Winsock学习笔记5：I/O Overlapped （重叠）模式

Winsock学习笔记5：I/O Overlapped （重叠）模式

 

unit  Unit1;

interface

uses
  WinSock2, Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TWorkThread  =   class (TThread)
   private
    FMemo: TMemo;
    FBuff:  array  [ 0 .. 10 ]  of  Char;
    FClientSocket: TSocket;
     procedure  ShowRecv;
   protected
     procedure  Execute; override ;
   public
     constructor  Create(Memo: TMemo; ClientSocket: TSocket);
   end ;

  TForm1  =   class (TForm)
    Memo1: TMemo;
    Button1: TButton;
    Timer1: TTimer;
     procedure  Timer1Timer(Sender: TObject);
     procedure  FormCreate(Sender: TObject);
   private
     {  Private declarations  }
   public
     {  Public declarations  }
   end ;

var
  Form1: TForm1;
  ServerSocket: TSocket;

implementation

{ $R *.dfm }

{  TWorkThread  }

constructor  TWorkThread.Create(Memo: TMemo; ClientSocket: TSocket);
begin
   inherited  Create(False);

  FMemo: =  Memo;
  FClientSocket: =  ClientSocket;
end ;

procedure  TWorkThread.Execute;
var
  WSBuff: WSABuf;
  EventTotal: Integer;
  AcceptOverLapped: WSAOverLapped;
  WSAEventArray:  array  [ 0 ..WSA_MAXIMUM_WAIT_EVENTS  -   1 ]  of  WSAEvent;

  Idx: Integer;
  ReceiveBytes: DWORD;
  Flags: DWORD;
  ByteTransferred: DWORD;
begin
   inherited ;
  FreeOnTerminate: =  True;
  EventTotal: =   0 ;

   // 创建事件
  WSAEventArray[EventTotal]: =  WSACreateEvent;
   // 置零
  ZeroMemory(@AcceptOverLapped, SizeOf(WSAOverLapped));
   // 关联事件
  AcceptOverLapped.hEvent: =  WSAEventArray[EventTotal];

  WSBuff.len: =   22 ;   // 缓冲区的长度要大于客户端发送的长度，如果小于客户端发送长度，会出现乱码
  WSBuff.buf: =  FBuff;
  Inc(EventTotal);

   while   not  Terminated  do
   begin
     // 收消息
    WSARecv(FClientSocket, @WSBuff, EventTotal, ReceiveBytes, Flags, @AcceptOverlapped,  nil );
     // 用WSAWaitForMultipleEvents检测是否有“事件”发生
    Idx: =  WSAWaitForMultipleEvents(EventTotal, @WSAEventArray[ 0 ], False, WSA_INFINITE, False);
     // 用WSAGetOverlappedResult取得结果
    WSAGetOverlappedResult(FClientSocket, @AcceptOverlapped, @ByteTransferred, False, Flags);
     // 显示收到的内容
    Synchronize(ShowRecv);

     // 清零AcceptOverLapped
    ZeroMemory(@AcceptOverLapped, SizeOf(WSAOverLapped));
     // 关联事件
    AcceptOverLapped.hEvent: =  WSAEventArray[Idx  -  WSA_WAIT_EVENT_ 0 ];

     // 重置Event
    WSAResetEvent(WSAEventArray[Idx  -  WSA_WAIT_EVENT_ 0 ]);
   end ;
end ;

procedure  TWorkThread.ShowRecv;
begin
  FMemo.Lines.Add(FBuff);
end ;

procedure  TForm1.FormCreate(Sender: TObject);
var
  WSData: TWSAData;
  LocalAddr: TSockaddr;
  SocketMode: Cardinal;
begin
   // 初始化Winsock
  WSAStartUp($ 202 , WSData);
   // 创建套接字
  ServerSocket: =  Socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
   // 设置LocalAddr的参数
  LocalAddr.sin_family: =  AF_INET;    // IPV4族
  LocalAddr.sin_addr.S_addr: =  INADDR_ANY; // 这里不能写Inet_addr( ' 127.0.0.1 ' )，负责会绑定失败，不清楚原因是什么;
  LocalAddr.sin_port: =  Htons( 1077 );  // Host To Net Short，主机字节顺序转为网络字节顺序
   // 绑定本机IP地址、端口，绑定之前先设置好LocalAddr的参数
  Bind(ServerSocket, @LocalAddr, SizeOf(LocalAddr));

  SocketMode: =   1 ;
  IoCtlSocket(ServerSocket, FIONBIO, SocketMode);

   // 开始监听
  Listen(ServerSocket,  5 );
end ;

procedure  TForm1.Timer1Timer(Sender: TObject);
var
  ClientAddr: TSockAddr;
  ClientAddrLen: Integer;
  ClientSocket: TSocket;
begin
   // 接受客户端连接，为对应的客户端创建独立的线程
  ClientAddrLen: =  SizeOf(ClientAddr);
  ClientSocket: =  Accept(ServerSocket, ClientAddr, ClientAddrLen);
   if  ClientSocket  <>  INVALID_SOCKET  then
    TWorkThread.Create(Memo1, ClientSocket);
end ;

end .

 

 

1.此代码只是为了学习函数的使用方法，为了使代码简单，此处使用Timer管理客户端连接，并为每个连接创建独立的线程，Overlapped的处理方式可在线程的执行部分查看，实际应用中不应该用这种模式；

2.此代码为消息型的重叠(I/O Overlapped)模式，还有一种“完成例程”模式（非完成端口）；