在处理多用户聊天应用程序时,我一直困扰着让多字节字符在TServerSocket / TClientSocket上工作.
这是客户端将消息发送到服务器的部分：
procedure TChatForm.SendBtnClick(Sender: TObject);
var str : string;
begin
str := MsgLabel.Text;
ClientSocket.Socket.SendText('message' + separator + nickname + separator + str);
MsgLabel.Text := '';
add_text(MsgBox,MsgLabel,nickname+': '+str,'none');
end;
这是服务器解析收到的数据的方式：
procedure TServerForm.ServerSocketClientRead(Sender: TObject;Socket: TCustomWinSocket);
var
i,hnd : Integer;
recv : string;
arr : TStringArray; // type TStringArray = array of string;
begin
recv := Socket.ReceiveText;
hnd := Socket.Handle; //using this to avoid sending received data back to the client
arr := SplitStr(recv,separator);
//SplitStr is a function i use because TStringList.DelimitedText uses only a char as delimiter
// sending the data to the others users / but the expeditor - async error workaround
for i:=0 to ServerSocket.Socket.ActiveConnections-1 do begin
if ServerSocket.Socket.Connections[i].Handle <> hnd then
ServerSocket.Socket.Connections[i].SendText(recv);
end;
if arr[0] = 'connect' then begin
// adding the connected user to the tlistBox
Contacts.Items.Add(arr[1]);
// adding the connected message in the trichedit
add_text(MsgBox,SendMsg,arr[1]+' has connected !','green');
end else if arr[0] = 'disconnect' then begin
// removing the user from the online user list
Contacts.Items.Delete(Contacts.Items.IndexOf(arr[1]));
// adding the disconnected message in trichedit
add_text(MsgBox,arr[1]+' has disconnected !','red');
end else if arr[0] = 'message' then begin
// finally adding the message that user send in the TRichEdit
add_text(MsgBox,arr[1]+': '+arr[2],'none');
end;
end;
Socket.ReceiveText的示例如下：
- when user connects he sends the next message - connect^SEPARATOR^username - when a user sends a message - message^SEPARATOR^username^SEPARATOR^message_body
结构是ACTION SEPARATOR USERNAME EXTRA_DATA,这是我“保持”在线用户列表更新的方式.我是delphi的新手,如果有更简单的方法,请告诉我.
现在的问题是,如果我将多字节字符发送给用户并返回,则这些多字节字符作为问号“？”被接收.
– “ţ或ş”变成“？或？”
这里的Printscreen：
编辑2：好的,在完成所有更改之后,由于您的答案,我在尝试将服务器从客户端收到的数据发送回其他客户端时遇到了问题.那么这个问题有两个小问题：
>这是服务器向用户发送“全局”消息的方式.
procedure TServerForm.SendBtnClick(Sender: TObject);
var
i : Integer;
str : String;
begin
str := SendMsg.Text;
with ServerSocket.Socket do
begin
for i := 0 to ActiveConnections-1 do
SendString(Connections[i],TSocketBuffers(Connections[i].Data).OutBuffer,'global' + separator + str);
end;
add_text(MsgBox,str,'none');
SendMsg.Text := '';
end;
>这是服务器将从一个客户端收到的数据发送回其他活动连接的方式：
procedure TServerForm.ServerSocketClientRead(Sender: TObject;Socket: TCustomWinSocket);
var
Buffers: TSocketBuffers;
i: Integer;
RecvStr : String;
arr : TStringArray;
begin
Buffers := TSocketBuffers(Socket.Data);
if not Buffers.ReadInData(Socket) then Exit;
Buffers.InBuffer.Position := 0;
try
while ReadString(Buffers.InBuffer,RecvStr) do
begin
arr := SplitStr(RecvStr,separator);
with ServerSocket.Socket do
begin
for i := 0 to ActiveConnections-1 do
begin
if Connections[i] <> Socket then
SendString(Connections[i],arr[0]);
end;
end;
// [ .. some string processing stuff .. ]
end;
finally
CompactBuffer(Buffers.InBuffer);
end;
end;
现在,如果这两种方法是正确的,那么问题是客户端的读取数据,这就是如何在客户端解析数据的原理与ServerSocketClientRead(Sender：TObject; Socket：TCustomWinSocket)相同;
procedure TChatForm.ClientSocketRead(Sender: TObject; Socket: TCustomWinSocket);
var
Buffers: TSocketBuffers;
i: Integer;
RecvStr : String;
arr : TStringArray;
begin
Buffers := TSocketBuffers(Socket.Data);
if not Buffers.ReadInData(Socket) then Exit;
Buffers.InBuffer.Position := 0;
try
while ReadString(Buffers.InBuffer,RecvStr) do begin
ShowMessage(RecvStr); // testing if anything is received
// [[.. some string processing code ..]]
end;
finally
CompactBuffer(Buffers.InBuffer);
end;
end;
尝试将数据从客户端发送到服务器可以完美地工作,如图中所示(上图)字符串被解释为应该是.问题是要么尝试在ClientSocketRead方法中将数据发送回ServerSocketClientRead方法中的客户端.
