/* 方法1 */
    QFile theFile(fileNamePath);
    theFile.open(QIODevice::ReadOnly);
    QByteArray ba = QCryptographicHash::hash(theFile.readAll(), QCryptographicHash::Md5);
    theFile.close();
    qDebug() << ba.toHex().constData();
/* 方法2 */
/*
*   获取文件md5值
*/
QByteArray MainWindow::getFileMd5(QString filePath)
{
    QFile localFile(filePath);
 
    if (!localFile.open(QFile::ReadOnly))
    {
        qDebug() << "file open error.";
        return 0;
    }
 
    QCryptographicHash ch(QCryptographicHash::Md5);
 
    quint64 totalBytes = 0;
    quint64 bytesWritten = 0;
    quint64 bytesToWrite = 0;
    quint64 loadSize = 1024 * 4;
    QByteArray buf;
 
    totalBytes = localFile.size();
    bytesToWrite = totalBytes;
 
    while (1)
    {
        if(bytesToWrite > 0)
        {
            buf = localFile.read(qMin(bytesToWrite, loadSize));
            ch.addData(buf);
            bytesWritten += buf.length();
            bytesToWrite -= buf.length();
            buf.resize(0);
        }
        else
        {
            break;
        }
 
        if(bytesWritten == totalBytes)
        {
            break;
        }
    }
 
    localFile.close();
    QByteArray md5 = ch.result();
 
    return md5;
}

Qt 计算文件（含超大文件）的 md5 值 

//大文件MD5
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 <QCoreApplication>
#include <QCryptographicHash>
#include <QFile>
#include <QDebug>

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

QT 获取文件MD5值_MD5

10.1 GB 超大文件

测试结果如下：

QT 获取文件MD5值_Qt_02