procedure TServerThread.ClientExecute;
var
    pStream:TWinSocketStream;
    buffer:Pointer;
    readText,SendText:string;
    i:integer;
Const
{读客户端令牌时使用的缓冲区大小，因为它们都是一些字符串，所以定义为1024byte足够了}
    ReadLen=1024;
begin

{创建连接流对象，以便和客户端交流}
      pStream:=TWinSocketStream.Create(ClientSocket,60000);
      try
      {ClientSocket是TServerClientThread 类内置的一个对象，它是和客户端连接的套接字}
      while (not Terminated) and ClientSocket.Connected do
      begin
        try
        {分配读数据缓冲区}
        Buffer:=AllocMem(readLen);
        if PStream.WaitForData(6000) then
        begin
          pStream.Read(Buffer^,ReadLen);    ///读取客户端发送data,数据是从缓存区中读取。 readText:=Pchar(Buffer);
          FreeMem(buffer);
          //客户端请求验证是否有可以更新的文件
          if ReadText = Key_Clt[1] then
          begin
            Synchronize(listItemAdd);//多线程中同步信息需要调用的方法。
            SendText:=Key_Srv[1]+stringstostring(FilesNameSepstr,filesName,true);
            {特别注意SendText后应该加上索引1,指定write方法从SendText第一个字符
            开始读，否则默认从0开始}
            pStream.Write(SendText[1],length(sendtext)+1);//向客户端写数据
          end

except

    errorRaise:=true;
    Terminate;

end;

end;
        finally
          pstream.Free;
          ClientSocket.Close;
      end;
end;

由于Socket选择 使用ctBlock的方式，所以在接收、发送数据时，就不能依靠在OnRead,OnWrite中读取和写入数据了，因为该事件在ctBlock下根本就不能被触发。
   解决的方法就是不间断的监听线程

while (not Terminated) and ClientSocket.Connected do
begin

end;

读取数据的时机：if PStream.WaitForData(6000) then
        begin
        end;

转自：http://gykthh.blog.163.com/blog/static/6453464200852710710790/

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delphi的帮助中有Writing client threads 和 Writing server threads代码示例。
procedure TMyClientThread.Execute;
var
TheStream: TWinSocketStream;
buffer: string;
begin
{ create a TWinSocketStream for reading and writing }
TheStream := TWinSocketStream.Create(ClientSocket1.Socket, 60000);
try
{ fetch and process commands until the connection or thread is terminated }
while (not Terminated) and (ClientSocket1.Active) do
begin
try
GetNextRequest(buffer); { GetNextRequest must be a thread-safe method }

{ write the request to the server }
TheStream.Write(buffer, Length(buffer) + 1);
{ continue the communication (e.g. read a response from the server) }
...
except
if not(ExceptObject is EAbort) then
Synchronize(HandleThreadException); { you must write HandleThreadException }
end;
end;
finally
TheStream.free;
end;
end;

procedure TMyServerThread.ClientExecute;
var
Stream : TWinSocketStream;
Buffer : array[0 .. 9] of Char;
begin
{ make sure connection is active }
while (not Terminated) and ClientSocket.Connected do
begin
try
Stream := TWinSocketStream.Create(ClientSocket, 60000);
try
FillChar(Buffer, 10, 0); { initialize the buffer }
{ give the client 60 seconds to start writing }
if Stream.WaitForData(60000) then

begin
if Stream.Read(Buffer, 10) = 0 then { if can‘t read in 60 seconds }
ClientSocket.Close; { close the connection }
{ now process the request }
...
end
else
ClientSocket.Close; { if client doesn‘t start, close }
finally
Stream.Free;
end;
except
HandleException;
end;
end;
end;

delphi中使用SocketStream读写数据的技巧