在线程内的套接字上接收文件时出错 [英] Error to receive file on socket inside a thread
问题描述
我无法接收包含PNG文件的字节数组.
在OnClientRead事件中执行代码后，它可以正常工作，在为线程传输时已经发生了MemoryStream错误，内容为:
I'm having trouble to receive a byte array containg a PNG file.
When the code is executed in OnClientRead event it works fine, already when transfered for a thread, happens an error of MemoryStream that says:
在扩展内存流时内存不足.
Out of memory while expanding memory stream.
此时:
if SD.State = ReadingSize then
if SD.State = ReadingSize then
我想知道如何解决此特定问题，还想知道如何接收包含文件或简单String的数据?
I want to know how to solve this specific trouble and also how can I check if I'm receiving a data that contains a file or a simple String?
代码:
type
TSock_Thread = class(TThread)
private
Socket: TCustomWinSocket;
public
constructor Create(aSocket: TCustomWinSocket);
procedure Execute; override;
end;
type
TInt32Bytes = record
case Integer of
0: (Bytes: array[0..SizeOf(Int32)-1] of Byte);
1: (Value: Int32);
end;
TSocketState = (ReadingSize, ReadingStream);
TSocketData = class
public
Stream: TMemoryStream;
Png: TPngImage;
State: TSocketState;
Size: TInt32Bytes;
Offset: Integer;
constructor Create;
destructor Destroy; override;
end;
{ ... }
constructor TSock_Thread.Create(aSocket: TCustomWinSocket);
begin
inherited Create(true);
Socket := aSocket;
FreeOnTerminate := true;
end;
procedure TSock_Thread.Execute;
var
s: String;
BytesReceived: Integer;
BufferPtr: PByte;
SD: TSocketData;
Item: TListItem;
begin
inherited;
while Socket.Connected do
begin
if Socket.ReceiveLength > 0 then
begin
s := Socket.ReceiveText;
{ SD := TSocketData(Socket.Data);
if SD.State = ReadingSize then
begin
while SD.Offset < SizeOf(Int32) do
begin
BytesReceived := Socket.ReceiveBuf(SD.Size.Bytes[SD.Offset],
SizeOf(Int32) - SD.Offset);
if BytesReceived <= 0 then
Exit;
Inc(SD.Offset, BytesReceived);
end;
SD.Size.Value := ntohl(SD.Size.Value);
SD.State := ReadingStream;
SD.Offset := 0;
SD.Stream.Size := SD.Size.Value;
end;
if SD.State = ReadingStream then
begin
if SD.Offset < SD.Size.Value then
begin
BufferPtr := PByte(SD.Stream.Memory);
Inc(BufferPtr, SD.Offset);
repeat
BytesReceived := Socket.ReceiveBuf(BufferPtr^,
SD.Size.Value - SD.Offset);
if BytesReceived <= 0 then
Exit;
Inc(BufferPtr, BytesReceived);
Inc(SD.Offset, BytesReceived);
until SD.Offset = SD.Size.Value;
end;
try
SD.Stream.Position := 0;
SD.Png.LoadFromStream(SD.Stream);
SD.Stream.Clear;
except
SD.Png.Assign(nil);
end;
Item := Form1.ListView1.Selected;
if (Item <> nil) and (Item.Data = Socket) then
Form1.img1.Picture.Graphic := SD.Png;
SD.State := ReadingSize;
SD.Offset := 0;
end; }
end;
Sleep(100);
end;
end;
procedure TForm1.ServerSocket1Accept(Sender: TObject; Socket: TCustomWinSocket);
var
TST: TSock_Thread;
begin
TST := TSock_Thread.Create(Socket);
TST.Resume;
end;
更新:
答案中的代码对我不起作用，因为ServerType=stThreadBlocking阻止了所有客户端与服务器的连接.因此，我正在搜索类似的内容(ServerType=stNonBlocking，TThread和OnAccept事件):
The code in the answer is not working for me because ServerType=stThreadBlocking blocks all clients connections with the server. And because of this, I'm searching for something like this (ServerType=stNonBlocking, TThread and OnAccept event):
type
TSock_Thread = class(TThread)
private
Png: TPngImage;
Socket: TCustomWinSocket;
public
constructor Create(aSocket: TCustomWinSocket);
procedure Execute; override;
procedure PngReceived;
end;
// ...
