有时候导出Excel时需要根据某些条件筛选数据，然后将数据通过NPOI生成Excel并导出。组织数据时可以通过放到一个表单中，某些场景是使用脚本(如：jquery)组织一个form(通过字符串拼接)，然后将这个from的转换成jquery对象或者Dom对象，再调用对应的submit方法。
例子如下，有一个html页面
<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> ???<title></title> ???<meta charset="utf-8" /></head><body> ???<input type="button" value="导出Excel" id="btnExport" /> ???<script src="Scripts/jquery-3.1.1.min.js"></script> ???<script type="text/javascript"> ???????$(function () { ???????????$("#btnExport").click(function () { ???????????????var formHtml = "<form action=‘DownLoadHandler.ashx‘ method=‘post‘ target=‘_blank‘>"; ???????????????formHtml += "<input type=‘hidden‘ name=‘username‘ value=‘admin‘ />"; ???????????????formHtml += "<input type=‘hidden‘ name=‘password‘ value=‘abc‘ />"; ???????????????formHtml += "</form>"; ???????????????$(formHtml).submit(); ???????????}); ???????}); ???</script></body></html>这里是ASP.NET web应用程序，有一个一般处理程序，它通过判断筛选条件（这里是用户名和密码，实际当中可能是某些查询条件，用户向数据库查询数据等），然后导出Excel
using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Web;namespace WebApplication1{ ???/// <summary> ???/// DownLoadHandler 的摘要说明 ???/// </summary> ???public class DownLoadHandler : IHttpHandler ???{ ???????public void ProcessRequest(HttpContext context) ???????{ ???????????if (context.Request.Form["username"] == "admin" && context.Request.Form["password"] == "abc") ???????????{ ???????????????context.Response.ContentType = "application/octet-stream"; ???????????????context.Response.AddHeader("Content-Disposition", "attachment;filename=persons.xlsx"); ???????????????byte[] bytes = File.ReadAllBytes(context.Server.MapPath("~/SysFolder/Persons.xlsx")); ???????????????context.Response.BinaryWrite(bytes); ???????????} ???????????else ???????????{ ???????????????context.Response.ContentType = "text/plain"; ???????????????context.Response.Write("没有找到数据，导出excel失败"); ???????????} ???????} ???????public bool IsReusable ???????{ ???????????get ???????????{ ???????????????return false; ???????????} ???????} ???}}通过浏览器浏览，点击按钮发现没有提交表单，网络监视里没有发出请求
查看开发人员工具中的控制台，发现提示Form submission canceled because the form is not connected
该问题需要将组织的form追加到文档的body中，然后再提交，于是修改代码
<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> ???<title></title> ???<meta charset="utf-8" /></head><body> ???<input type="button" value="导出Excel" id="btnExport" /> ???<script src="Scripts/jquery-3.1.1.min.js"></script> ???<script type="text/javascript"> ???????$(function () { ???????????$("#btnExport").click(function () { ???????????????var formHtml = "<form action=‘DownLoadHandler.ashx‘ method=‘post‘ target=‘_blank‘>"; ???????????????formHtml += "<input type=‘hidden‘ name=‘username‘ value=‘admin‘ />"; ???????????????formHtml += "<input type=‘hidden‘ name=‘password‘ value=‘abc‘ />"; ???????????????formHtml += "</form>"; ???????????????var form = $(formHtml); ???????????????$(document.body).append(form); ???????????????form.submit(); ???????????}); ???????}); ???</script></body></html>刷新页面，再次提交，发现正常
参考链接：https://stackoverflow.com/questions/42053775/getting-error-form-submission-canceled-because-the-form-is-not-connected
Jquery组织Form表单提交之Form submission canceled because the form is not connected
原文地址：http://www.cnblogs.com/godbell/p/7455677.html