unit U_Client;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, Math,
  StdCtrls, ComCtrls;

type
  Tfrm_Client = class(TForm)
    SaveDialog1: TSaveDialog;
    IdTCPClient1: TIdTCPClient;
    Button1: TButton;
    StatusBar1: TStatusBar;
    Edit1: TEdit;
    Label1: TLabel;
    Edit2: TEdit;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frm_Client: Tfrm_Client;

implementation

{$R *.dfm}

procedure Tfrm_Client.Button1Click(Sender: TObject);
var
  cmd: string;
  ASize, TotalSize: Int64;
  AFileStream: TFileStream;
begin
  IdTCPClient1.Host := Edit1.Text; //連接主機
  IdTCPClient1.Port := StrToIntDef(Edit2.Text, 9925); //端口
  IdTCPClient1.Connect; //連接
  try
    IdTCPClient1.WriteLn('BEGIN'); //提示服務器開始接收
    cmd := IdTCPClient1.ReadLn;
    //以“|”符號分離文件名
    SaveDialog1.FileName := Copy(cmd, Pos('|', cmd) + 1, Length(cmd));
    if not SaveDialog1.Execute then
    begin
      IdTCPClient1.WriteLn('CANCEL'); //告訴服務器取消
      IdTCPClient1.Disconnect; //斷開連接
      exit;
    end;
    TotalSize := StrToInt(Copy(cmd, 0, Pos('|', cmd) - 1)); //分離文件大小
    //建立文件流準備接收
    AFileStream := TFileStream.Create(SaveDialog1.FileName, fmCreate);
    try //循環開始接受
      repeat
        IdTCPClient1.WriteLn(IntToStr(AFileStream.Size));//發送當前傳輸的位置
        ASize := Min(TotalSize - AFileStream.Size, IdTCPClient1.RecvBufferSize);
        //選擇剩余大小和緩沖區大小小的一個作為傳輸的大小
        IdTCPClient1.ReadStream(AFileStream, ASize); //接收流
        StatusBar1.SimpleText := Format('當前傳輸位置%d/大小%d', [AFileStream.Size, TotalSize]);
        Application.ProcessMessages;
      until AFileStream.Size = TotalSize; //大小一致了表示結束
    finally
      AFileStream.Free; //釋放文件流
    end;
    IdTCPClient1.WriteLn('END'); //提示服務器傳輸完成
    StatusBar1.SimpleText := '傳輸完成...';
  except
    StatusBar1.SimpleText := '連接服務器失敗或者對方已經中斷傳輸！';
  end;
  IdTCPClient1.Disconnect;
end;

end.