當麻許的超技八

            var httpPostedFile = HttpContext.Current.Request.Files["uploadfile"];
            httpPostedFile.SaveAs(AppDomain.CurrentDomain.BaseDirectory + "files"+Path.DirectorySeparatorChar + "xxx.jpg");

        <input id="File1" name="File1" type="file" />
        <button id="btn1" type="button">Upload File</button>
        <span id="statustxt"></span>

        $('#btn1').click(function () {
            UploadFile();
        });


        function UploadFile() {

            var data = new FormData();
            var files = $("#File1").get(0).files;

            if (files.length > 0) {
                data.append("uploadfile", files[0]);
            }
            var ajaxRequest = $.ajax({
                type: "POST",
                url: "/upload2.aspx",
                contentType: false,
                processData: false,
                data: data,
                xhr: function () {
                    var xhr = new window.XMLHttpRequest();
                    //用來處理上傳的事件
                    xhr.upload.addEventListener("progress", function (evt) {
                        //顯示進度
                        $('#statustxt').html(Math.round(evt.loaded / evt.total * 100) + "%");
                    }, false);

                    return xhr;
                }
            });
            ajaxRequest.done(function (xhr, textStatus) {
                alert('上傳完成!');
            });
        }