MFC中多线程的应用
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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
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#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
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#include
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#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
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#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:
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CBitmap bm[2];
CCriticalSection ccs;
CWinThread* pMyThread;
static UINT MyThreadProc( LPVOID pParam);
void DisplayFace(CPoint r);
CTest01Dlg(CWnd* pParent = NULL); // standard constructor
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// Dialog Data
enum { IDD = IDD_TEST01_DIALOG };
// NOTE: the ClassWizard will add data members here
// ClassWizard generated virtual function overrides
file://{{AFX_VIRTUAL(CTest01Dlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
// Implementation
protected:
HICON m_hIcon;
// Generated message map functions
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);
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
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#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
enum { IDD = IDD_ABOUTBOX };
// ClassWizard generated virtual function overrides
file://{{AFX_VIRTUAL(CAboutDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
// Implementation
protected:
DECLARE_MESSAGE_MAP()
};
CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
file://{{AFX_DATA_INIT(CAboutDlg)
}
void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
file://{{AFX_DATA_MAP(CAboutDlg)
}
BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
file://{{AFX_MSG_MAP(CAboutDlg)
// No message handlers
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
// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
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pMyThread =NULL;
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}
void CTest01Dlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
file://{{AFX_DATA_MAP(CTest01Dlg)
// NOTE: the ClassWizard will add DDX and DDV calls here
}
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()
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
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bm[0].LoadBitmap (IDB_BITMAP1);
bm[1].LoadBitmap (IDB_BITMAP3);
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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;
}
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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;
}
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