更新3：所以我在另一台PC上启动了客户端,问题似乎是ClientSocketRead方法(如果ServerSocketClientRead – > SendString和全局SendBtn – > SendString是正确的);如果找到任何新的细节,我会不断更新.
解决方法
您需要远离SendText()和ReceiveText()方法,尤其是在使用非阻塞套接字时.它们不处理数据可能必须在多个数据包中发送的条件,并且数据包可以以较小的块或甚至多个数据包合并在一起.这些是您必须在TCP编程中处理的非常常见的条件.
SendText()只是将字符串按原样传递给SendBuf().如果它无法在单个发送中发送整个字符串,则不会尝试重新发送剩余的字符.所以你可以(也可能会)发送不完整的字符串.它确实返回实际发送的字节数,因此您可以在循环中调用SendText(),直到没有更多字符要发送.
ReceiveText()无法知道正在接收的字符串的长度.它只读取当前在套接字缓冲区中的任何内容并将其作为字符串返回.因此,这也存在读取不完整字符串,甚至读取多个(甚至部分)字符串的风险.
发送字符串的最佳方法是直接使用SendBuf()和ReceiveBuf().发送字符串时,要么在发送字符串数据之前发送字符串长度(以字节为单位),要么在字符串数据之后发送唯一的分隔符,而不会出现在字符串本身中.然后,接收器可以读取长度值,然后读取指定的字节数,或读取直到遇到分隔符.此外,在处理非ASCII字符串数据时,尤其是使用D2009的UnicodeString字符串类型时,您应该在传输过程中将字符串数据编码为通用格式,例如UTF-8.
如果您使用的是非阻塞套接字,则会变得更加复杂.如果套接字在发送/读取操作期间进入阻塞状态,则操作将失败并显示WSAEWOULDBLOCK错误代码,并且当套接字超出阻塞状态时您必须重复该操作.
如果发送操作失败并使用WSAEWOULDBLOCK,则将剩余数据缓冲到某处(并将任何未来的出站数据附加到该缓冲区的末尾,如果它不为空),直到OnWrite事件触发,然后发送缓冲区中的任何内容,删除成功发送的字节,直到它被清空或套接字再次阻塞(在这种情况下,你必须在发送剩余的缓冲区数据之前等待另一个OnWrite事件).
同样,当读取操作因WSAEWOULDBLOCK失败但您仍然期望数据时,您必须等待另一个OnRead事件触发,然后才能再次尝试读取,缓冲已接收的任何中间数据,直到您收到所有数据为止.您可以在处理之前预期的数据.
例如：
常用代码：
type
TSocketData = class
private
Socket: TCustomSocketSocket;
InBuffer: TMemoryStream;
OutBuffer: TMemoryStream;
function SendRawToSocket(Data: Pointer; DataLen: Integer): Integer;
procedure Compact(Buffer: TMemoryStream);
public
constructor Create(ASocket: TCustomSocketSocket);
destructor Destroy; override;
function BufferInboundData: Boolean;
procedure FlushOutboundData;
procedure BeginReading;
procedure EndReading;
function SendRaw(Data: Pointer; DataLen: Integer): Boolean;
function ReadRaw(Data: Pointer; DataLen: Integer): Boolean;
function SendInteger(Value: Integer): Boolean;
function ReadInteger(var Value: Integer): Boolean;
function SendInt64(Value: Int64): Boolean;
function ReadInt64(var Value: Int64): Boolean;
function SendString(const Str: String): Boolean;
function ReadString(var Str: String): Boolean;
function SendStream(Stream: TStream): Boolean;
function ReadStream(Stream: TStream): Boolean;
end;
constructor TSocketData.Create(ASocket: TCustomWinSocket);
begin
inherited;
Socket := ASocket;
InBuffer := TMemoryStream.Create;
OutBuffer := TMemoryStream.Create;
end;
destructor TSocketData.Destroy;
begin
InBuffer.Free;
OutBuffer.Free;
inherited;
end;
function TSocketData.SendRawToSocket(Data: Pointer; DataLen: Integer): Integer;
var
Bytes: PByte;
Ret: Integer;
begin
Result := 0;
Bytes := PByte(Data);
while DataLen > 0 do
begin
Ret := Socket.SendBuf(Bytes^,DataLen);
if Ret < 1 then
begin
if WSAGetLastError = WSAEWOULDBLOCK then Break;
Result := -1;
Exit;
end;
Inc(Bytes,Ret);
Dec(DataLen,Ret);
Inc(Result,Ret);
end;
end;
function TSocketData.BufferInboundData: Boolean;
var
RecvLen,OldSize: Integer;
begin
Result := False;
RecvLen := Socket.ReceiveLength;
if RecvLen < 1 then Exit;
OldSize := InBuffer.Size;
InBuffer.Size := OldSize + RecvLen;
try
RecvLen := Socket.ReceiveBuf((PByte(InBuffer.Memory)+OldSize)^,RecvLen);
if RecvLen < 1 then RecvLen := 0;
except
RecvLen := 0;
end;
InBuffer.Size := OldSize + RecvLen;
if RecvLen = 0 then Exit;
Result := True;
end;
procedure TSocketData.FlushOutboundData;
var
Ret: Integer;
begin
if OutBuffer.Size = 0 then Exit;
Ret := SendRawToSocket(OutBuffer.Memory,OutBuffer.Size);
if Ret < 1 then Exit;
OutBuffer.Position := Ret;
Compact(OutBuffer);
