java - 如何在java中保持连接

Question

我正在使用 MySQL 开发我的第一个 Java 项目。我有一个函数，每次从数据源取回数据时都会调用该函数。此函数应将新行保存到我的 MySQL 数据库中。请参阅此处的代码:

import java.sql.*;
import java.util.Properties;

/**
 *
 * @author jeffery
 */
public class SaveToMysql {
    // The JDBC Connector Class.
    private static final String dbClassName = "com.mysql.jdbc.Driver";

    private static final String CONNECTION = "jdbc:mysql://localhost/test";

    static public String test(int reqId, String date, double open, double high, double low,
                                        double close, int volume, int count, double WAP, boolean hasGaps){

        if (date.contains("finished")){
            return "finished";
        }


        // Class.forName(xxx) loads the jdbc classes and
        // creates a drivermanager class factory
        try{
            Class.forName(dbClassName);
        }catch ( ClassNotFoundException e ) {
            System.out.println(e);
        }

        // Properties for user and password. Here the user and password are both 'paulr'
        Properties p = new Properties();
        p.put("user","XXXXXXXX");
        p.put("password","XXXXXXXXXXXx");

        // Now try to connect
        Connection conn;
        try{
            conn = DriverManager.getConnection(CONNECTION,p);
        }catch(SQLException e){
            return e.toString();
        }

        PreparedStatement stmt;
        try{
            stmt = conn.prepareStatement("insert into dj_minute_data set symbol = (select ticker from dow_jones_constituents where id = ?), "
                    + "date = str_to_date(?,'%Y%m%d %H:%i:%s')" +
            ", open = ?" +
            ", high = ?" +
            ", low = ?" +
            ", close = ?" +
            ", volume = ?" +
            ", adj_close = ?");
            stmt.setInt(1, reqId);
            stmt.setString(2, date);
            stmt.setDouble(3, open);
            stmt.setDouble(4, high);
            stmt.setDouble(5, low);
            stmt.setDouble(6, close);
            stmt.setDouble(7, volume);
            stmt.setDouble(8, WAP);
        }catch (SQLException e){
            return e.toString();
        }

        try{
            stmt.executeUpdate();
        }catch (SQLException e){
            return e.toString();
        }

        return stmt.toString();
    }

}

如您所见，test 函数在它自己的类中，名为 SaveToMysql。要调用此函数，我将该类导入到另一个类中，并使用以下语法:

msg = SaveToMysql.test(reqId, date, open, high, low, close, volume, count, WAP, hasGaps);

消息然后输出到屏幕。显示错误消息或成功。

该函数可能会在短时间内被快速调用多次。我知道我不应该在每次调用该函数时都重新打开与 MySQL 服务器的连接。我该如何更改它，以便 1 个 MySQL 连接在每次调用该函数时保持打开状态。

谢谢!!

Answer 1

JDBC 网址:jdbc:mysql://:/? connectTimeout=0&socketTimeout=0&autoReconnect=true