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: '/Pages/QzSpecialistic/Destroy.ashx',//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);
                                //$('#grid').datagrid('reload');
                                window.location.href = "DestroyDetail.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)
        {
			context.Response.Clear();
            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);//文件名 

                if (length > 0 && length < 512000)
                {
                    string type = System.IO.Path.GetExtension(postedFile[0].FileName);//文件类型
					
                    if (type == ".xml")
                    {
                        //读取文件
						QZ_SPECIALISTIC_ALLOCATION model = new QZ_SPECIALISTIC_ALLOCATION();
						QzSpecialisticDAL dal = new QzSpecialisticDAL();
						DataSet xmlDS = new DataSet();
						XmlTextReader reader = null;
                        try
                        {
							//加载xml -->取消根据路径读取XML方式
							//XmlDocument xmlDoc = new XmlDocument();
							//xmlDoc.Load(path+filename); //path+filename为文件路径
							//StringReader stream = new StringReader(xmlDoc.InnerXml);
							//从stream装载到XmlTextReader
							//XmlTextReader reader = new XmlTextReader(stream);

							//直接读取文件内容
							byte[] input = new byte[length];
							System.IO.Stream UpLoadStream = postedFile[0].InputStream;
							UpLoadStream.Read(input,length);
							UpLoadStream.Position = 0;
							System.IO.StreamReader sr = new System.IO.StreamReader(UpLoadStream,System.Text.Encoding.Default);
							//将xml文件转换为DataSet
							reader = new XmlTextReader(sr);
						    xmlDS.ReadXml(reader);

							for (int i = 0; i < xmlDS.Tables[0].Rows.Count; i++)
							{
								model.ID = xmlDS.Tables[0].Rows[i]["ID"].ToString();//主键ID

								if (!dal.AddOutDetailTemp(model))//插入数据库
								{
									string res = "{\"status\" : \"error\",\"msg\": \"数据录入失败！\"}";
									context.Response.Write(res);
									return;
								}
							}
							string path = HttpContext.Current.Server.MapPath("/XmlFiles/");//文件存放路径
							if (!System.IO.Directory.Exists(path))
								System.IO.Directory.CreateDirectory(path);//创建文件夹
							postedFile[0].SaveAs(path + filename);//保存文件内容 
							string res1 = "{\"status\" : \"success\",\"msg\": \"上传成功！\"}";
							context.Response.Write(res1);
                        }
                        catch 
                        {
                            string res = "{\"status\" : \"error\",\"msg\": \"数据库插入失败！\"}";
                            context.Response.Write(res);
                            return;
                        } 
                    }
                    else
                    {
                        string res = "{\"status\" : \"error\",\"msg\": \"只允许上传.xml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;
                }
            }
        }