end;
procedure TSocketData.Compact(Buffer: TMemoryStream);
var
Remaining: Integer;
begin
if Buffer.Position = 0 then Exit;
Remaining := Buffer.Size - Buffer.Position;
if Remaining > 0 then
Move((PByte(Buffer.Memory) + Buffer.Position)^,Buffer.Memory^,Remaining);
Buffer.Size := Remaining;
end;
procedure TSocketData.BeginReading;
begin
InBuffer.Position := 0;
end;
procedure TSocketData.EndReading;
begin
Compact(InBuffer);
end;
function TSocketData.SendRaw(Data: Pointer; DataLen: Integer): Boolean;
var
Bytes: PByte;
Ret: Integer;
begin
Bytes := PByte(Data);
if OutBuffer.Size = 0 then
begin
Ret := SendRawToSocket(Bytes,DataLen);
if Ret = -1 then
begin
Result := False;
Exit;
end;
Inc(Bytes,Ret);
end;
if DataLen > 0 then
begin
OutBuffer.Seek(0,soEnd);
OutBuffer.WriteBuffer(Bytes^,DataLen);
end;
Result := True;
end;
function TSocketData.ReadRaw(Data: Pointer; DataLen: Integer): Boolean;
begin
Result := False;
if (InBuffer.Size - InBuffer.Position) < DataLen then Exit;
InBuffer.ReadBuffer(Data^,DataLen);
Result := True;
end;
function TSocketData.SendInteger(Value: Integer): Boolean;
begin
Value := htonl(Value);
Result := SendRaw(@Value,SizeOf(Value));
end;
function TSocketData.ReadInteger(var Value: Integer): Boolean;
begin
Result := ReadRaw(@Value,SizeOf(Value));
if Result then Value := ntohl(Value);
end;
type
TInt64Parts = packed record
case Integer of
0: (
LowPart: LongWord;
HighPart: LongWord);
1: (
QuadPart: Int64);
end;
function hton64(AValue: Int64): Int64;
var
LParts: TInt64Parts;
L: LongWord;
begin
LParts.QuadPart := AValue;
L := htonl(LParts.HighPart);
LParts.HighPart := htonl(LParts.LowPart);
LParts.LowPart := L;
Result := LParts.QuadPart;
end;
function ntoh64(AValue: Int64): Int64;
var
LParts: TInt64Parts;
L: LongWord;
begin
LParts.QuadPart := AValue;
L := ntohl(LParts.HighPart);
LParts.HighPart := ntohl(LParts.LowPart);
LParts.LowPart := L;
Result := LParts.QuadPart;
end;
function TSocketData.SendInt64(Value: Int64): Boolean;
begin
Value := hton64(Value);
Result := SendRaw(@Value,SizeOf(Value));
end;
function TSocketData.ReadInt64(var Value: Int64): Boolean;
begin
Result := ReadRaw(@Value,SizeOf(Value));
if Result then Value := ntoh64(Value);
end;
function TSocketData.SendString(const Str: String): Boolean;
var
S: UTF8String;
Len: Integer;
begin
S := UTF8String(Str);
Len := Length(S);
Result := SendInteger(Len);
if Result and (Len > 0) then
Result := SendRaw(PAnsiChar(S),Len);
end;
function TSocketData.ReadString(var Str: String): Boolean;
var
S: UTF8String;
Len: Integer;
begin
Result := False;
Str := '';
if not ReadInteger(Len) then Exit;
if (InBuffer.Size - InBuffer.Position) < Len then
begin
InBuffer.Seek(-SizeOf(Len),soCurrent);
Exit;
end;
if Len > 0 then
begin
SetLength(S,Len);
ReadRaw(PAnsiChar(S),Len);
Str := String(S);
end;
Result := True;
end;
function TSocketData.SendStream(Stream: TStream): Boolean;
var
Buf: array[0..1023] of Byte;
Len: Int64;
NumToSend: Integer;
begin
Len := Stream.Size - Stream.Position;
Result := SendInt64(Len);
if Result and (Len > 0) then
begin
repeat
if Len > SizeOf(Buf) then
NumToSend := SizeOf(Buf)
else
NumToSend := Integer(Len);
Stream.ReadBuffer(Buf[0],NumToSend);
Dec(Len,NumToSend);
Result := SendRaw(@Buf[0],NumToSend);
until (Len = 0) or (not Result);
end;
end;
