导出CSV

public FileResult ExportExcel()
{
var sbHtml = new StringBuilder();
sbHtml.Append("<table border='1' cellspacing='0' cellpadding='0'>");
sbHtml.Append("<tr>");
var lstTitle = new List<string> { "编号", "姓名", "年龄", "创建时间" };
foreach (var item in lstTitle)
{
sbHtml.AppendFormat("<td style='font-size: 14px;text-align:center;background-color: #DCE0E2; font-weight:bold;' height='25'>{0}</td>", item);
}
sbHtml.Append("</tr>");

for (int i = 0; i < 1000; i++)
{
sbHtml.Append("<tr>");
sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", i);
sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>屌丝{0}号</td>", i);
sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", new Random().Next(20, 30) + i);
sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", DateTime.Now);
sbHtml.Append("</tr>");
}
sbHtml.Append("</table>");

//第一种:使用FileContentResult
byte[] fileContents = Encoding.Default.GetBytes(sbHtml.ToString());
return File(fileContents, "application/ms-excel", "fileContents.xls");

//第二种:使用FileStreamResult
var fileStream = new MemoryStream(fileContents);
return File(fileStream, "application/ms-excel", "fileStream.xls");

//第三种:使用FilePathResult
//服务器上首先必须要有这个Excel文件,然会通过Server.MapPath获取路径返回.
var fileName = Server.MapPath("~/Files/fileName.xls");
return File(fileName, "application/ms-excel", "fileName.xls");
}

js的代码：
window.location.href = "Export"; 

后台代码：

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public FileResult Export() {     return File(Server.MapPath("/Data/Export.xls"), "application/ms-excel", "Export.xls"); }