C++如何实现带进度条的文件复制 进度回调函数设计

#include <iostream>
#include <fstream>
#include <string>
#include <stdexcept>

// 定义一个回调函数类型，用于报告复制进度
typedef void (*ProgressCallback)(double progress);

// 文件复制函数，带进度回调
bool copyFileWithProgress(const std::string& sourcePath, const std::string& destinationPath, ProgressCallback callback) {
    std::ifstream source(sourcePath, std::ios::binary);
    std::ofstream destination(destinationPath, std::ios::binary);

    if (!source.is_open()) {
        std::cerr << "无法打开源文件: " << sourcePath << std::endl;
        return false;
    }

    if (!destination.is_open()) {
        std::cerr << "无法打开目标文件: " << destinationPath << std::endl;
        source.close();
        return false;
    }

    // 获取源文件大小
    source.seekg(0, std::ios::end);
    long long fileSize = source.tellg();
    source.seekg(0, std::ios::beg);

    // 缓冲区大小
    const int bufferSize = 4096;
    char buffer[bufferSize];
    long long bytesCopied = 0;

    while (source.read(buffer, bufferSize) || source.gcount() > 0) {
        // 写入目标文件
        destination.write(buffer, source.gcount());
        if (destination.fail()) {
            std::cerr << "写入目标文件失败" << std::endl;
            source.close();
            destination.close();
            return false;
        }

        bytesCopied += source.gcount();

        // 计算进度
        double progress = static_cast<double>(bytesCopied) / fileSize;

        // 调用回调函数报告进度
        if (callback) {
            callback(progress);
        }
    }

    source.close();
    destination.close();
    return true;
}

// 示例回调函数，用于在控制台输出进度
void consoleProgressCallback(double progress) {
    std::cout << "复制进度: " << (progress * 100) << "%" << std::endl;
}

int main() {
    std::string sourceFile = "source.txt"; // 替换为你的源文件路径
    std::string destinationFile = "destination.txt"; // 替换为你的目标文件路径

    // 创建一个示例的源文件
    std::ofstream tempFile(sourceFile);
    for (int i = 0; i < 1000000; ++i) {
        tempFile << "This is a line of text.\n";
    }
    tempFile.close();

    bool success = copyFileWithProgress(sourceFile, destinationFile, consoleProgressCallback);

    if (success) {
        std::cout << "文件复制成功！" << std::endl;
    } else {
        std::cout << "文件复制失败！" << std::endl;
    }

    return 0;
}