function TSocketData.ReadStream(Stream: TStream): Boolean;
var
Len: Int64;
begin
Result := False;
if not ReadInt64(Len) then Exit;
if (InBuffer.Size - InBuffer.Position) < Len then
begin
InBuffer.Seek(-SizeOf(Len),soCurrent);
Exit;
end;
if Len > 0 then
Stream.CopyFrom(InBuffer,Len);
Result := True;
end;
客户代码：
procedure TChatForm.ClientSocketConnect(Sender: TObject; Socket: TCustomWinSocket);
begin
Socket.Data := TSocketData.Create(Socket);
end;
procedure TChatForm.ClientSocketDisconnect(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketData(Socket.Data).Free;
Socket.Data := nil;
end;
procedure TChatForm.ClientSocketWrite(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketData(Socket.Data).FlushOutboundData;
end;
procedure TChatForm.ClientSocketRead(Sender: TObject; Socket: TCustomWinSocket);
var
SocketData: TSocketData;
i: Integer;
RecvStr : String;
arr : TStringArray;
begin
SocketData := TSocketData(Socket.Data);
if not SocketData.BufferInboundData then Exit;
SocketData.BeginReading;
try
while SocketData.ReadString(RecvStr) do begin
ShowMessage(RecvStr); // testing if anything is received
// [[.. some string processing code ..]]
end;
finally
SocketData.EndReading;
end;
end;
procedure TChatForm.SendBtnClick(Sender: TObject);
var
SocketData: TSocketData;
begin
if ClientSocket1.Socket = nil then Exit;
SocketData := TSocketData(ClientSocket1.Socket.Data);
if SocketData = nil then Exit;
str := MsgLabel.Text;
if SocketData.SendString('message' + separator + nickname + separator + str) then
begin
MsgLabel.Text := '';
add_text(MsgBox,nickname + ': ' + str,'none');
end;
end;
服务器代码：
procedure TServerForm.ServerSocketClientConnect(Sender: TObject; Socket: TCustomWinSocket);
begin
Socket.Data := TSocketData.Create(Socket);
end;
procedure TServerForm.ServerSocketClientDisconnect(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketData(Socket.Data).Free;
Socket.Data := nil;
end;
procedure TServerForm.ServerSocketClientRead(Sender: TObject;Socket: TCustomWinSocket);
var
SocketData: TSocketData;
i: Integer;
RecvStr : String;
arr : TStringArray;
begin
SocketData := TSocketData(Socket.Data);
if not SocketData.BufferInboundData then Exit;
SocketData.BeginReading;
try
while SocketData.ReadString(RecvStr) do
begin
arr := SplitStr(RecvStr,separator);
with ServerSocket.Socket do
begin
for i := 0 to ActiveConnections-1 do
begin
if Connections[i] <> Socket then
TSocketData(Connections[i].Data).SendString(RecvStr);
end;
end;
if arr[0] = 'connect' then
begin
Contacts.Items.Add(arr[1]);
add_text(MsgBox,arr[1] + ' has connected !','green');
end
else if arr[0] = 'disconnect' then
begin
Contacts.Items.Delete(Contacts.Items.IndexOf(arr[1]));
add_text(MsgBox,arr[1] + ' has disconnected !','red');
end
else if arr[0] = 'message' then
begin
add_text(MsgBox,arr[1] + ': ' + arr[2],'none');
end;
end;
finally
SocketData.EndReading;
end;
end;
procedure TServerForm.ServerSocketClientWrite(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketData(Socket.Data).FlushOutboundData;
end;
procedure TServerForm.SendBtnClick(Sender: TObject);
var
i : Integer;
str : String;
begin
str := SendMsg.Text;
with ServerSocket.Socket do
begin
for i := 0 to ActiveConnections-1 do
TSocketData(Connections[i].Data).SendString('global' + separator + str);
end;
add_text(MsgBox,'none');
SendMsg.Text := '';
end;