文件流操作（把文件流）

 public void SaveAsPic(string name)
        {
            Stream stream = Request.InputStream;
            // 把 Stream 转换成 byte[] 
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);
            // 把 byte[] 写入文件 
            FileStream fs = new FileStream("d:\\lct\\a" + name + ".jpg", FileMode.Create);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(bytes);
            bw.Close();
            fs.Close(); 
        }