js+ajax实现获取文件大小的方法_javascript技巧

public partial class XMLHttpPost : System.Web.UI.Page
{
 protected void Page_Load(object sender, EventArgs e)
 {
 try
 {
 XmlDocument xmlDocumenet = new XmlDocument();
 xmlDocumenet.Load(Request.InputStream);
 string type = xmlDocumenet.SelectSingleNode("descendant::Type").InnerText;
 string returnMessage = string.Empty;
 switch (type.Trim())
 {
 case "TicketLoanResult":
 returnMessage = GetTicketLoanResult(xmlDocumenet);
 break;
 default:
 break;
 }
 Response.ContentType = "text/xml";
 Response.Write(returnMessage);
 }
 catch (Exception exceptional)
 {
 //如果有錯誤則返回錯誤信息（Xml格式）
 string errorMessage = "" + exceptional.Message + "";
 Response.ContentType = "text/xml";
 Response.Write(errorMessage);
 }
 finally
 {
 Response.End();
 }
 }
 private string GetTicketLoanResult(XmlDocument input)
 {
 XmlNode item = input.SelectSingleNode("descendant::TicketType");
 string ticketType = item.InnerText.Trim();
 FileStream stream = new FileStream(ticketType,FileMode.Open);
 return stream.Length.ToString();
 }
}