數據結構實習之Huffman編譯碼（四）

4,基於異步套接字的消息通信：

注：詳細參看孫鑫老師的十六課視頻：

(1)因爲MFC自帶的AfxSocketInit函數初始化支持的是1.1版本的套接字，不適合異步套接字，我們需要調用的是Winsock2版本的套接字，那麼加載套接字庫的過程只能使用WSAStartup了。在CChatApp的InitInstance初始化函數中添加：

WORD wVersionRequested;
	WSADATA wsaData;
	int err;

	wVersionRequested =MAKEWORD( 2, 2 );

	err = WSAStartup( wVersionRequested, &wsaData );//加載套接字庫
	if ( err != 0 ) {
		return FALSE;
	}

	if ( LOBYTE( wsaData.wVersion ) != 2 ||
		HIBYTE( wsaData.wVersion ) != 2 ) {

		WSACleanup( );
		return FALSE;
	}

(2).StdAfx.h裏添加#include <winsock2.h>，在setting裏添加ws2_32.lib庫文件。

給CChatApp類添加析構函數，在其中添加WSACleanup來終止對套接字庫的使用。

給CChatDlg類添加成員變量SOCKET m_socket，並在構造函數中初始化爲0

給CChatDlg類添加析構函數，添加:

if(m_socket) //判斷socket是否有值

closesocket(m_socket);

(3).創建初始化函數InitSocket()，

BOOL CHuffmanDlg::InitSocket()

{
	m_socket=WSASocket(AF_INET,SOCK_DGRAM,0,NULL,0,0);
	if(INVALID_SOCKET==m_socket)
	{
		MessageBox("創建套接字失敗！");
		return FALSE;
	}
	SOCKADDR_IN addrSock;
	addrSock.sin_addr.S_un.S_addr=htonl(INADDR_ANY);
	addrSock.sin_family=AF_INET;
	addrSock.sin_port=htons(6000);
	
	if (SOCKET_ERROR==bind(m_socket,(SOCKADDR*)&addrSock,sizeof(SOCKADDR)))
	{
		MessageBox("綁定失敗！");
		return FALSE;
	}
	if (WSAAsyncSelect(m_socket,m_hWnd,WM_SOCK,FD_READ)==SOCKET_ERROR)
	{
		MessageBox("註冊網絡讀取失敗！");
		return FALSE;
	}

	return TRUE;
}
void CHuffmanDlg::OnSock(WPARAM wParam,LPARAM lParam)
{
	switch(LPARAM(lParam))
	{
	case FD_READ:
		WSABUF wsabuf;
		wsabuf.buf=new char[500];
		wsabuf.len=500;

		DWORD dwRead;
		DWORD dwFlag=0;
		SOCKADDR_IN addrFrom;
		int len=sizeof(SOCKADDR);
		CString codestr;//存儲接受到得編碼
		CString add;
		if(SOCKET_ERROR==WSARecvFrom(m_socket,&wsabuf,1,&dwRead,&dwFlag,
					(SOCKADDR*)&addrFrom,&len,NULL,NULL))
		{
			MessageBox("接受數據失敗！");
			return;
		}
		codestr.Format("%s",wsabuf.buf);
		add.Format("%s",inet_ntoa(addrFrom.sin_addr));
		DecodeSockMes(add,codestr);
		//codelist.Format("%s",wsabuf[1].buf);
		//SetDlgItemText(IDC_EDIT_DECODEREC,codelist);
		break;
	}
}

(4)消息響應函數的處理：

void CHuffmanDlg::OnButtonSend() 

{
	// TODO: Add your control notification handler code here
	DWORD dwIP;
	CString codeSend="";
	WSABUF wsabuf;

	DWORD dwSend;
	int len;
	((CIPAddressCtrl*)GetDlgItem(IDC_IPADDRESS1))->GetAddress(dwIP);

	SOCKADDR_IN addrTo;
	addrTo.sin_addr.S_un.S_addr=htonl(dwIP);
	addrTo.sin_family=AF_INET;
	addrTo.sin_port=htons(6000);

	GetDlgItemText(IDC_EDIT_CODE,codeSend);
	if (codeSend=="")
	{
		MessageBox("編碼爲空！");
		return;
	}
	CString s;//葉子節點數
	s.Format("%d",m_num);
	codeSend=s+codeSend;


	for (int i=0;i<m_num;i++)
	{
		codeSend+=m_plist.GetItemText(i,0);
		codeSend+=m_plist.GetItemText(i,3);
	}
	len=codeSend.GetLength();
	wsabuf.buf=codeSend.GetBuffer(len);
	wsabuf.len=len+1;

	OnClear();//清空所有內容
	if(SOCKET_ERROR==WSASendTo(m_socket,&wsabuf,1,&dwSend,0,
			(SOCKADDR*)&addrTo,sizeof(SOCKADDR),NULL,NULL))
	{
		MessageBox("發送數據失敗！");
		return;
	}
}

(5)消息接收函數：

void CHuffmanDlg::OnSock(WPARAM wParam,LPARAM lParam)
{
	switch(LPARAM(lParam))
	{
	case FD_READ:
		WSABUF wsabuf;
		wsabuf.buf=new char[500];
		wsabuf.len=500;

		DWORD dwRead;
		DWORD dwFlag=0;
		SOCKADDR_IN addrFrom;
		int len=sizeof(SOCKADDR);
		CString codestr;//存儲接受到得編碼
		CString add;
		if(SOCKET_ERROR==WSARecvFrom(m_socket,&wsabuf,1,&dwRead,&dwFlag,
					(SOCKADDR*)&addrFrom,&len,NULL,NULL))
		{
			MessageBox("接受數據失敗！");
			return;
		}
		codestr.Format("%s",wsabuf.buf);
		add.Format("%s",inet_ntoa(addrFrom.sin_addr));
		DecodeSockMes(add,codestr);
		//codelist.Format("%s",wsabuf[1].buf);
		//SetDlgItemText(IDC_EDIT_DECODEREC,codelist);
		break;
	}
}