MFC中多线程的应用有哪些?

MFC中多线程的应用有哪些?


MFC中多线程的应用

-------------------------------------------------------------------------------

我试着用自已的话来表述线程的概念,还有很短时间里编的一个小示例程序(不知恰当不?,也不知能说得清不..),见笑了.

线程其实和标准的windows主程序(WinMain)没啥两样...主程序其实是一个特殊的线程,称为主线程而已,其实你完全可以把线程想象成和winmain一起**同时运行**,但是** 可以相互访问(即在一个地址空间) **的一些小的WinMain程序.它和主线程一样,里面可以创建窗口,获取消息,等等..

由于线程们在一个地址空间且同时运行,所以会造成一些麻烦。因为我们编程都要用别人的函数库,而他们的函数库里面往往会有很多静态或全局的状态或中间变量,有着很复杂的相互依赖关系,如果执行某个功能不串行化(所谓串行化,也就是只能等一个功能调用返回后,另一个线程才能调用,不可以同时调用),就会造成大乱.这对线程来说,有术语称同步,windows为我们提供了很多同步的方法,MFC也提供了一些同步核心对象的类封装.对于某个功能调用库来说,叫线程安全.比如MFC的类库并不是线程安全的.

现在我举个刚刚自编的例子来简单说明这些概念。下面的一个对话框应用是多线程的.演示两个小动画:

(1)第一个动画由主线程的Timer来驱动,第二个动画由主线所创建的工作线程来驱动.分别显示在不同的位置.之所以我要加入Timer,也是为了形成线程驱动和timer驱动的对照,这是动画的两种驱动方式(还有在idle中驱动的)。

(2)这两个动画永远是不同的.也就是比如:一个是变哭,一个就会变笑,等那个变笑了,这个就变哭.动画图片来自于OICQ中的Face目录下,一般同样的头像会oicq会带三个图片(*-1.bmp,*-2.bmp,*-3.bmp),*-2.bmp是变灰的图片,我就取了1和3的图片来作动画.

这个程序的几个关键要注意的:

(1)主线程用PostThreadMessage和工作线程通信.工作线程用PeekMessage来取回消息。为了简单起见,我只用了一个WM_QUIT的消息来指示工作线程退出.

(2)主线程和工作线程同时调用了一个DisplayFace函数来进行动画显示.为了让两个动画一哭一笑做到不同,采用了CCriticalSection来进行同步.


示例如下:

(1)先用appwizards生成一个MFC的Dialog应用模板,假定对话框类为CTest01Dlg。

(2)再添入两个oicq的bmp文件到资源中去

(3)添加一个按钮(button)到对话框上.用作启动、停止动画的button

(4)用ClassWizard为button/onclick及dlg/ontimer生成事件响应函数,

(5)用Resource Symbol加入一个标识定义IDC_TIMER1

(6)在ClassView中为CTest01Dlg加入以下成员变量和成员函数

CriticalSection ccs;

CBitmap bm[2];

CWinThread* pMyThread;

static UINT MyThreadProc( LPVOID pParam);

void DisplayFace(CPoint r);

实现文件中加入相应代码(见下面)

(7)stdafx.h中加入#include

源代码如下,凡是我新加的代码周围都有注释包围,其它是ClassWizards自动写的:

// stdafx.h : include file for standard system include files,

// or project specific include files that are used frequently, but

// are changed infrequently

file://

#if !defined(AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_)

#define AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_

#if _MSC_VER > 1000

#pragma once

#endif // _MSC_VER > 1000

#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers

#include // MFC core and standard components

#include // MFC extensions

#include // MFC support for Internet Explorer 4 Common Controls

file://加入头引用主要是CCriticalSection对象的定义.

