Qt 计算文件（含超大文件）的 md5 值

方法源代码如下：

QString fileMd5(const QString &sourceFilePath) {

    QFile sourceFile(sourceFilePath);
    qint64 fileSize = sourceFile.size();
    const qint64 bufferSize = 10240;

    if (sourceFile.open(QIODevice::ReadOnly)) {
        char buffer[bufferSize];
        int bytesRead;
        int readSize = qMin(fileSize, bufferSize);

        QCryptographicHash hash(QCryptographicHash::Md5);

        while (readSize > 0 && (bytesRead = sourceFile.read(buffer, readSize)) > 0) {
            fileSize -= bytesRead;
            hash.addData(buffer, bytesRead);
            readSize = qMin(fileSize, bufferSize);
        }

        sourceFile.close();
        return QString(hash.result().toHex());
    }
    return QString();
}

包含测试的完整代码如下：

#include 
#include 
#include 
#include 

QString fileMd5(const QString &sourceFilePath) {

    QFile sourceFile(sourceFilePath);
    qint64 fileSize = sourceFile.size();
    const qint64 bufferSize = 10240;

    if (sourceFile.open(QIODevice::ReadOnly)) {
        char buffer[bufferSize];
        int bytesRead;
        int readSize = qMin(fileSize, bufferSize);

        QCryptographicHash hash(QCryptographicHash::Md5);

        while (readSize > 0 && (bytesRead = sourceFile.read(buffer, readSize)) > 0) {
            fileSize -= bytesRead;
            hash.addData(buffer, bytesRead);
            readSize = qMin(fileSize, bufferSize);
        }

        sourceFile.close();
        return QString(hash.result().toHex());
    }
    return QString();
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QString md5("0e40d388359b41334831b898262cfe93"); // 使用 md5sum 命令获取

    QString result = fileMd5("/home/toby/bin/Tools.zip");
    qDebug() << "source MD5: " << md5;
    qDebug() << "result MD5: " << result;
    qDebug() << "is equal: " << (result == md5);
    return a.exec();
}

使用 10.1 GB 超大文件的进行测试

10.1 GB 超大文件

测试结果如下：

测试结果

本文参考链接：
http://www.qtcentre.org/threads/47635-Calculate-MD5-sum-of-a-big-file