Qt使用SQLite数据库存储管理图片文件

QString g_connectName = "Mysql_connection";

bool MainWindow::createDatabase()
{
    //检测已连接的方式 - 自定义连接名
    if(QSqlDatabase::contains(g_connectName))
    {
        m_Projdb = QSqlDatabase::database(g_connectName);
    }
    else
    {
        m_Projdb = QSqlDatabase::aDDDatabase("QSQLITE",g_connectName);

        //设置数据库路径
        QString sDir = QApplication::applicationDirPath();
        QString sDataPath = sDir + "/mysql.db";
        m_Projdb.setDatabaseName(sDataPath);
    }

    //打开数据库
    if(!m_Projdb.open())
    {
        QMessageBox::infORMation(this,"提示","数据库创建失败，无法打开!");
        return false;
    }

	// 创建表格
    createImageTable();

    //关闭数据库
    m_Projdb.close();

    return true;
}

bool MainWindow::createImageTable()
{
     …………………………
     
    //如果不存在则创建my_table表,id自增,name唯一
    const QString cmdSql = R"(
                           CREATE TABLE IF NOT EXISTS image_table (
                           id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
                           imagename TEXT NOT NULL,
                           type CHAR(50) NOT NULL,
                           notes TEXT,
                           imagedata BLOB NOT NULL
                           );)";

    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作
    QSqlQuery myQuery(m_Projdb);

    if(!myQuery.exec(cmdSql))
    {
        QString sError = myQuery.lastError().text();
        sError = "数据库表格插入数据失败:" + sError;
        QMessageBox::information(this,"提示",sError);
        m_Projdb.close();
        return false;
    }

     …………………………
     

    return true;
}

void MainWindow::on_pushBtn_add_clicked()
{
    QString strImag = ui->lineEdit_file->text();
    QFileInfo fileInfo(strImag);
    ………………
    QString sName = fileInfo.fileName();
    QString sType = fileInfo.suffix();
    QString strNote = ui->plainTextEdit_add->toPlainText();

    if(ImageFileExist(sName))
    {
        QMessageBox::information(this,"提示","图片文件已经存在!");
        return;
    }

	//将数据转换为QByteArray类型存储到数据库中
    QFile* pFile = new QFile(strImag);
    pFile->open(QIODevice::ReadOnly);
    
    QByteArray imageData = pFile->readAll();
    pFile->fileName();
    pFile->close();
    if(!m_Projdb.open())
    {
        QMessageBox::information(this,"提示","数据库无法打开!");
        return;
    }
    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作
    QSqlQuery myQuery(m_Projdb);
    QString cmdSql = "insert into image_table(imagename,type,notes,imagedata) values( '%1','%2','%3',:imagedata)";
    cmdSql = QString(cmdSql).arg(sName).arg(sType).arg(strNote);
    qDebug() << cmdSql;
    myQuery.prepare(cmdSql);
    myQuery.bindValue(":imagedata",imageData);
    if(!myQuery.exec())
    {
        QString sError = myQuery.lastError().text();
        sError = "数据库表格插入数据失败:" + sError;
        QMessageBox::information(this,"提示",sError);
        m_Projdb.close();
        return;
    }

    QMessageBox::information(this,"提示","添加成功!");

    m_Projdb.close();

    // 刷新界面
    …………………………
}

void MainWindow::on_pushBtn_del_clicked()
{
    …………………………
    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作
    QSqlQuery myQuery(m_Projdb);
    QString cmdSql = "DELETE from image_table where imagename = '%1'";
    cmdSql = QString(cmdSql).arg(sFileName);

    qDebug() << cmdSql;

    if(!myQuery.exec(cmdSql))
    {
        QString sError = myQuery.lastError().text();
        sError = "数据库表格删除数据失败:" + sError;
        QMessageBox::information(this,"提示",sError);
        m_Projdb.close();
        return;
    }
    …………………………
    // 刷新界面
    ………………………………
}

void MainWindow::on_pushBtn_modify_clicked()
{
    ……………………
    
    QString sNote = dlg.GetNoteString();
    QSqlQuery myQuery(m_Projdb);
    QString cmdSql = "UPDATE image_table SET notes = '%2' where imagename = '%1'";
    cmdSql = QString(cmdSql).arg(sFileName).arg(sNote);

    …………………………

    // 刷新界面
    …………………………
}

void MainWindow::on_pushBtn_preview_clicked()
{
     ………………………………
    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作
    QSqlQuery myQuery(m_Projdb);
    QString cmdSql = "select * from image_table where imagename = '%1'";
    cmdSql = QString(cmdSql).arg(sFileName);

    qDebug() << cmdSql;

    if(!myQuery.exec(cmdSql))
    {
        QString sError = myQuery.lastError().text();
        sError = "数据库表格查询数据失败:" + sError;
        QMessageBox::information(this,"提示",sError);
        m_Projdb.close();
        return;
    }

    while (myQuery.next())
    {
        QString strFileName = myQuery.value(1).toString();
        QString strFileType = myQuery.value(2).toString();
        QString strNote = myQuery.value(3).toString();

        QByteArray bytes = myQuery.value(4).toByteArray();
        QBuffer buffer(&bytes);
        buffer.open(QIODevice::ReadOnly);
        QImageReader reader(&buffer,strFileType.toLatin1());
        QImage img = reader.read();
        img.save(strFileName);
        break;
    }

    m_Projdb.close();
}

bool MainWindow::GetAllImageRecord()
{
     ………………………………
    
    // 查询表格数据
    const QString cmdSql = R"(SELECT * FROM image_table;)";

    //QSqlQuery构造前，需要db已打开并连接;未指定db或者db无效时使用默认连接进行操作
    QSqlQuery myQuery(m_Projdb);
    if(!myQuery.exec(cmdSql))
    {
        QString sError = myQuery.lastError().text();
        sError = "数据库表格插入数据失败:" + sError;
        QMessageBox::information(this,"提示",sError);
        m_Projdb.close();
        return false;
    }

    while (myQuery.next())
    {
        QString sFileName, sFileType,sNotes;

        for (int i = 0; i < myQuery.record().count(); i++)
        {
            QString strFieldName = myQuery.record().fieldName(i);
            QVariant value = myQuery.record().value(i);
            if(strFieldName == "imagename")
            {
                QString strValue = value.toString();
                sFileName = strValue;
            }
            if(strFieldName == "type")
            {
                QString strValue = value.toString();
                sFileType = strValue;
            }
            if(strFieldName == "notes")
            {
                QString strValue = value.toString();
                sNotes = strValue;
            }
        }

		if (!sFileName.isEmpty() && !sFileType.isEmpty())
		{
			FileInfo fileInfo;
			fileInfo.sName = sFileName;
			fileInfo.sType = sFileType;
            fileInfo.sNotes = sNotes;
			m_vecImageFile.push_back(fileInfo);
		}
    }

   …………………………
   
}