C++监听文件件类文件变化

简介：

        使用FindFirstChangeNotificationW监听指定路径文件变化，入参为文件夹路径（不是文件名），WaitForSingleObject等待文件夹变化，读取内部所有文件及其修改时间，只刷新最新修改的。以下基于C++17版本

        类似可以搜索watch4folder、Directory Monitor 2等工具使用

代码：

#include <iostream>
#include <windows.h>
#include <fstream>
#include <unordered_map>
#include <string>

// 记录文件的修改时间
std::unordered_map<std::wstring, FILETIME> lastModifiedTimes;

void watchFile(const std::wstring& directory) {
    // 设置监视路径
    HANDLE hChange = FindFirstChangeNotificationW(
        directory.c_str(),   // 监视目录路径
        FALSE,                // 不递归子目录
        FILE_NOTIFY_CHANGE_LAST_WRITE  // 监听文件修改（最后写入时间）
    );

    if (hChange == INVALID_HANDLE_VALUE) {
        DWORD dwError = GetLastError();
        std::cerr << "Failed to set up the change notification! Error code: " << dwError << std::endl;
        return;
    }

    std::cout << "Watching directory for changes..." << std::endl;

    while (true) {
        // 等待文件夹变化
        DWORD dwWaitStatus = WaitForSingleObject(hChange, INFINITE);

        if (dwWaitStatus == WAIT_OBJECT_0) {
            // 文件夹内某个文件发生了变化
            std::wcout << L"Detected a file change in directory: " << directory << std::endl;

            // 遍历目录中的所有文件
            WIN32_FIND_DATA findFileData;
            HANDLE hFind = FindFirstFile((directory + L"\\*").c_str(), &findFileData);

            if (hFind == INVALID_HANDLE_VALUE) {
                std::cerr << "Failed to find files in the directory!" << std::endl;
                return;
            }

            do {
                if (wcscmp(findFileData.cFileName, L".") != 0 && wcscmp(findFileData.cFileName, L"..") != 0) {
                    std::wstring filePath = directory + L"\\" + findFileData.cFileName;
                    HANDLE hFile = CreateFile(filePath.c_str(), GENERIC_READ, 
                                               FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, 
                                               OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);

                    if (hFile != INVALID_HANDLE_VALUE) {
                        FILETIME ftLastWriteTime;
                        if (GetFileTime(hFile, NULL, NULL, &ftLastWriteTime)) {
                            if (lastModifiedTimes.find(filePath) == lastModifiedTimes.end() || 
                                CompareFileTime(&ftLastWriteTime, &lastModifiedTimes[filePath]) != 0) {
                                lastModifiedTimes[filePath] = ftLastWriteTime;  // 更新文件的修改时间
                                std::wcout << L"File " << filePath << L" has been modified!" << std::endl;

                                // 读取文件内容
                                std::wifstream file(filePath);
                                if (file.is_open()) {
                                    std::wcout << L"File content:\n";
                                    std::wcout << file.rdbuf() << std::endl;
                                } else {
                                    std::cerr << "Failed to open the file!" << std::endl;
                                }
                            }
                        } else {
                            std::cerr << "Failed to get file time for: " << filePath << std::endl;
                        }
                        CloseHandle(hFile);
                    } else {
                        std::cerr << "Failed to open file: " << filePath << std::endl;
                    }
                }
            } while (FindNextFile(hFind, &findFileData) != 0);

            FindClose(hFind);

            // 重新设置通知，以便继续监听
            if (!FindNextChangeNotification(hChange)) {
                std::cerr << "Failed to reset change notification!" << std::endl;
                return;
            }
        } else if (dwWaitStatus == WAIT_FAILED) {
            std::cerr << "Error while waiting for changes!" << std::endl;
            return;
        }
    }

    FindCloseChangeNotification(hChange);
}

int main() {
    std::wstring directoryPath = L"F:\\SteamLibrary\\steamapps\\common\\MonsterHunterRise\\reframework\\data";
    watchFile(directoryPath);  // 开始监听目录
    return 0;
}