Question

我有问题。当我从服务器获取文件时，即使我的文件被下载但我收到错误“此文件正在被其他应用程序使用”

编辑：对不起，我的代码丢失了。这是服务器部分。我在启动后执行此方法。并等待来自客户的命令。 goto是一个标签。 ıf工作（例如“文件启动”）完成然后清洁和免费连接。这是多线程套接字应用程序。重复直到部分文件下载。我希望我会解释。

我的代码

procedure ConnectionWorker(P: Pointer);
label cleanup;
Var
  sData1: TStringDYNArray;
  cSock: TClientSocket;
  scHost, scSendData, scFirstData, scFullData:String;
  sBuff, sString:String;
  bPackInfos:TPacketInformation;
  scByte, sComm:Byte;
  sBitMap:TBitmap;
  sJPEG:TJPEGImage;
  fFile:TFileStream;
  scPort,lRecvLen, cRead, x,y:Integer;
  arrBuffer:array[0..1000] of Byte;
  bBuff:array[0..4095] of Byte;
  eRatio:Extended;
  sFirstCap, sDifCap, sSecondCap, sCompStream:TMemoryStream;
  pCompStream:TCompressionStream;
  cThread, cKillThread:Cardinal;
Begin
  scHost := PInfo(P)^.scHost;
  scSendData := PInfo(P)^.scData;
  scPort := PInfo(P)^.scPort;
  scByte := PInfo(P)^.scPackHead;
  sFirstCap := TMemoryStream.Create;
  sSecondCap := TMemoryStream.Create;
  cSock := TClientSOcket.Create;
  cSock.Connect(scHost,scPort);
  if cSock.Connected then begin
    scFirstData := scSendData;
    If SendPacket(cSock,scByte, scFirstData) then begin
      repeat
        scFullData := '';
        ZeroMemory(@arrBuffer[0], 1001);
        lRecvLen := cSock.ReceiveBuffer(arrBuffer[0],1001);
        if cSock.Connected = false then break;
        SetLength(sBuff,lRecvLen);
        MoveMemory(@sBuff[1],@arrBuffer[0],lRecvLen);
        scFullData := scFullData + sBuff;
        repeat
          bPackInfos := VerifyPacket(scFullData);
          scFullData := bPackInfos.PacketLeft;
          sString := bPackInfos.PacketCommand;
          sComm := bPackInfos.PacketByte;
          if bPackInfos.PacketFinished = False then
            break;
          case sComm of

            PACK_QUERYCOMPRESSEDFILE:
              begin
                if FileExists(sString) then begin
                  try
                    sFirstCap.LoadFromFile(sString);
                    sFirstCap.Position := 0;
                    sCompStream := TMemoryStream.Create;
                    pCompStream := TCompressionStream.Create(clMax,sCompStream);
                    pCompStream.CopyFrom(sFirstCap, sFirstCap.Size);
                    pCompStream.Free;
                    sString := '';
                    SetLength(sString,sCompStream.Size);
                    SendPacket(cSock,PACK_COMPRESSEDTRANSFERFILE,IntToStr(sCompStream.Size));
                    sCompStream.Position := 0;
                    sCompStream.Read(sString[1],sCompStream.Size);
                    SendPacket(cSock,PACK_COMPRESSEDDOWNLOADFILE,sString);
                  except
                    SendPacket(cSock,PACK_COMPRESSEDTRANSFERFILE,IntToStr(0));
                  end;
                  goto cleanup;
                end;
              end;
            PACK_QUERYFILE:
              begin
                if FileExists(sString) then begin
                  try
                    sFirstCap.LoadFromFile(sString);
                    sFirstCap.Position := 0;
                    sString := '';
                    SetLength(sString,sFirstCap.Size);
                    SendPacket(cSock,PACK_DOWNLOADFILE,IntToStr(sFirstCap.Size));
                    sFirstCap.Read(sString[1],sFirstCap.Size);
                    SendPacket(cSock,PACK_TRANSFERFILE,sString);
                  except
                    SendPacket(cSock,PACK_DOWNLOADFILE,IntToStr(0));
                  end;
                  goto cleanup;
                end;
                if FileExists(sString) then begin
                  try
                    fFile := TFileStream.Create(sString, fmOpenRead);
                    Repeat
                      ZeroMemory(@bBuff[0],4096);
                      cRead := fFile.Read(bBuff[0],Length(bBuff));
                      If (cRead <= 0) Then Break;
                      If cSock.SendBuffer(bBuff[0],cRead) <= 0 then break;
                    Until 1 = 3;
                    fFile.Free;
                  except
                  end;                                                                  
                end;                                                 
                goto cleanup;
              end;                                                       
            PACK_FILESTART:  // problem is here                                                                                    
              begin                                                                
                try
                  fFile := TFileStream.Create(sString, fmCreate);
                  Repeat
                    ZeroMemory(@bBuff[0],4096);
                    cRead := cSock.ReceiveBuffer(bBuff[0],4096); --> stopped on debug. no execute next line. 
                    if cRead <= 0 then break;
                    fFile.Write(bBuff,cRead);
                  Until 1 = 3;

                Finally
                 fFile.Free;
                end;
                goto cleanup;
              end;                                             



          end;                                     
        until scFullData = '';
      until 1 = 3;
    end;
  end;
  cleanup:
    try
      sFirstCap.Free;
      sSecondCap.Free;
    except
    end;
  FreeMem(p);
  cSock.Disconnect;
End;

Answer 1

一些想法......

1）代码不检查字节是否可供读取。见行： “cRead：= cSock.ReceiveBuffer（bBuff [0]，4096）; - ＆gt;在调试时停止。没有执行下一行。” 并注意这是如何在重复循环中。如果没有更多数据要读，会发生什么？（例如过早断开连接）

2）看起来它有重入代码...我没有看到任何检查阻止两个不同的线程试图在同一个文件上获取fmCreate

3）关于goto的评论，这似乎是从VBA（ON Error Gosub）转换而来的。我强烈建议为Delphi写一些更原生的东西

希望这有帮助

Delphi

1 个答案: