线程的创建和退出

概念区分

  • 程序-磁盘上的可执行文件
  • 进程-程序执行代码所需资源的集合，不活泼的，懒惰的
  • 线程-程序执行代码的最小单位，活泼的，勤奋的

线程的运行（调度）原理

cpu时间切片

线程的创建

UI线程（主线程）-一般不做繁重的任务

非UI线程（工作线程）-一般做较繁重的任务

新建Windows桌面应用程序

image-20240711152942907

设计Dialog

image-20240711153922486

示例编辑框的ID为EDT_COUNTER

四个按钮的ID分别为BTN_START、BTN_PAUSE、BTN_STOP、BTN_CONTINUE

image-20240711154622175

image-20240711154642460

Sleep函数可以在暂停的时候减少线程对CPU的占用

image-20240711160124112

暂停线程SuspendThread

image-20240711161318219

恢复线程ResumeThread

image-20240711161351342

一个线程无法自己恢复自己，但是可以自己把自己挂起

image-20240711162319334

Counter.cpp

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// Counter.cpp : 定义应用程序的入口点。
//

#include "framework.h"
#include "Counter.h"

INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
  
    return (int)DialogBox(hInstance, MAKEINTRESOURCE(IDD_ABOUTBOX), NULL, About);
}

DWORD g_dwCounter = 0;
BOOL g_bContinue = TRUE;
HANDLE g_hThread = NULL;

DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    HWND hDlg = (HWND)lpParameter;
    while (true)
    {
        ++g_dwCounter;
        SetDlgItemInt(hDlg, EDT_COUNTER, g_dwCounter, FALSE);
#if 0
        if (g_bContinue)
        {
            ++g_dwCounter;
            SetDlgItemInt(hDlg, EDT_COUNTER, g_dwCounter, FALSE);
        }
        else
        {
            Sleep(1);
        }
#endif // 0

    }
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        switch (LOWORD(wParam))
        {
        case BTN_START:
        {
            g_hThread = CreateThread(NULL, 0, ThreadProc, hDlg, 0, NULL);
            break;
        }
        case BTN_PAUSE:
            //g_bContinue = FALSE;
            SuspendThread(g_hThread);
            break;
        case BTN_CONTINUE:
            //g_bContinue = TRUE;
            ResumeThread(g_hThread);
            break;
        case BTN_STOP:
            break;
        default:
            break;
        }
        break;

    case WM_CLOSE:
        EndDialog(hDlg, 0);
        break;
    }
    return (INT_PTR)FALSE;
}

运行后回弹出一个计数器窗口，点击开始就会开始计数，点击暂停会停止计数，点击继续又会重新计数

image-20240711164152840

线程的退出

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BOOL b_bStop = TRUE;//新建一个变量

DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    HWND hDlg = (HWND)lpParameter;
    while (!b_bStop)
    {
        ++g_dwCounter;
        SetDlgItemInt(hDlg, EDT_COUNTER, g_dwCounter, FALSE);
    }
    return 0;
}
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case BTN_STOP:
          CloseHandle(g_hThread);
          b_bStop = TRUE;
          break;

运行后点击停止可以退出进程

退出进程：ExitThread

image-20240711171053524

重命名

image-20240711171305038

TerminateThread也可以结束线程

image-20240711172157771

新建类

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class CFoo
{
public:
    CFoo() { MessageBox(NULL, "CFoo()", NULL, MB_OK); }
    ~CFoo() { MessageBox(NULL, "~CFoo()", NULL, MB_OK); }
};
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DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    CFoo foo;//初始化一个类
    HWND hDlg = (HWND)lpParameter;
}

新建动态链接库

image-20240711174239469

dllmain.cpp

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// dllmain.cpp : 定义 DLL 应用程序的入口点。
#include "pch.h"

__declspec(dllexport)void Foo()
{
    MessageBox(NULL, "Foo Called", NULL, MB_OK);
}
BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
        OutputDebugString("Dll1 DLL_PROCESS_ATTACH");
        break;
    case DLL_THREAD_ATTACH:
        OutputDebugString("Dll1 DLL_THREAD_ATTACH");
        break;
    case DLL_THREAD_DETACH:
        OutputDebugString("Dll1 DLL_THREAD_DETACH");
        break;
    case DLL_PROCESS_DETACH:
        OutputDebugString("Dll1 DLL_PROCESS_DETACH");
        break;
    }
    return TRUE;
}

Counter.cpp完整代码

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// Counter.cpp : 定义应用程序的入口点。
//

#include "framework.h"
#include "Counter.h"
__declspec(dllimport)void Foo();
#pragma comment(lib,"./Debug/Dll1.lib")

INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    Foo();
    return (int)DialogBox(hInstance, MAKEINTRESOURCE(IDD_ABOUTBOX), NULL, About);
}

DWORD g_dwCounter = 0;
BOOL g_bContinue = TRUE;
HANDLE g_hThread = NULL;
BOOL g_bStop = TRUE;

class CFoo
{
public:
    CFoo() { MessageBox(NULL, "CFoo()", NULL, MB_OK); }
    ~CFoo() { MessageBox(NULL, "~CFoo()", NULL, MB_OK); }
};
DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    CFoo foo;
    HWND hDlg = (HWND)lpParameter;
    while (TRUE)
    {
        if (g_bStop)
        {
            ExitThread(0x1234);
        }

        ++g_dwCounter;
        SetDlgItemInt(hDlg, EDT_COUNTER, g_dwCounter, FALSE);
#if 0
        if (g_bContinue)
        {
            ++g_dwCounter;
            SetDlgItemInt(hDlg, EDT_COUNTER, g_dwCounter, FALSE);
        }
        else
        {
            Sleep(1);
        }
#endif // 0
    }
    return 0;
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        switch (LOWORD(wParam))
        {
        case BTN_START:
        {
            g_bStop = FALSE;
            g_hThread = CreateThread(NULL, 0, ThreadProc, hDlg, 0, NULL);
            break;
        }
        case BTN_PAUSE:
            //g_bContinue = FALSE;
            SuspendThread(g_hThread);
            break;
        case BTN_CONTINUE:
            //g_bContinue = TRUE;
            ResumeThread(g_hThread);
            break;
        case BTN_STOP:
            TerminateThread(g_hThread, 0x123456);
            CloseHandle(g_hThread);
            //g_bStop = TRUE;
            break;
        default:
            break;
        }
        break;

    case WM_CLOSE:
        EndDialog(hDlg, 0);
        break;
    }
    return (INT_PTR)FALSE;
}

运行Counter.exe时会显示DLL_PROCESS_ATTACH，点击开始时会显示DLL_THREAD_ATTACH，点击停止时会显示DLL_THREAD_DETACH，关掉Counter.exe会显示DLL_PROCESS_DETACH

image-20240712150707609

image-20240711175444102