用户是否登录，是否有权限上传
        if (context.Session["User"]==null)
        {
          context.Response.Write("没有上传图片的权限！");
          context.Response.End();
          return;
        }
        //获取上传文件
        HttpPostedFile image_upload = context.Request.Files["Filedata"];
        //获取文件扩展名
        string fileExt = System.IO.Path.GetExtension(image_upload.FileName).ToLower();
        //验证文件扩展名是否符合要求，是否是允许的图片格式
        if (fileExt!=".jpg"fileExt!=".png")
        {
          return;
        }
        //当前时间字符串
        string timeString = DateTime.Now.ToString("yyyyMMddHHmmssfff");
        //图片保存虚拟路径构建
        string path = "/Upload/"+timeString + fileExt;
        //保存到Session 变量中
        context.Session["imgPath"] = path;
        //获取、构建要上传文件的物理路径
        string serverPath = context.Server.MapPath("~/"+path);
        //保存图片到服务器
        image_upload.SaveAs(serverPath);
        //记录日志
        logger.Debug("图片上传成功！");
        #region 生成缩略图

        // 获取上传图片的文件流
        original_image = System.Drawing.Image.FromStream(image_upload.InputStream);

        // 根据原图计算缩略图的宽度和高度，及缩放比例等~~
        int width = original_image.Width;
        int height = original_image.Height;
        int target_width = 100;
        int target_height = 100;
        int new_width, new_height;

        float target_ratio = (float)target_width / (float)target_height;
        float image_ratio = (float)width / (float)height;

        if (target_ratio > image_ratio)
        {
          new_height = target_height;
          new_width = (int)Math.Floor(image_ratio * (float)target_height);
        }
        else
        {
          new_height = (int)Math.Floor((float)target_width / image_ratio);
          new_width = target_width;
        }

        new_width = new_width > target_width ? target_width : new_width;
        new_height = new_height > target_height ? target_height : new_height;

        //创建缩略图
        final_image = new System.Drawing.Bitmap(target_width, target_height);
        graphic = System.Drawing.Graphics.FromImage(final_image);
        graphic.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, target_width, target_height));
        int paste_x = (target_width - new_width) / 2;
        int paste_y = (target_height - new_height) / 2;
        graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; /* new way */
                                                      //graphic.DrawImage(thumbnail_image, paste_x, paste_y, new_width, new_height);
        graphic.DrawImage(original_image, paste_x, paste_y, new_width, new_height);

        // Store the thumbnail in the session (Note: this is bad, it will take a lot of memory, but this is just a demo)
        ms = new MemoryStream();
        //将缩略图保存到内存流中
        final_image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

        #endregion

        //建立 Thumbnail对象
        Thumbnail thumb = new Thumbnail(timeString, ms.GetBuffer());
        //保存缩略图到Session 中，也可以保存成文件，保存为图片
        context.Session["file_info"] = thumb;
        //操作成功，返回HTTP状态码设置为 200
        context.Response.StatusCode = 200;
        //输出缩略图的id，在生成缩略图时要用到
        context.Response.Write(thumb.ID);
      }
      catch(Exception ex)
      {
        // 出现异常，返回 500，服务器内部错误
        context.Response.StatusCode = 500;
        //记录错误日志
        logger.Error(ex);
      }
      finally
      {
        // 释放资源
        if (final_image != null) final_image.Dispose();
        if (graphic != null) graphic.Dispose();
        if (original_image != null) original_image.Dispose();
        if (thumbnail_image != null) thumbnail_image.Dispose();
        if (ms != null) ms.Close();
        context.Response.End();
      }
    }

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

/// summary>
  /// 获取缩略图
  /// /summary>
  public class GetThumbHandler : IHttpHandler, IRequiresSessionState
  {
    public void ProcessRequest(HttpContext context)
    {
      context.Response.ContentType = "text/plain";
      //获取缩略图id
      string id = context.Request.QueryString["id"];
      //id为空则返回错误
      if (String.IsNullOrEmpty(id))
      {
        context.Response.StatusCode = 404;
        context.Response.Write("Not Found");
        context.Response.End();
        return;
      }
      //从Session中获取缩略图文件
      Thumbnail thumb= context.Session["file_info"] as Thumbnail;
      //判断id是否一致
      if (thumb.ID == id)
      {
        //重新设置响应MIME 类型
        context.Response.ContentType = "image/png";
        //输出二进制流信息
        context.Response.BinaryWrite(thumb.Data);
        //截止输出
        context.Response.End();
        return;
      }