#include

file://加入结束

#ifndef _AFX_NO_AFXCMN_SUPPORT

#include // MFC support for Windows Common Controls

#endif // _AFX_NO_AFXCMN_SUPPORT

file://{{AFX_INSERT_LOCATION}}

// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_)

// test01Dlg.h : header file

file://

#if !defined(AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_)

#define AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_

#if _MSC_VER > 1000

#pragma once

#endif // _MSC_VER > 1000

/////////////////////////////////////////////////////////////////////////////

// CTest01Dlg dialog

class CTest01Dlg : public CDialog

{

// Construction

public:

file://加入

CBitmap bm[2];

CCriticalSection ccs;

CWinThread* pMyThread;

static UINT MyThreadProc( LPVOID pParam);

void DisplayFace(CPoint r);

CTest01Dlg(CWnd* pParent = NULL); // standard constructor

file://加入结束

// Dialog Data

file://{{AFX_DATA(CTest01Dlg)

enum { IDD = IDD_TEST01_DIALOG };

// NOTE: the ClassWizard will add data members here

file://}}AFX_DATA

// ClassWizard generated virtual function overrides

file://{{AFX_VIRTUAL(CTest01Dlg)

protected:

virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support

file://}}AFX_VIRTUAL

// Implementation

protected:

HICON m_hIcon;

// Generated message map functions

file://{{AFX_MSG(CTest01Dlg)

virtual BOOL OnInitDialog();

afx_msg void OnSysCommand(UINT nID, LPARAM lParam);

afx_msg void OnPaint();

afx_msg HCURSOR OnQueryDragIcon();

afx_msg void OnButton1();

afx_msg void OnTimer(UINT nIDEvent);

file://}}AFX_MSG

DECLARE_MESSAGE_MAP()

};

file://{{AFX_INSERT_LOCATION}}

// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_)

// test01Dlg.cpp : implementation file

file://

#include "stdafx.h"

#include "test01.h"

#include "test01Dlg.h"

#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif

/////////////////////////////////////////////////////////////////////////////

// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog

{

public:

CAboutDlg();

// Dialog Data

file://{{AFX_DATA(CAboutDlg)

enum { IDD = IDD_ABOUTBOX };

file://}}AFX_DATA

// ClassWizard generated virtual function overrides

file://{{AFX_VIRTUAL(CAboutDlg)

protected:

virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support

file://}}AFX_VIRTUAL

// Implementation

protected:

file://{{AFX_MSG(CAboutDlg)

file://}}AFX_MSG

DECLARE_MESSAGE_MAP()

};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)

{

file://{{AFX_DATA_INIT(CAboutDlg)

file://}}AFX_DATA_INIT

}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)

{

CDialog::DoDataExchange(pDX);

file://{{AFX_DATA_MAP(CAboutDlg)

file://}}AFX_DATA_MAP

}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)

file://{{AFX_MSG_MAP(CAboutDlg)

// No message handlers

file://}}AFX_MSG_MAP

END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////

// CTest01Dlg dialog

CTest01Dlg::CTest01Dlg(CWnd* pParent /*=NULL*/)

: CDialog(CTest01Dlg::IDD, pParent)

{

file://{{AFX_DATA_INIT(CTest01Dlg)

// NOTE: the ClassWizard will add member initialization here

file://}}AFX_DATA_INIT

// Note that LoadIcon does not require a subsequent DestroyIcon in Win32

m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);

file://加入

pMyThread =NULL;

file://加入结束

}

void CTest01Dlg::DoDataExchange(CDataExchange* pDX)

{

CDialog::DoDataExchange(pDX);

file://{{AFX_DATA_MAP(CTest01Dlg)

// NOTE: the ClassWizard will add DDX and DDV calls here

file://}}AFX_DATA_MAP

}

BEGIN_MESSAGE_MAP(CTest01Dlg, CDialog)

file://{{AFX_MSG_MAP(CTest01Dlg)

ON_WM_SYSCOMMAND()

ON_WM_PAINT()

ON_WM_QUERYDRAGICON()

ON_BN_CLICKED(IDC_BUTTON1, OnButton1)

ON_WM_TIMER()

file://}}AFX_MSG_MAP

END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////

// CTest01Dlg message handlers

BOOL CTest01Dlg::OnInitDialog()

{

CDialog::OnInitDialog();

// Add "About..." menu item to system menu.

