一. 文本文件读写

  • QFile
  • QTextStream | 枚举值 | 描述 | | —- | —- | | QIODevice::ReadOnly | 以只读方式打开 | | QIODevice::WriteOnly | 以只写方式打开 | | QIODevice::ReadWrite | 以读写方式打开 | | QIODevice::Append | 以追加方式加到文件末尾 | | QIODevice::Truncate | 以重写方式打开，原有内容会被删除 | | QIODevice::Text | 在读取时，将行结束符转换成\n；在写入时，将行结束符转成本地格式，如 Win32 是 \r\n |

1. QFile

直接操作，相当于每人一瓶水。

  • 读文件:
  1. #include <QFileDialog>
  2. QString curPath = QCoreApplication::applicationDirPath();
  3. QString title = "打开文件";
  4. QString filter = "文本文件(*.txt);;所有文件(*.*)";
  5. QString fileName = QFileDialog::getOpenFileName(this,
  6.                                                 title,
  7.                                                 curPath,
  8.                                                 filter);
  9. if (fileName.isEmpty()) return;
  11. QFile file(fileName);
  12. if (file.open(QIODevice::ReadOnly|QIODevice::Text)) {
  13.     ui->plainTextEditIODevice->setPlainText(file.readAll());
  14.     file.close();
  15. }
  • 写文件:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString title = "保存文件";
  3. QString filter = "文本文件(*.txt);;所有文件(*.*)";
  4. QString fileName = QFileDialog::getSaveFileName(this,
  5.                                                 title,
  6.                                                 curPath,
  7.                                                 filter);
  8. if (fileName.isEmpty()) return;
  10. QString str = ui->plainTextEditIODevice->toPlainText();
  11. QFile file(fileName);
  12. QByteArray strBytes = str.toUtf8();
  13. if (file.open(QIODevice::WriteOnly|QIODevice::Text)) {
  14.     file.write(strBytes, strBytes.length());
  15. }

2. QTextStream

相当于装个饮水机，所有水都放入饮水机，然后一杯一杯弄，很好的控制

  • 读操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString title = "保存文件";
  3. QString filter = "文本文件(*.txt);;所有文件(*.*)";
  4. QString fileName = QFileDialog::getOpenFileName(this,
  5.                                                 title,
  6.                                                 curPath,
  7.                                                 filter);
  8. if (fileName.isEmpty()) return;
  10. QFile file(fileName);
  11. if (file.open(QIODevice::ReadOnly|QIODevice::Text)) {
  12.     QTextStream stream(&file);
  13. //  ui->plainTextEditTextStream->setPlainText(stream.readAll());
  14.     while (!stream.atEnd()) {
  15.         ui->plainTextEditTextStream->appendPlainText(stream.readLine());
  16.     }
  17.     file.close();
  18. }
  • 写操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString title = "保存文件";
  3. QString filter = "文本文件(*.txt);;所有文件(*.*)";
  4. QString fileName = QFileDialog::getSaveFileName(this,
  5.                                                 title,
  6.                                                 curPath,
  7.                                                 filter);
  8. if (fileName.isEmpty()) return;
  10. QString str = ui->plainTextEditTextStream->toPlainText();
  11. QFile file(fileName);
  12. if (file.open(QIODevice::WriteOnly|QIODevice::Text)) {
  13.     QTextStream stream(&file);
  14.     stream << str;
  15. }

二. 二进制文件读写

  • QFile: 负责文件的 IO 设备接口，即与文件的物理交互。

  • QDataStream: 以数据流的方式读取或写入文件内容

    • Qt 预定义编码
    • 标准编码

1. Qt 预定义编码

  • 写操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString fileName = QFileDialog::getSaveFileName(this,
  3.                                                 "保存文件",
  4.                                                 curPath,
  5.                                                 "Qt预定义编码(*.stm)");
  7. if (fileName.isEmpty()) return;
  9. QFile file(fileName);
  10. if (file.open(QIODevice::WriteOnly|QIODevice::Truncate)) {
  11.     QDataStream stream(&file);
  12.     stream.setVersion(QDataStream::Qt_5_9);
  14.     qint16 rowCount = theModel->rowCount();
  15.     qint16 colCount = theModel->columnCount();
  16.     stream << rowCount;
  17.     stream << colCount;
  19.     for (int i=0; i<colCount; i++)
  20.             stream << theModel->horizontalHeaderItem(i)->text();
  22.     // 数据区域
  23.     qint16 Depth;
  24.     qreal MeasuredDepth, Direction, Offset;
  25.     QString Quality;
  26.     bool Sampled;
  27.     for (int i=0; i<rowCount; i++) {
  28.         Depth = theModel->item(i, 0)->data(Qt::DisplayRole).toInt();
  29.         stream << Depth;
  31.         MeasuredDepth = theModel->item(i, 1)->data(Qt::DisplayRole).toFloat();
  32.         stream << MeasuredDepth;
  34.         Direction = theModel->item(i, 2)->data(Qt::DisplayRole).toFloat();
  35.         stream << Direction;
  37.         Offset = theModel->item(i, 3)->data(Qt::DisplayRole).toFloat();
  38.         stream << Offset;
  40.         Quality = theModel->item(i, 4)->data(Qt::DisplayRole).toString();
  41.         stream << Quality;
  43.         Sampled = (theModel->item(i, 5)->checkState() == Qt::Checked);
  44.         stream << Sampled;
  45.     }
  47.     file.close();
  48. }
  • 读操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString fileName = QFileDialog::getOpenFileName(this,
  3.                                                 "打开文件",
  4.                                                 curPath,
  5.                                                 "Qt预定义编码(*.stm)");
  7. if (fileName.isEmpty()) return;
  9. QFile file(fileName);
  10. if (file.open(QIODevice::ReadOnly)) {
  11.     QDataStream stream(&file);
  12.     stream.setVersion(QDataStream::Qt_5_9);
  14.     qint16 rowCount, coloumnCount;
  15.     stream >> rowCount;
  16.     stream >> coloumnCount;
  17.     resetTable(rowCount);
  19.     QString str;
  20.     for (int i=0; i<coloumnCount; i++)
  21.         stream >> str;
  23.     // 数据区域
  24.     qint16 Depth;
  25.     qreal MeasuredDepth, Direction, Offset;
  26.     QString Quality;
  27.     bool Sampled;
  28.     QStandardItem *item;
  29.     QModelIndex index;
  30.     for (int i=0; i<rowCount; i++) {
  31.         stream >> Depth;
  32.         index = theModel->index(i, 0);
  33.         item = theModel->itemFromIndex(index);
  34.         item->setData(Depth, Qt::DisplayRole);
  36.         stream >> MeasuredDepth;
  37.         index = theModel->index(i, 1);
  38.         item = theModel->itemFromIndex(index);
  39.         item->setData(MeasuredDepth, Qt::DisplayRole);
  41.         stream >> Direction;
  42.         index = theModel->index(i, 2);
  43.         item = theModel->itemFromIndex(index);
  44.         item->setData(Direction, Qt::DisplayRole);
  46.         stream >> Offset;
  47.         index = theModel->index(i, 3);
  48.         item = theModel->itemFromIndex(index);
  49.         item->setData(Offset, Qt::DisplayRole);
  51.         stream >> Quality;
  52.         index = theModel->index(i, 4);
  53.         item = theModel->itemFromIndex(index);
  54.         item->setData(Quality, Qt::DisplayRole);
  56.         stream >> Sampled;
  57.         index = theModel->index(i, 5);
  58.         item = theModel->itemFromIndex(index);
  59.         if (Sampled)
  60.             item->setCheckState(Qt::Checked);
  61.         else
  62.             item->setCheckState(Qt::Unchecked);
  63.     }
  65.     file.close();
  66. }

