c++ - 只有一个连接到数据库和使用函数，C++

Question

我有一个连接 MySQL 数据库的类。这个类有 4 个方法。 (插入、getResults 等)我不想在每个方法中都创建数据库连接。所以当我们创建这个对象时我想要一个 init() 。我的问题的连接池解决方案吗？我该如何解决？

有 4 个这样的方法:

bool DataAccessObject::getResults(short int data, std::vector<FaceRecord>* rec)
{
//    DataAccessObject *temp = new DataAccessObject();

    bool ret = false;

    try{
        sql::Driver *driver;
        sql::Connection *con;
        sql::Statement *stmt;
        sql::ResultSet *res;
        sql::PreparedStatement *prepStmt;

        /* Create a connection */
        driver = get_driver_instance();
        con = driver->connect("tcp://127.0.0.1:3306", "root", "root");

        /* Connect to the MySQL test database */
        con->setSchema("test");

        std::stringstream s;
        s << "SELECT * FROM Amts WHERE "<< data <<" = "<< data <<"";

        prepStmt = con->prepareStatement (s.str());
        res = prepStmt->executeQuery();

        while(res->next()){
            tempFR.uuId = res->getInt64("uuId");
            tempFR.cameraNo = res->getInt("cameraNo");
            tempFR.age = res->getInt("age");
            tempFR.gender = res->getInt("gender");
            tempFR.time = res->getString("time");
            tempFR.image = res->getString("image");
            rec->push_back(tempFR);
        }


        //return true;
        ret = true;
    }

    catch (sql::SQLException &e)
    {

        std::cout << "# ERR: SQLException in " << __FILE__;
        std::cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << std::endl;
        std::cout << "# ERR: " << e.what();
        std::cout << " (MySQL error code: " << e.getErrorCode();
        std::cout << ", SQLState: " << e.getSQLState() << " )" << std::endl;

    }

    return ret;

}

Answer 1

您可以使用 C++ Singleton design pattern这样您的 init 在您创建它时只会被调用一次。