目录结构

 

建立jdbc.properties

user=root
password=123456
url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC
driverClass=com.mysql.cj.jdbc.Driver

导入驱动，connector-java....

创建JDBCUtil.java工具类

package com.geng.util;

import javax.xml.transform.Result;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {
    public static Connection getConnection(){
        Connection conn = null;
        try {
            InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
            Properties pros = new Properties();
            pros.load(is);

            String user = pros.getProperty("user");
            String password = pros.getProperty("password");
            String url = pros.getProperty("url");
            String driverClass = pros.getProperty("driverClass");

            Class.forName(driverClass);

            conn = DriverManager.getConnection(url, user, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }

    public static void closeResource(Connection conn, PreparedStatement ps, ResultSet resultSet){
        try {
            if(resultSet != null)
                resultSet.close();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        try {
            if(ps != null)
                ps.close();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        try {
            if(conn != null)
                conn.close();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }
}

创建查询测试类

package com.geng.query;

import com.geng.bean.Customer;
import com.geng.util.JDBCUtils;
import org.junit.jupiter.api.Test;

import java.sql.*;

public class testQuery {
    @Test
    public void test1(){
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet resultSet = null;
        try {
            conn = JDBCUtils.getConnection();
            String sql = "select id, name, email, birth from customers where id = ?";
            ps = conn.prepareStatement(sql);
            ps.setObject(1, 1);
            resultSet = ps.executeQuery();

            if(resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString(2);
                String email = resultSet.getString(3);
                Date date = resultSet.getDate(4);

                Customer customer = new Customer(id, name, email, date);
                System.out.println(customer);
            }
        } catch (Exception throwables) {
            throwables.printStackTrace();
        } finally {
            JDBCUtils.closeResource(conn, ps, resultSet);
        }
    }
}

 把接收的数据封装成一个对象接收，体现了ORM思想

ORM思想：
一个数据库表对应一个Java类；
一条记录对应一个Java对象；
一个字段对应一个Java类中的属性。

Customer类

package com.geng.bean;

import java.sql.Date;

public class Customer {
    private int id;
    private String name;
    private String email;
    private Date date;

    public Customer() {
    }

    public Customer(int id, String name, String email, Date date) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.date = date;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", date=" + date +
                '}';
    }
}

执行效果：