1 #include <Windows.h>
 2 int main()
 3 {
 4     //异步操作最大的好处就是不会阻塞
 5     HANDLE hFile = CreateFile(TEXT("Demo.txt"), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, nullptr, OPEN_ALWAYS, FILE_FLAG_OVERLAPPED, nullptr);
 6     if (hFile != INVALID_HANDLE_VALUE)
 7     {
 8         //Read
 9         BYTE bReadBuffer[100] = { 0 };
10         OVERLAPPED oRead = { 0 };
11         oRead.hEvent = CreateEvent(nullptr, TRUE, FALSE, TEXT("ReadEvent")); //事件内核对象
12         ReadFile(hFile, bReadBuffer, sizeof(bReadBuffer), nullptr, &oRead);
13 
14         //Write
15         BYTE bWriteBuffer[10] = { 1,2,3,4,5,6,7,8,9,0 };
16         OVERLAPPED oWrite = { 0 };
17         oWrite.hEvent = CreateEvent(nullptr, TRUE, FALSE, TEXT("WriteEvent")); //事件内核对象
18         ReadFile(hFile, bWriteBuffer, sizeof(bWriteBuffer), nullptr, &oWrite);
19 
20         //Do Same ....
21         //其他的线程
22         HANDLE hOverLapped[2] = { 0 };
23         hOverLapped[0] = oRead.hEvent;
24         hOverLapped[1] = oWrite.hEvent;
25 
26         while (true)
27         {
28             DWORD dwCase = WaitForMultipleObjects(2, hOverLapped, FALSE, INFINITE);
29             switch (dwCase - WAIT_OBJECT_0)
30             {
31             case 0:
32                 //读完成
33                 break;
34             case 1:
35                 //写完成
36                 break;
37             }
38         }
39     }
40     else
41     {
42         //GetLastError();
43     }
44     
45     return 0;
46 }

 1 #include <Windows.h>
 2 
 3 VOID CALLBACK FileIOCompletionReadRoutine(
 4     _In_        DWORD dwErrorCode,
 5     _In_        DWORD dwNumberOfBytesTransfered,
 6     _Inout_        LPOVERLAPPED lpOverladded
 7     )
 8 {
 9     MessageBox(nullptr, TEXT("Read"), TEXT("Read"), MB_OK);
10 }
11 
12 int main()
13 {
14     //发送请求
15     //做自己的事情
16     //判断请求是否完成
17 
18     //发送请求 -》完成后，操作系统提醒我
19     //可提醒I/0操作
20     //APC
21     //工厂（进程）-》工人（线程）
22     //                    APC机制 当线程空闲的时候（前提） -》 APC列表中的事情（自动执行）
23     //                            线程为可提醒的窗台下
24     //        就是线程空闲的时候
25     //MessageBox        -》   阻塞（闲下来） 不是可提醒状态
26     //Wait Sleep 函数 可提醒的状态
27 
28 
29     HANDLE hFile = CreateFile(TEXT("Demo.txt"), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, nullptr, OPEN_ALWAYS, FILE_FLAG_OVERLAPPED, nullptr);
30     
31     if (hFile != INVALID_HANDLE_VALUE)
32     {
33         const UINT uLen = 255;
34         BYTE bReadBuf[uLen] = { 0 };
35         OVERLAPPED oRead = { 0 };
36         oRead.Offset = 5;
37         ReadFileEx(hFile, bReadBuf, uLen, &oRead, FileIOCompletionReadRoutine);
38 
39         SleepEx(100, TRUE);
40         //DWORD WINAPI SleepEx(
41         //    _In_ DWORD dwMilliseconds,
42         //    _In_ BOOL  bAlertable
43         //    );
44 
45         //干自己的事情 Do Some......
46         //运行程序 没有弹出消息框
47         //SleepEx    Wait 可以使线程成为空闲状态
48         //while (10)
49         //{
50         //    Sleep(100);
51         //}
52     }
53 
54 
55     return 0;
56 }