文件上传ajaxfileupload.js插件

Html:

 <div class="container">
        <form id="form" runat="server" method="post" enctype="multipart/form-data" action="Upfile.ashx">
        <span class="input-file" id="Filetransfer">
            <img src="data:images/Filetransfer.png" style="z-index: -1; width: 100%; height: 100%;" />
            <input class="fileInput" type="file" name="file1" id="file1" onchange="submitform()" />
        </span>
        </form>
    </div>
script:

  <script type="text/javascript" src="js/jquery-1.8.3.min.js"></script>
    <script src="js/ajaxfileupload.js" type="text/javascript"></script>

 <script type="text/javascript">
        function submitform() {
            if ($("#file1").val().length > 0) {
                ajaxFileUpload();
            }
            else {
                alert("请选择图片");
            }
        }

        function ajaxFileUpload() {
            $.ajaxFileUpload
            (
                {
                    url: 'Upfile.ashx', //用于文件上传的服务器端请求地址
                    type: 'post',
                    fileElementId: 'file1', //文件上传空间的id属性  <input type="file" id="file" name="file" />
                    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
                    {
                        $(".popupbox").show();
                    },
                    error: function (data, status, e)//服务器响应失败处理函数
                    {
                        alert(e);
                    }
                }
            )
            return false;
        }

           </script>
C#代码：

  context.Response.ContentType = "text/plain";
            System.Web.HttpFileCollection files =context.Request.Files;
            for (int fileCount = 0; fileCount < files.Count; fileCount++)
            {
                System.Web.HttpPostedFile postedfile = files[fileCount];

                string fileName = Guid.NewGuid().ToString().ToLower() + System.IO.Path.GetFileName(postedfile.FileName);
                if (!String.IsNullOrEmpty(fileName))
                {

                    string fileExtension = System.IO.Path.GetExtension(fileName);    //获取文件类型  
                    
                    //上传目录 
                    string nowtime = DateTime.Now.ToString("yyyy-MM-dd").Replace(" ", "_").Replace(":", "-");
                    string directory = System.Configuration.ConfigurationManager.AppSettings["k1"]+nowtime;
                    //文件全路径  
                    string path = directory + "/" + fileName;

                    //判断目录是否存在  
                    if (!Directory.Exists(directory))
                    {
                        Directory.CreateDirectory(directory);
                    }
                    //文件存在就删除文件  
                    if (File.Exists(path))
                    {
                        File.Delete(path);
                    }

                   //上传到服务器的路径  
                       postedfile.SaveAs(path);
                                   }
            }