使用ajaxfileupload.js插件

html代码：

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 2     ajax上传 3      4      5    
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文件上传后台处理代码（asp.net版）

1 <%@ webhandler Language="C#" class="Upload" %> 2  3 using System; 4 using System.Collections; 5 using System.Web; 6 using System.IO; 7 using System.Globalization; 8 using LitJson; 9 public class Upload : IHttpHandler10 {11  private HttpContext context;12  public void ProcessRequest(HttpContext context)13  {14   String aspxUrl = context.Request.Path.Substring(0, context.Request.Path.LastIndexOf("/") + 1);15  16   //文件保存目录路径17   String savePath = "attached/";18   //文件保存目录URL19   String saveUrl = aspxUrl + "attached/";20   //定义允许上传的文件扩展名21   Hashtable extTable = new Hashtable();22   extTable.Add("image", "gif,jpg,jpeg,png,bmp");23   extTable.Add("flash", "swf,flv");24   extTable.Add("media", "swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb");25   extTable.Add("file", "doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2");26   //最大文件大小27   int maxSize = 1000000;28   this.context = context;29   HttpPostedFile imgFile = context.Request.Files["imgFile"];30   if (imgFile == null)31   {32    showError("请选择文件。");33   }34   String dirPath = context.Server.MapPath(savePath);35   if (!Directory.Exists(dirPath))36   {37    showError("上传目录不存在。");38   }39   String dirName = context.Request.QueryString["dir"];40   if (String.IsNullOrEmpty(dirName)) {41    dirName = "image";42   }43   if (!extTable.ContainsKey(dirName)) {44    showError("目录名不正确。");45   }46   String fileName = imgFile.FileName;47   String fileExt = Path.GetExtension(fileName).ToLower();48   if (imgFile.InputStream == null || imgFile.InputStream.Length > maxSize)49   {50    showError("上传文件大小超过限制。");51   }52   if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(((String)extTable[dirName]).Split(','), fileExt.Substring(1).ToLower()) == -1)53   {54    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。");55   }56   //创建文件夹57   dirPath += dirName + "/";58   saveUrl += dirName + "/";59   if (!Directory.Exists(dirPath)) {60    Directory.CreateDirectory(dirPath);61   }62   String ymd = DateTime.Now.ToString("yyyyMMdd", DateTimeFormatInfo.InvariantInfo);63   dirPath += ymd + "/";64   saveUrl += ymd + "/";65   if (!Directory.Exists(dirPath)) {66    Directory.CreateDirectory(dirPath);67   }68   String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", DateTimeFormatInfo.InvariantInfo) + fileExt;69   String filePath = dirPath + newFileName;70   imgFile.SaveAs(filePath);71   String fileUrl = saveUrl + newFileName;72   Hashtable hash = new Hashtable();73   hash["error"] = 0;74   hash["url"] = fileUrl;75   context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8");76   context.Response.Write(JsonMapper.ToJson(hash));77   context.Response.End();78  }79  private void showError(string message)80  {81   Hashtable hash = new Hashtable();82   hash["error"] = 1;83   hash["message"] = message;84   context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8");85   context.Response.Write(JsonMapper.ToJson(hash));86   context.Response.End();87  }88  public bool IsReusable89  {90   get91   {92    return true;93   }94  }95 }