用TTcpClient和TTcpServer进行文件的传输

发送数据时有Sendln，SendBuf，SendStream。接收数据时有Receiveln,ReceiveBuf,当时我很奇怪为什么没有ReceiveStream。因为很自然的想到是对应关系的。但当时我不知道，发数据时是一小段一小段地发的

看看SendStream代码：

 function TBaseSocket.SendStream(AStream: TStream): Integer;
 var
   BufLen: Integer;
   Buffer: array[0..511] of Byte;
 begin
   Result := 0;
   if Assigned(AStream) then
   begin
     repeat
       BufLen := AStream.Read(Buffer, SizeOf(Buffer));
     until (BufLen = 0) or (SendBuf(Buffer, BufLen) = SOCKET_ERROR);
   end;
 end;

从以上代码可看到，SendStream一次最多发送512字节的内容，所以，我们这接收端循环用ReceiveBuf接收就可以了。不用像以前那样写得又复杂乱。

发送端(Client)代码：

 unit Unit1;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, StdCtrls, Sockets;

 type
   TForm1 = class(TForm)
     tcpclnt1: TTcpClient;
     btn1: TButton;
     procedure btn1Click(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 procedure TForm1.btn1Click(Sender: TObject);
 var
   f : TFileStream;//文件流
   i : Integer;
   fn : string;//文件名
 begin
   {用for循环是实现发送多个文件,如果只是发送一个文件，不用循环}
   for i := 1 to 11 do
   begin
     tcpclnt1.Connect; //连接服务端，我把TTcpClient的BlockMode设为bmBlocking
     fn := 'a' + IntToStr(i) + '.rar';
     f := TFileStream.Create('d:/send/' + fn,fmOpenRead); //用文件流以读方式打开要发送的文件
     tcpclnt1.Sendln(fn); //给对方发送文件名
     tcpclnt1.Sendln(IntToStr(f.Size)); //给对方发送文件大小
     tcpclnt1.SendStream(f); //发送文件流
     f.Free;//释放文件流
     tcpclnt1.Disconnect;//关闭连接
   end;
 end;

 end.

 

接收端(Server)代码：

 unit Unit1;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, Sockets;

 type
   TForm1 = class(TForm)
     tcpsrvr1: TTcpServer;
     procedure FormActivate(Sender: TObject);
     procedure tcpsrvr1Accept(Sender: TObject;
       ClientSocket: TCustomIpClient);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 procedure TForm1.FormActivate(Sender: TObject);
 begin
   tcpsrvr1.Open; //在OnActive事件中启动TCPServer的监听
 end;

 procedure TForm1.tcpsrvr1Accept(Sender: TObject;
   ClientSocket: TCustomIpClient);
 var
   f : TFileStream;  //文件流
   iFileSize : Integer; //文件大小
   iTotalRec : Integer; //总接收到的字节数,用来和文件大小比较,如果比文件大小的值要小,就还要继续接收
   iacRec    : Integer; //每一次ReceiveBuf实际接收到的字节数
   pbuf      : Pointer; //缓存指针
   i : Integer;
   fn : string; //文件名
 begin
     GetMem(pbuf,512); //我们一次最多也读取512字节
     try
       iTotalRec := 0;   //先把总接收到的字节数置零
       fn := ClientSocket.Receiveln; //接收文件名
       iFileSize := StrToInt(ClientSocket.Receiveln); //接收文件大小,接收到的字符串,要转成integer
       f := TFileStream.Create('d:/rec/'+ fn,fmCreate);//创建文件
       try
         {如果接收到的总字节数小于文件总字节数且实际接收字节数不为-1就一直循环接收}
         while iTotalRec < iFileSize  do
         begin
           iacRec := ClientSocket.ReceiveBuf(pbuf^,512);//一次接收512字节
           if iacRec = -1 then
             Break;//如果实际接收字节数是-1表示出错了,退出循环(应该写个log,或作出错处理什么的)
           f.Write(pbuf^,iacRec);//把接收到的数据写到文件流中
           Inc(iTotalRec,iacRec);//叠加接收到的总字节数
         end;
       finally
         f.Free; //释放流
       end;
     finally
       FreeMem(pbuf);//释放内存
     end;
 end;

 end.