1、配置pom文件，刷新maven

 <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.48</version>
  </dependency>

2、jdbc.properties文件

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://主机名:端口名/数据库
jdbc.username=用户名
jdbc.password=密码

3、java查询mysql数据库

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;

public class Javatest95 {
    /**
     * 从数据库查询数据
     */
    public static void main(String[] args) {
        //查询语句
        String sql = "select username,job from users where id = ?";
        Properties properties = new Properties();
        try {
            //1、解析配置
            properties.load(new FileInputStream(new File("D:\\workspace_IDEA\\Exceltest\\src\\main\\resources\\jdbc.properties")));
            String url = properties.getProperty("jdbc.url");
            String username = properties.getProperty("jdbc.username");
            String password = properties.getProperty("jdbc.password");
            //2、获取connection连接
            Connection connection = DriverManager.getConnection(url,username,password);
            //3、获取PreparedStatement
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
            //4、设置条件字段值
            preparedStatement.setObject(1,1);
            //5、调用查询方法获取结果集
            ResultSet resultSet = preparedStatement.executeQuery();
            //6、从结果集获取结果数据
            while(resultSet.next()){
                String usernameValue = resultSet.getObject("username").toString();
                String jobValue = resultSet.getObject("job").toString();
                System.out.println("username:" + usernameValue + ", job:" + jobValue);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}