// ===============================================================================
constructor TSock_Thread.Create(aSocket: TCustomWinSocket);
begin
inherited Create(true);
Socket := aSocket;
FreeOnTerminate := true;
end;
// ===============================================================================
procedure TSock_Thread.PngReceived;
var
Item: TListItem;
begin
Item := Form1.ListView1.Selected;
if (Item <> nil) and (Item.Data = Socket) then
Form1.img1.Picture.Graphic := Png;
end;
procedure TSock_Thread.Execute;
var
Reciving: Boolean;
DataSize: Integer;
Data: TMemoryStream;
s, sl: String;
begin
inherited;
while Socket.Connected do
begin
if Socket.ReceiveLength > 0 then
begin
s := Socket.ReceiveText;
if not Reciving then
begin
SetLength(sl, StrLen(PChar(s)) + 1);
StrLCopy(@sl[1], PChar(s), Length(sl) - 1);
DataSize := StrToInt(sl);
Data := TMemoryStream.Create;
Png := TPngImage.Create;
Delete(s, 1, Length(sl));
Reciving := true;
end;
try
Data.Write(s[1], Length(s));
if Data.Size = DataSize then
begin
Data.Position := 0;
Png.LoadFromStream(Data);
Synchronize(PngReceived);
Data.Free;
Reciving := false;
end;
except
Png.Assign(nil);
Png.Free;
Data.Free;
end;
end;
Sleep(100);
end;
end;
procedure TForm1.ServerSocket1Accept(Sender: TObject; Socket: TCustomWinSocket);
var
TST: TSock_Thread;
begin
TST := TSock_Thread.Create(Socket);
TST.Resume;
end;
此代码在此行存在数据转换错误:
DataSize := StrToInt(sl);
This code has an error of conversion of data at this line:
DataSize := StrToInt(sl);
我该如何解决?
推荐答案
如何解决这个特定的问题
how solve this specific trouble
您没有按照本意使用TServerSocket线程.
You are not using TServerSocket threading the way it is meant to be used.
如果您想在stThreadBlocking模式下使用TServerSocket(请参阅我的其他答案有关如何使用TServerSocket在stNonBlocking模式下)，正确的方法是:
If you want to use TServerSocket in stThreadBlocking mode (see my other answer for how to use TServerSocket in stNonBlocking mode), the correct way is to:
- 从
TServerClientThread - 覆盖其虚拟
ClientExecute()方法完成I/O工作(通过TWinSocketStream) - 使用
TServerSocket.OnGetThread事件实例化线程.
如果不这样做，TServerSocket将创建自己的默认线程(在主线程中触发OnClient(Read|Write)事件)，这会干扰您的手动线程.
If you don't do this, TServerSocket will create its own default threads (to fire the OnClient(Read|Write) events in the main thread), which will interfere with your manual threads.
此外，您也不需要在我的答案中显示给您的状态机，
Also, you don't need the state machine that I showed you in my answer to your other question. That was for event-driven code. Threaded I/O code can be written linearly instead.
尝试更多类似的方法:
type
TSock_Thread = class(TServerClientThread)
private
Png: TPngImage;
procedure PngReceived;
protected
procedure ClientExecute; override;
end;
type
TInt32Bytes = record
case Integer of
0: (Bytes: array[0..SizeOf(Int32)-1] of Byte);
1: (Value: Int32);
end;
procedure TSock_Thread.ClientExecute;
var
SocketStrm: TWinSocketStream;
Buffer: TMemoryStream;
Size: TInt32Bytes;
Offset: Integer;
BytesReceived: Integer;
BufferPtr: PByte;
begin
SocketStrm := TWinSocketStream.Create(ClientSocket, 5000);
try
Buffer := TMemoryStream.Create;
try
Png := TPngImage.Create;
try
while ClientSocket.Connected do
begin
if not SocketStrm.WaitForData(100) then Continue;
Offset := 0;
while Offset < SizeOf(Int32) do
begin
BytesReceived := SocketStrm.Read(Size.Bytes[Offset], SizeOf(Int32) - Offset);
if BytesReceived <= 0 then Exit;
Inc(Offset, BytesReceived);
end;
Size.Value := ntohl(Size.Value);
Buffer.Size := Size.Value;
BufferPtr := PByte(Buffer.Memory);
Offset := 0;
while Offset < Size.Value do
begin
BytesReceived := SocketStrm.Read(BufferPtr^, Size.Value - Offset);
if BytesReceived <= 0 then Exit;
Inc(BufferPtr, BytesReceived);
Inc(Offset, BytesReceived);
end;
Buffer.Position := 0;
try
Png.LoadFromStream(Buffer);
except
Png.Assign(nil);
end;
Synchronize(PngReceived);
end;
finally
Png.Free;
end;
finally
Buffer.Free;
end;
finally
SocketStrm.Free;
end;
end;
procedure TSock_Thread.PngReceived;
var
Item: TListItem;
begin
Item := Form1.ListView1.Selected;
if (Item <> nil) and (Item.Data = ClientSocket) then
Form1.img1.Picture.Graphic := Png;
end;
procedure TForm1.ServerSocket1GetThread(Sender: TObject; ClientSocket: TServerClientWinSocket; var SocketThread: TServerClientThread);
begin
SocketThread := TSock_Thread.Create(False, ClientSocket);
end;
如何检查我是否接收到包含文件或简单字符串的数据?
how i can check if i'm receiving a data that contains a file or a simple String?
客户端需要将该信息发送到您的服务器.在发送实际数据之前，您已经在发送一个值以指定数据大小.您还应该在数据前添加一个值以指定数据的类型.然后，您可以根据需要根据数据类型处理数据.
The client needs to send that information to your server. You are already sending a value to specify the data size before sending the actual data. You should also preceed the data with a value to specify the data's type. Then you can handle the data according to its type as needed.
这篇关于在线程内的套接字上接收文件时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