      //没有找到相应图片，返回404
      context.Response.StatusCode = 404;
      context.Response.Write("Not Found");
      context.Response.End();
    }

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

function fileQueueError(file, errorCode, message) {
  try {
    var imageName = "error.gif";
    var errorName = "";
    if (errorCode == SWFUpload.errorCode_QUEUE_LIMIT_EXCEEDED) {
      errorName = "上传文件过多！";
    }

    if (errorName != "") {
      alert(errorName);
      return;
    }

    switch (errorCode) {
    case SWFUpload.QUEUE_ERROR.ZERO_BYTE_FILE:
      imageName = "zerobyte.gif";
      break;
    case SWFUpload.QUEUE_ERROR.FILE_EXCEEDS_SIZE_LIMIT:
      imageName = "toobig.gif";
      break;
    case SWFUpload.QUEUE_ERROR.ZERO_BYTE_FILE:
    case SWFUpload.QUEUE_ERROR.INVALID_FILETYPE:
    default:
      alert(message);
      break;
    }
    //添加图片，注意路径
    addImage("/swfupload/images/" + imageName);

  } catch (ex) {
    this.debug(ex);
  }

}

function fileDialogComplete(numFilesSelected, numFilesQueued) {
  try {
    if (numFilesQueued > 0) {
      this.startUpload();
    }
  } catch (ex) {
    this.debug(ex);
  }
}

function uploadProgress(file, bytesLoaded) {

  try {
    var percent = Math.ceil((bytesLoaded / file.size) * 100);

    var progress = new FileProgress(file, this.customSettings.upload_target);
    progress.setProgress(percent);
    if (percent === 100) {
      progress.setStatus("正在创建缩略图...");
      progress.toggleCancel(false, this);
    } else {
      progress.setStatus("正在上传...");
      progress.toggleCancel(true, this);
    }
  } catch (ex) {
    this.debug(ex);
  }
}

function uploadSuccess(file, serverData) {
  try {
    //添加缩略图~~~
    //修改这里来设置生成缩略图的页面
    addImage("/Handlers/GetThumbHandler.ashx?id=" + serverData);
    var progress = new FileProgress(file, this.customSettings.upload_target);
    progress.setStatus("缩略图创建成功！");
    progress.toggleCancel(false);
  } catch (ex) {
    this.debug(ex);
  }
}

function uploadComplete(file) {
  try {
    /* I want the next upload to continue automatically so I'll call startUpload here */
    if (this.getStats().files_queued > 0) {
      this.startUpload();
    } else {
      var progress = new FileProgress(file, this.customSettings.upload_target);
      progress.setComplete();
      progress.setStatus("图片上传成功");
      progress.toggleCancel(false);
    }
  } catch (ex) {
    this.debug(ex);
  }
}

function uploadError(file, errorCode, message) {
  var imageName = "error.gif";
  var progress;
  try {
    switch (errorCode) {
    case SWFUpload.UPLOAD_ERROR.FILE_CANCELLED:
      try {
        progress = new FileProgress(file, this.customSettings.upload_target);
        progress.setCancelled();
        progress.setStatus("上传操作被取消");
        progress.toggleCancel(false);
      }
      catch (ex1) {
        this.debug(ex1);
      }
      break;
    case SWFUpload.UPLOAD_ERROR.UPLOAD_STOPPED:
      try {
        progress = new FileProgress(file, this.customSettings.upload_target);
        progress.setCancelled();
        progress.setStatus("上传停止！");
        progress.toggleCancel(true);
      }
      catch (ex2) {
        this.debug(ex2);
      }
    case SWFUpload.UPLOAD_ERROR.UPLOAD_LIMIT_EXCEEDED:
      imageName = "uploadlimit.gif";
      break;
    default:
      alert(message);
      break;
    }

    addImage("/swfupload/images/" + imageName);

