上传文件读取流时长度总是为0,该如何处理

System.Net.HttpWebRequest                req = System.Net.HttpWebRequest.Create("http://192.168.186.94/fortest.ashx") as System.Net.HttpWebRequest;            req.Method = System.Net.WebRequestMethods.Http.Post;            System.IO.MemoryStream ms = new System.IO.MemoryStream();            using (System.IO.FileStream fs = new System.IO.FileStream(@"XXX", System.IO.FileMode.Open))            {                Int32 by = -1;                while ((by = fs.ReadByte()) != -1)                {                    ms.WriteByte((Byte)by);                }            }            Byte[] buffer = ms.ToArray();            req.ContentLength = buffer.Length;            req.ContentType = "application/x-www-form-urlencoded";            req.Headers.Add("UserName", "mgsg");            req.Headers.Add("Pwd", "123456789");            req.Headers.Add("FileName", "yiyuan.emr");            req.Headers.Add("Kind", "zhongyi");            req.Headers.Add("Field", "jilu");            System.IO.Stream str = req.GetRequestStream();            str.Write(buffer, 0, buffer.Length);            System.Net.HttpWebResponse response = req.GetResponse() as System.Net.HttpWebResponse;            if (response.StatusCode == System.Net.HttpStatusCode.OK)            {                using (System.IO.StreamReader                    sr = new System.IO.StreamReader(response.GetResponseStream(), Encoding.GetEncoding("gb2312")))                {                    Console.Write(sr.ReadToEnd());                }            }            else                Console.WriteLine(response.StatusCode);

HttpPostedFile upFile = up_file.PostedFile;//HttpPostedFile对象,用来读取上传图片的属性            fileLength = upFile.ContentLength;//记录文件的长度   try   {    if(fileLength==0)//当文件长度为0的时候    {     txtMessage.Text = "请选择要上传的文件!";    }    else    {     byte[] fileByte = new byte[fileLength];//用图片的长度来初始化一个字节数组存储临时的图片文件     Stream fileStream = upFile.InputStream;//建立文件流对象     fileStream.Read(fileByte,0,fileLength);//读取图片数据到临时存储体fileByte,0为数据指针位置,fileLength为数据长度     string connString = "Data Source=192.168.1.250;database=image;uid=pwqzc;pwd=cn0088";     SqlConnection conn = new SqlConnection(connString);//初始化数据库连接     string insertStr = "insert into image (image_data,image_content_type,image_description,image_size) values (@image_data,@image_content_type,@image_description,@image_size)";     //插入数据库语句     SqlCommand comm = new SqlCommand(insertStr,conn);     comm.Parameters.Add(new SqlParameter("@image_data",SqlDbType.Image));//添加参数     comm.Parameters["@image_data"].Value = fileByte;//给参数赋值     comm.Parameters.Add(new SqlParameter("@image_content_type",SqlDbType.VarChar,50));     comm.Parameters["@image_content_type"].Value = upFile.ContentType;//记录图片类型     comm.Parameters.Add(new SqlParameter("@image_description",SqlDbType.VarChar,50));     comm.Parameters["@image_description"].Value = txtDescription.Text;//把其他的表单数据上传     comm.Parameters.Add(new SqlParameter("@image_size",SqlDbType.Int,4));     comm.Parameters["@image_size"].Value = upFile.ContentLength;//记录图片长度,读取数据的时候使用     conn.Open();//打开数据库连接     comm.ExecuteNonQuery();//添加数据     conn.Close();//关闭数据库     txtMessage.Text = "你已经成功的上传了图片";    }   }   catch(Exception ex)   {       txtMessage.Text = ex.Message.ToString();   }  } }