// IDM_ABOUTBOX must be in the system command range.

ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);

ASSERT(IDM_ABOUTBOX < 0xF000);

CMenu* pSysMenu = GetSystemMenu(FALSE);

if (pSysMenu != NULL)

{

CString strAboutMenu;

strAboutMenu.LoadString(IDS_ABOUTBOX);

if (!strAboutMenu.IsEmpty())

{

pSysMenu->AppendMenu(MF_SEPARATOR);

pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);

}

}

// Set the icon for this dialog. The framework does this automatically

// when the application''s main window is not a dialog

SetIcon(m_hIcon, TRUE); // Set big icon

SetIcon(m_hIcon, FALSE); // Set small icon

// TODO: Add extra initialization here

file://加入

bm[0].LoadBitmap (IDB_BITMAP1);

bm[1].LoadBitmap (IDB_BITMAP3);

file://加入结束

return TRUE; // return TRUE unless you set the focus to a control

}

void CTest01Dlg::OnSysCommand(UINT nID, LPARAM lParam)

{

if ((nID & 0xFFF0) == IDM_ABOUTBOX)

{

CAboutDlg dlgAbout;

dlgAbout.DoModal();

}

else

{

CDialog::OnSysCommand(nID, lParam);

}

}

void CTest01Dlg::OnPaint()

{

if (IsIconic())

{

CPaintDC dc(this); // device context for painting

SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

// Center icon in client rectangle

int cxIcon = GetSystemMetrics(SM_CXICON);

int cyIcon = GetSystemMetrics(SM_CYICON);

CRect rect;

GetClientRect(&rect);

int x = (rect.Width() - cxIcon + 1) / 2;

int y = (rect.Height() - cyIcon + 1) / 2;

// Draw the icon

dc.DrawIcon(x, y, m_hIcon);

}

else

{

CDialog::OnPaint();

}

}

HCURSOR CTest01Dlg::OnQueryDragIcon()

{

return (HCURSOR) m_hIcon;

}

file://加入

void CTest01Dlg::OnButton1()

{

static BOOL bStarted=FALSE;

if (!bStarted){

SetTimer(IDC_TIMER1,500,NULL);

pMyThread=AfxBeginThread(MyThreadProc,this);

}else{

if (pMyThread){

pMyThread->PostThreadMessage (WM_QUIT,0,0);

::WaitForSingleObject(pMyThread->m_hThread ,INFINITE);

pMyThread=NULL;

}

KillTimer(IDC_TIMER1);

}

bStarted=!bStarted;

((CButton*)GetDlgItem(IDC_BUTTON1))->SetWindowText((bStarted?_T("停止"):_T("启动")));

}

void CTest01Dlg::OnTimer(UINT nIDEvent)

{

if (nIDEvent==IDC_TIMER1)

DisplayFace(CPoint(10,10));

CDialog::OnTimer(nIDEvent);

}

void CTest01Dlg::DisplayFace(CPoint p)

{

static int i=0;

ccs.Lock ();

BITMAP bmo;

bm[i].GetObject (sizeof(bmo),&bmo);

CClientDC dc(this);

CDC bmpDC;

bmpDC.CreateCompatibleDC (&dc);

bmpDC.SelectObject (&bm[i]);

dc.BitBlt (p.x ,p.y ,bmo.bmWidth,bmo.bmHeight,&bmpDC,0,0,SRCCOPY);

i++;

if (i==sizeof(bm)/sizeof(bm[0])) i=0;

ccs.Unlock ();

}

UINT CTest01Dlg::MyThreadProc(LPVOID pParam)

{

CTest01Dlg *me=(CTest01Dlg *)pParam;

MSG msg;

while(!PeekMessage(&msg,NULL,0,0,PM_NOREMOVE)){

me->DisplayFace (CPoint(100,10));

::Sleep (200);

}

return 0;

}

file://加入结束