1. // 002_异步IO.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
    2. //
    3. #include <windows.h>
    4. #include <stdio.h>
    6. struct MyOverlapped : public OVERLAPPED  {
    7.     MyOverlapped()
    8.     {
    9.         // 将OVERLAPPED部分填充为0
    10.         memset(this, 0, sizeof(OVERLAPPED));
    11.         pBuff = NULL;
    12.     }
    13.     char *pBuff;
    14.     ~MyOverlapped() {
    15.         if (pBuff) {
    16.             delete pBuff;
    17.         }
    18.     }
    19. };
    23. DWORD WINAPI ThreadProc(VOID* pArg)
    24. {
    25.     MyOverlapped* pOv = (MyOverlapped*)pArg;
    26.     WaitForSingleObject(pOv->hEvent,-1);
    27.     printf("读取偏移:[%d]的IO任务完成, 实际读取到的字节数:%d"
    28.            "读取到的内容是:%s",
    29.            pOv->Offset,
    30.            pOv->InternalHigh,
    31.            pOv->pBuff);
    32.     return 0;
    33. }
    35. int main()
    36. {
    37.     HANDLE hFile = INVALID_HANDLE_VALUE;
    38.     hFile = CreateFile(
    39.         L"002_异步IO.cpp",
    40.         GENERIC_READ,/*读写方式:只读*/
    41.         FILE_SHARE_READ,/*共享方式: 共享读*/
    42.         NULL,/*安全描述符*/
    43.         OPEN_EXISTING,/*创建标志:存在时才打开*/
    44.         FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,/*文件属性和标志:正常属性|重叠IO标志 */
    45.         NULL);
    48.     MyOverlapped* ov = new MyOverlapped;
    49.     ov->Offset = 0;// 表示从第20个字节开始读
    50.     ov->pBuff = new char[200];
    51.     memset(ov->pBuff, 0, 200);
    52.     DWORD read = 0;
    53.     ov->hEvent = CreateEvent(NULL,/*安全描述符*/
    54.                             FALSE,/*是否需要手动重置信号*/
    55.                             FALSE,/*初始是否有信号*/
    56.                             NULL/*事件对象名(一般为了跨进程使用)*/);
    58.     ReadFile(hFile, ov->pBuff, 100, &read, ov);
    60.     MyOverlapped* ov2 =new MyOverlapped;
    61.     ov2->Offset = 100;
    62.     ov2->hEvent = CreateEvent(NULL,/*安全描述符*/
    63.                             FALSE,/*是否需要手动重置信号*/
    64.                             FALSE,/*初始是否有信号*/
    65.                             NULL/*事件对象名(一般为了跨进程使用)*/);
    67.     ov2->pBuff = new char[200];
    68.     memset(ov2->pBuff, 0, 200);
    69.     ReadFile(hFile, ov2->pBuff,100, &read, ov2);
    71.     CreateThread(0, 0, &ThreadProc, ov2, 0, 0);
    72.     CreateThread(0, 0, &ThreadProc, ov, 0, 0);
    74.     while ( 1 )
    75.     {
    76.         Sleep(100);
    77.     }
    78. }