前台代码：

1.新增引用：

<script type="text/javascript" src="/scripts/ajaxfileupload.js"></script>

<asp:FileUpload ID="fup" runat="server" Width="70"></asp:FileUpload>
<input id="Button1" type="button" value="导入" onclick="Upload()"/>

<script type="text/javascript">
    function Upload() {


       var file = $("#fup").val(); 
       if(file==""){ 
       alert("请选择上传的文件"); 
       return; 
      }


      $.ajaxFileUpload(
         {
           url: 'Handler.ashx?r=' + $('#checktime').val() + '&n=<%= regioncode %> &c=' + $('#regionname').val() + '&i=<%= id %>',//需要链接到服务器地址
           secureuri: false,fileElementId: 'fup',//文件选择框的id属性
           dataType: 'json',success: function (data) {


             if (data.status == "success") {
               alert(data.msg);
               window.location.href = "Inspection.aspx";
             }
             else {
               alert(data.msg);
             }
           },error: function (data,status,e) {
             alert(e);  //就是在这弹出“语法错误” 
           }
         }
       );
    }

   </script>

public void ProcessRequest(HttpContext context)
        {
            string time = context.Request.QueryString["r"];//获取巡查时间
            string regioncode = context.Request.QueryString["n"];//获取地区代码
            string regionname = context.Request.QueryString["c"];//获取地区名称
            string operatorid = context.Request.QueryString["i"];//获取操作人ID
            context.Response.Clear();
            context.Response.ContentType = "text/html";
            HttpFileCollection postedFile = context.Request.Files;
            //判断是否有数据
            if (postedFile != null && postedFile.Count > 0)
            {
                int length = postedFile[0].ContentLength;//文件大小
                string filename = System.IO.Path.GetFileName(postedFile[0].FileName);
                //string filename = System.IO.Path.GetFileNameWithoutExtension(postedFile[0].FileName);
                if (length > 0 && length < 512000)
                {
                    string type = System.IO.Path.GetExtension(postedFile[0].FileName);
                    if (type == ".xls" || type == ".xlsx" || type == ".doc" || type == ".docx")
                    {
                        newland.Model.Inspection inspection = new newland.Model.Inspection();
                        string id="";
                        try
                        {
                            DataTable dt = WebBusiness.EvaluationManagement.InspectionDal.GetInspectionId();
                            id = dt.Rows[0]["id"].ToString();
                            inspection.ID = id;
                            inspection.REGIONCODE = regioncode;
                            inspection.REGIONNAME = regionname;
                            inspection.INSPECTIONDATE = Convert.ToDateTime(time);
                            inspection.ATTACHMENT = filename;
                            inspection.OPERATOR = Convert.ToInt32(operatorid);
                        }
                        catch 
                        {
                            string res = "{\"status\" : \"error\",\"msg\": \"数据库插入失败！\"}";
                            context.Response.Write(res);
                            return;
                        }
                        if (WebBusiness.EvaluationManagement.InspectionDal.InsertInspection(inspection))//插入数据库
                        {
                            try
                            {
                                string tempPath = "";
                                tempPath = System.Web.HttpContext.Current.Server.MapPath("/inspection/" + regionname);
                                if (!System.IO.Directory.Exists(tempPath))
                                    System.IO.Directory.CreateDirectory(tempPath);//创建文件夹
                                postedFile[0].SaveAs(tempPath + "/" + id + type);
                                string res = "{\"status\" : \"success\",\"msg\": \"上传成功！\"}";
                                context.Response.Write(res);
                            }
                            catch
                            {
                                WebBusiness.EvaluationManagement.InspectionDal.DeteleInspection(id);
                                string res = "{\"status\" : \"error\",\"msg\": \"文件上传失败！\"}";
                                context.Response.Write(res);
                                return;
                            }

                        }
                        else
                        {
                            string res = "{\"status\" : \"error\",\"msg\": \"数据录入失败！\"}";
                            context.Response.Write(res);
                            return;
                        }
                    }
                    else
                    {
                        string res = "{\"status\" : \"error\",\"msg\": \"只允许上传.xls,.xlsx,.doc,.docx类型的文件！\"}";
                        context.Response.Write(res);
                        return;
                    }
                }
                else
                {
                    string res = "{\"status\" : \"error\",\"msg\": \"文件过大！\"}";
                    context.Response.Write(res);
                    return;
                }
            }
        }