使用AJAX调用在javascript中下载文件

Question

这是我的Java脚本代码，用于在按钮单击时从数据库下载文件，当按钮单击时此函数调用。 使用ajax调用我已经移到处理程序。

function DownloadDocument() {
    var CurrentUserEmpId = CurrentSelectedUser;
    Ext.Ajax.request({
        url: "UploadAttachment.ashx?mode=DownloadDocument&EmployeeId=" + CurrentUserEmpId,
        success: function (response) {
            var data = response.responseText;
        },
        failure: function (form, action) {
        }
    });
}

处理程序页面到了，我已经将文件的字节保存到byte [] buffer 。 这里的问题是下载无法正常工作。 由于Iam是初学者，所以我无法弄清楚问题所在。 请帮忙，谢谢。

case "DownloadDocument":

            WebClient web = new WebClient();
            try
            {
                byte[] buffer;

                var query2 = @"select LLD_Decleration_doc from (select  instance, Employee_id, lld_Decleration_doc, ROW_NUMBER() OVER(PARTITION BY Employee_id ORDER BY Update_Date DESC) Latest from [EManager].[dbo].[tax_benefit_declaration]) a where latest = 1 And Employee_id = @EmployeeId";

                using (SqlConnection con = new SqlConnection(db.ConnectionString))
                using (SqlCommand cmd = new SqlCommand(query2, con))
                {
                    SqlParameter param = cmd.Parameters.Add("@EmployeeId", SqlDbType.Int);
                    param.Value = EmployeeId;
                    con.Open();

                    buffer = (byte[])cmd.ExecuteScalar();
                    con.Close();
                }

                HttpResponse response = HttpContext.Current.Response;
                response.Clear();
                response.ClearContent();
                response.ClearHeaders();
                response.Buffer = true;
                response.ContentType = "APPLICATION/OCTET-STREAM";
                String Header = "Attachment; Filename=NewFile";
                response.AppendHeader("Content-Disposition", Header);
                context.Response.BinaryWrite(buffer);
                response.End();
            }
            catch { }
            break;
    }

Answer 1

这是很多次说过的话。 您不能通过Ajax调用来做到这一点。

您可以通过调用隐藏的iframe实现此目的，例如：

                var body = Ext.getBody();
                var comp = body.getById('hiddenform-iframe-download');
                if (!Ext.isEmpty(comp)) {
                    comp.remove();
                }
                body.createChild({
                    tag: 'iframe',
                    cls: 'x-hidden',
                    id: 'hiddenform-iframe-download',
                    name: 'iframe',
                    src: "yourContextToDownload?param1="+something
                });