2. 标准编码

  • 写操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString fileName = QFileDialog::getSaveFileName(this,
  3.                                                 "保存文件",
  4.                                                 curPath,
  5.                                                 "标准编码(*.dat)");
  7. if (fileName.isEmpty()) return;
  9. QFile file(fileName);
  10. if (file.open(QIODevice::WriteOnly|QIODevice::Truncate)) {
  11.     QDataStream stream(&file);
  12.     stream.setByteOrder(QDataStream::LittleEndian);
  14.     qint16 rowCount = theModel->rowCount();
  15.     qint16 colCount = theModel->columnCount();
  16.     stream.writeRawData((char *)&rowCount, sizeof(qint16));
  17.     stream.writeRawData((char *)&colCount, sizeof(qint16));
  19.     QByteArray btArray;
  20.     for (int i=0; i<colCount; i++) {
  21.         QString str = theModel->horizontalHeaderItem(i)->text();
  22.         btArray = str.toUtf8();
  23.         stream.writeBytes(btArray, btArray.length());
  24.     }
  26.     // 数据区域
  27.     qint16 Depth;
  28.     qreal MeasuredDepth, Direction, Offset;
  29.     QString Quality;
  30.     bool Sampled;
  31.     for (int i=0; i<rowCount; i++) {
  32.         qDebug("row: %d", i);
  33.         Depth = theModel->item(i, 0)->data(Qt::DisplayRole).toInt();
  34.         qDebug("Depth: %d", Depth);
  35.         stream.writeRawData((char *)&Depth, sizeof(qint16));
  37.         MeasuredDepth = theModel->item(i, 1)->data(Qt::DisplayRole).toFloat();
  38.         stream.writeRawData((char *)&MeasuredDepth, sizeof(qreal));
  40.         Direction = theModel->item(i, 2)->data(Qt::DisplayRole).toFloat();
  41.         stream.writeRawData((char *)&Direction, sizeof(qreal));
  43.         Offset = theModel->item(i, 3)->data(Qt::DisplayRole).toFloat();
  44.         stream.writeRawData((char *)&Offset, sizeof(qreal));
  46.         Quality = theModel->item(i, 4)->data(Qt::DisplayRole).toString();
  47.         stream.writeBytes(Quality.toUtf8(), Quality.length());
  49.         Sampled = (theModel->item(i, 5)->checkState() == Qt::Checked);
  50.         qint8 yes = 0;
  51.         if (Sampled)
  52.             yes = 1;
  53.         stream.writeRawData((char *)&yes, sizeof(qint8));
  54.     }
  56.     file.close();
  57. }
  • 读操作:
  1. QString curPath = QCoreApplication::applicationDirPath();
  2. QString fileName = QFileDialog::getOpenFileName(this,
  3.                                                 "打开文件",
  4.                                                 curPath,
  5.                                                 "标准编码(*.dat)");
  7. if (fileName.isEmpty()) return;
  9. QFile file(fileName);
  10. if (file.open(QIODevice::ReadOnly)) {
  11.     QDataStream stream(&file);
  12.     stream.setByteOrder(QDataStream::LittleEndian);
  14.     qint16 rowCount, colCount;
  15.     stream.readRawData((char *)&rowCount, sizeof(qint16));
  16.     stream.readRawData((char *)&colCount, sizeof(qint16));
  17.     resetTable(rowCount);
  19.     char *buf;
  20.     uint strlen;
  21.     for (int i=0; i<colCount; i++)
  22.         stream.readBytes(buf, strlen);
  24.     // 数据区域
  25.     qint16 Depth;
  26.     qreal MeasuredDepth, Direction, Offset;
  27.     QString Quality;
  28.     qint8 Sampled;
  29.     QStandardItem *item;
  30.     QModelIndex index;
  31.     for (int i=0; i<rowCount; i++) {
  32.         stream.readRawData((char *)&Depth, sizeof(qint16));
  33.         index = theModel->index(i, 0);
  34.         item = theModel->itemFromIndex(index);
  35.         item->setData(Depth, Qt::DisplayRole);
  37.         stream.readRawData((char *)&MeasuredDepth, sizeof(qreal));
  38.         index = theModel->index(i, 1);
  39.         item = theModel->itemFromIndex(index);
  40.         item->setData(MeasuredDepth, Qt::DisplayRole);
  42.         stream.readRawData((char *)&Direction, sizeof(qreal));
  43.         index = theModel->index(i, 2);
  44.         item = theModel->itemFromIndex(index);
  45.         item->setData(Direction, Qt::DisplayRole);
  47.         stream.readRawData((char *)&Offset, sizeof(qreal));
  48.         index = theModel->index(i, 3);
  49.         item = theModel->itemFromIndex(index);
  50.         item->setData(Offset, Qt::DisplayRole);
  52.         stream.readBytes(buf, strlen);
  53.         Quality = QString::fromLocal8Bit(buf, strlen);
  54.         index = theModel->index(i, 4);
  55.         item = theModel->itemFromIndex(index);
  56.         item->setData(Quality, Qt::DisplayRole);
  58.         stream.readRawData((char *)&Sampled, sizeof(qint8));
  59.         index = theModel->index(i, 5);
  60.         item = theModel->itemFromIndex(index);
  61.         if (Sampled == 1)
  62.             item->setCheckState(Qt::Checked);
  63.         else
  64.             item->setCheckState(Qt::Unchecked);
  65.     }
  67.     file.close();
  68. }