java 数据库mysql的连接

代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class ConnectMysql {
    Connection conn;

    //打开数据库连接
    public Connection openDb(){
        try {
            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("数据库驱动加载成功!");
            //！一定下载mysql驱动器
        } catch (ClassNotFoundException e) {
            System.out.println("数据库驱动加载失败!");
            e.printStackTrace();
        }
        try {
            conn= DriverManager.getConnection(
                    //！时区问题，需要在url后面加上“?serverTimezone=UTC ”
                    "jdbc:mysql://localhost:3306/mydb?serverTimezone=UTC",
                    "root","123456"

            );
            System.out.println("数据库服务器连接成功!");
        } catch (SQLException throwables) {
            System.out.println("数据库服务器连接失败!");
            throwables.printStackTrace();
        }
        return conn;

    }

    public void closeDb(){
        if (conn!=null) {
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
}

测试DB：

public class DbTest {
    private static ConnectMysql connectMysql = new ConnectMysql();
    public static void main(String[] args) throws SQLException {

        Connection conn = connectMysql.openDb();

        String strSQL = " select * from hwl_needed ";
        Statement st = conn.createStatement();
        ResultSet rs = st.executeQuery(strSQL);

        while (rs.next()){
            System.out.println(rs.getString(2));
        }

        connectMysql.closeDb();
//节省资源 一定要关闭数据库连接
    }
}

结果↓