ReadDirectoryChangesW 监控文件变化

一时失言乱红尘 2023-06-30 07:00 18阅读 0赞

本文测试了ReadDirectoryChangesW 类监控文件变化。

#include<iostream> 
    #include<string>
    #include<Windows.h>
    using namespace std;
    
    string  WStringToString(const std::wstring &wstr);
    void RunWatchFile()
    {
        string watchDirectory = "E:/Test";
        HANDLE hDirectory = CreateFile(watchDirectory.c_str(),
                            GENERIC_READ | GENERIC_WRITE | FILE_LIST_DIRECTORY,
                            FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                            NULL,
                            OPEN_EXISTING,
                            FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
                            NULL);
        if (hDirectory == INVALID_HANDLE_VALUE)
        {
            DWORD dwErr = GetLastError();
            return;
        }
    
        char notify[1024];
        memset(notify, 0, sizeof(notify));
        FILE_NOTIFY_INFORMATION *pNotification = (FILE_NOTIFY_INFORMATION *)notify;
        DWORD bytesReturned = 0;
    
        while (TRUE)
        {
            ZeroMemory(pNotification, sizeof(notify));
    
            auto watchState = ReadDirectoryChangesW(hDirectory,
                &notify,
                sizeof(notify),
                TRUE,   //监控子目录
                FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_LAST_WRITE, 
                (LPDWORD)&bytesReturned,
                NULL,
                NULL);
    
            if (GetLastError() == ERROR_INVALID_FUNCTION)
            {
                cout << "文件监控，系统不支持 " << watchDirectory << endl;
                break;
            }
            else if (watchState == FALSE)
            {
                DWORD dwErr = GetLastError();
                cout << "文件监控，监控失败 " << watchDirectory << dwErr << endl;
                break;
            }
            else if (GetLastError() == ERROR_NOTIFY_ENUM_DIR)
            {
                cout << "文件监控，内存溢出 " << watchDirectory <<endl;
                continue;
            }
            else
            {
                //检测返回的信息
                wstring fileName(pNotification->FileName, pNotification->FileNameLength / sizeof(wchar_t));
                std::string fullFileName = watchDirectory + "/" +  WStringToString(fileName);          
                if (pNotification->Action == FILE_ACTION_ADDED)
                {
                    cout << "文件监控，新增文件 " << fullFileName  << endl;
                }
                else if (pNotification->Action == FILE_ACTION_REMOVED)
                {
                    cout << "文件监控，删除文件 " << fullFileName << endl;
                }
                else if (pNotification->Action == FILE_ACTION_MODIFIED)
                {
                    cout << "文件监控，修改文件 "  << fullFileName << endl;
                }
                else if (pNotification->Action == FILE_ACTION_RENAMED_OLD_NAME)
                {
                    cout << "文件监控，重命名文件 " << fullFileName << endl;
                }
                //PostMessage通知主线程
            }
        }
        CloseHandle(hDirectory);
    }
    
    string  WStringToString(const std::wstring &wstr)
    {
        string result;
        //获取缓冲区大小，并申请空间，缓冲区大小事按字节计算的  
        int len = WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), NULL, 0, NULL, NULL);
        char* buffer = new char[len + 1];
        //宽字节编码转换成多字节编码  
        WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), buffer, len, NULL, NULL);
        buffer[len] = '\0';
        //删除缓冲区并返回值  
        result.append(buffer);
        delete[] buffer;
        return result;
    }
    
    int main()
    {
        RunWatchFile();
        getchar();
        return 0;
    }

上例中监控的目录是“E:\\\\Test”，在此目录下创建txt文件，命名为“log.txt”。

![2020011518000386.png][]

运行结果：

![202001151759465.png][]

[2020011518000386.png]: https://img-blog.csdnimg.cn/2020011518000386.png
[202001151759465.png]: https://img-blog.csdnimg.cn/202001151759465.png