自己动手打造ajax图片上传

 <p>
    <label>ajax上传</label>
    <input type="file" name="fileToUpload" id="fileToUpload" class="inp_fileToUpload" multiple="multiple"/>
    <img src="$web.site$web.tpl#**#adminht/images/lb_head.jpg" width="30px" height="30px" class="img_upload" id="img" />
   </p>
   <p>
    <label>最新修改人员：</label>
    <input readonly="readonly" type="text" size="30" />
   </p>
   <div>
   
    <script type="text/javascript">
     $(function() {
      $(".inp_fileToUpload").live("change", function() {//现在这个已经适用于多个file表单。
       ajaxFileUpload($(this).attr("id"), $(this).parent().children(".img_upload").attr("id"));
      })
     })
     function ajaxFileUpload(file_id, img_id) {
      jQuery.ajaxFileUpload({
       url : '/upload/upload_json.ashx', //用于文件上传的服务器端请求地址
       secureuri : false, //是否需要安全协议，一般设置为false
       fileElementId : file_id, //文件上传域的ID
       dataType : 'json', //返回值类型 一般设置为json
       success : function(data, status)//服务器成功响应处理函数
       {
        if (data.error == 0) {
         $("#" + img_id).attr("src", data.url);
        } else {
         alert(data.message);
        }
       },
       error : function(data, status, e)//服务器响应失败处理函数
       {
        alert(e);
       }
      })
      return false;
     }
    </script>
   </div>
  </div>

<%@ webhandler Language="C#" class="Upload" %>

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)
 {
  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 = 1000000;
  this.context = context;
  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。");
  }
  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);
  }
  String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", DateTimeFormatInfo.InvariantInfo) + fileExt;
  String filePath = dirPath + newFileName;
  imgFile.SaveAs(filePath);
  String fileUrl = saveUrl + newFileName;
  Hashtable hash = new Hashtable();
  hash["error"] = 0;
  hash["url"] = fileUrl;
  context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8");
  context.Response.Write(JsonMapper.ToJson(hash));
  context.Response.End();
 }
 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;
  }
 }
}