  } catch (ex3) {
    this.debug(ex3);
  }

}

function addImage(src) {
  var newImg = document.createElement("img");
  newImg.style.margin = "5px";
  document.getElementById("thumbnails").appendChild(newImg);
  if (newImg.filters) {
    try {
      newImg.filters.item("DXImageTransform.Microsoft.Alpha").opacity = 0;
    } catch (e) {
      // If it is not set initially, the browser will throw an error. This will set it if it is not set yet.
      newImg.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(opacity=' + 0 + ')';
    }
  } else {
    newImg.style.opacity = 0;
  }

  newImg.onload = function () {
    fadeIn(newImg, 0);
  };
  newImg.src = src;
}

function fadeIn(element, opacity) {
  var reduceOpacityBy = 5;
  var rate = 30;  // 15 fps


  if (opacity  100) {
    opacity += reduceOpacityBy;
    if (opacity > 100) {
      opacity = 100;
    }

    if (element.filters) {
      try {
        element.filters.item("DXImageTransform.Microsoft.Alpha").opacity = opacity;
      } catch (e) {
        // If it is not set initially, the browser will throw an error. This will set it if it is not set yet.
        element.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(opacity=' + opacity + ')';
      }
    } else {
      element.style.opacity = opacity / 100;
    }
  }

  if (opacity  100) {
    setTimeout(function () {
      fadeIn(element, opacity);
    }, rate);
  }
}

/* ******************************************
 *  FileProgress Object
 *  Control object for displaying file info
 * ****************************************** */

function FileProgress(file, targetID) {
  this.fileProgressID = "divFileProgress";

  this.fileProgressWrapper = document.getElementById(this.fileProgressID);
  if (!this.fileProgressWrapper) {
    this.fileProgressWrapper = document.createElement("div");
    this.fileProgressWrapper.className = "progressWrapper";
    this.fileProgressWrapper.id = this.fileProgressID;

    this.fileProgressElement = document.createElement("div");
    this.fileProgressElement.className = "progressContainer";

    var progressCancel = document.createElement("a");
    progressCancel.className = "progressCancel";
    progressCancel.href = "#";
    progressCancel.style.visibility = "hidden";
    progressCancel.appendChild(document.createTextNode(" "));

    var progressText = document.createElement("div");
    progressText.className = "progressName";
    progressText.appendChild(document.createTextNode(file.name));

    var progressBar = document.createElement("div");
    progressBar.className = "progressBarInProgress";

    var progressStatus = document.createElement("div");
    progressStatus.className = "progressBarStatus";
    progressStatus.innerHTML = "nbsp;";

    this.fileProgressElement.appendChild(progressCancel);
    this.fileProgressElement.appendChild(progressText);
    this.fileProgressElement.appendChild(progressStatus);
    this.fileProgressElement.appendChild(progressBar);

    this.fileProgressWrapper.appendChild(this.fileProgressElement);

    document.getElementById(targetID).appendChild(this.fileProgressWrapper);
    fadeIn(this.fileProgressWrapper, 0);

  } else {
    this.fileProgressElement = this.fileProgressWrapper.firstChild;
    this.fileProgressElement.childNodes[1].firstChild.nodeValue = file.name;
  }

  this.height = this.fileProgressWrapper.offsetHeight;

}
FileProgress.prototype.setProgress = function (percentage) {
  this.fileProgressElement.className = "progressContainer green";
  this.fileProgressElement.childNodes[3].className = "progressBarInProgress";
  this.fileProgressElement.childNodes[3].style.width = percentage + "%";
};
FileProgress.prototype.setComplete = function () {
  this.fileProgressElement.className = "progressContainer blue";
  this.fileProgressElement.childNodes[3].className = "progressBarComplete";
  this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setError = function () {
  this.fileProgressElement.className = "progressContainer red";
  this.fileProgressElement.childNodes[3].className = "progressBarError";
  this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setCancelled = function () {
  this.fileProgressElement.className = "progressContainer";
  this.fileProgressElement.childNodes[3].className = "progressBarError";
  this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setStatus = function (status) {
  this.fileProgressElement.childNodes[2].innerHTML = status;
};
FileProgress.prototype.toggleCancel = function (show, swfuploadInstance) {
  this.fileProgressElement.childNodes[0].style.visibility = show ? "visible" : "hidden";
  if (swfuploadInstance) {
    var fileID = this.fileProgressID;
    this.fileProgressElement.childNodes[0].onclick = function () {
      swfuploadInstance.cancelUpload(fileID);
      return false;
    };
  }
};