web文件上传的问题

DirectoryInfo directory = new DirectoryInfo(hidDir);

                    if (directory.GetFiles().Length.ToString() == chunks)

                    {

                        //FileInfo[] fileInfoArray = directory.GetFiles();

                        int size = int.Parse(context.Request.Params["size"]);

                        //byte[] bytes = new byte[size];

                        int c = int.Parse(chunks);

                        FileStream f = new FileStream(path + serverFileName, FileMode.Create | FileMode.Append);

                        BinaryWriter AddWriter = new BinaryWriter(f);

                        for (int i = 0; i < c; i++)

                        {

                            FileStream addFile = new FileStream(hidDir + "/$" + i + ".aw", FileMode.Open);



                            int fsLen = (int)addFile.Length;

                            byte[] heByte = new byte[fsLen];

                            addFile.Read(heByte, 0, heByte.Length);

                            //获得上传的分片数据流



                            //将上传的分片追加到临时文件末尾

                            AddWriter.Write(heByte);

                            //关闭BinaryReader文件阅读器

                            addFile.Close();

                            addFile.Dispose();

                        }

                        AddWriter.Close();

                        AddWriter.Dispose();

                        deleteDirAndFile(hidDir);//删除隐藏文件夹

                    }