C# ASP.NET 使用 FileUpload如何判断要上传文件大小

protected void btnup_Click(object sender, EventArgs e)
{
string fileName, fileExtension, filefold,size;
fileName = FileUpload1.FileName.ToString();
fileExtension = System.IO.Path.GetExtension(fileName).ToLower().Replace(".","");
if (FileUpload1.FileContent.Length != 0)
{
if (fileExtension == "jpg" || fileExtension == "jpeg" || fileExtension == "gif" || fileExtension == "rar" || fileExtension == "bmp")
{
size = Convert.ToDecimal(FileUpload1.FileContent.Length / 1000).ToString("#0.0");
filefold = DateTime.Now.Year.ToString() + "-" + DateTime.Now.Month.ToString();
filefold = filefold + "/";
string path = Server.MapPath("upfile/") + filefold;
DirectoryInfo directory = new DirectoryInfo(path);
if (!directory.Exists) //目录不存在创建
{directory.Create();}
//文件新名称
string name = DateTime.Now.ToString("yyyyMMdd HHmmss");
name = name.Replace("-", "");
name = name.Replace(":", "");
name = name.Replace(" ", "");
name = name.Trim() +"."+ fileExtension;
FileUpload1.SaveAs(path + "/" + name.Trim());
//保存数据
//model_upfile.titleid = Convert.ToInt64(title_id);
model_upfile.useid = STR.NameToId(Session["UserName"].ToString());
model_upfile.oldname = fileName;
model_upfile.newname = name;
model_upfile.Extension = fileExtension;
model_upfile.uptime = DateTime.Now.ToString();
model_upfile.type = type;
model_upfile.Filefold = filefold;
model_upfile.describer = txtms.Text.Trim();
model_upfile.down = 0;
model_upfile.Sizes = size.ToString();
model_upfile.timestring = ViewState["timestring"].ToString();
bll_upfile.Add(model_upfile);
Response.Write("<script>alert('上传文件成功!')</script>");
bind();
csg.BLL.T_User bll_user = new csg.BLL.T_User();
csg.Model.T_User model_user = new csg.Model.T_User();
//给楼主积分
model_user = bll_user.GetModel(STR.NameToId(Session["UserName"].ToString()));
model_user.scores += 1;
bll_user.Update(model_user);
}
else
{
Response.Write("<script>alert('上传失败!\\n只支持jpg|jpeg|gif|bmp|rar\\n如需上传其他文件请压缩后上传!')</script>");
}
}
else
{
Response.Write("<script>alert('请选择要上传文件!')</script>");
}

}

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