Jdbc

package com.jdbcUtils;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
public class JdbcUtils {
    //连接参数
    private static  String user;
    private static  String password;
    private static  String url;
    private static  String driver;
    //用static代码块去初始化
    static{
        try {
            Properties properties=new Properties();
            properties.load(new FileInputStream("src\mysql.properties"));
            user=properties.getProperty("user");
            password=properties.getProperty("password");
            url=properties.getProperty("url");
            driver=properties.getProperty("driver");
        } catch (IOException e) {
            //实际开发中将编译异常转为运行异常，调用者捕获或者默认处理
            throw new RuntimeException(e);
        }
    }
    //连接数据库 返回connection
    public static Connection getConnection(){
        try {
            Class.forName(driver);
            return DriverManager.getConnection(url,user,password);
        } catch (Exception e) {
            //实际开发中将编译异常转为运行异常，调用者捕获或者默认处理
            throw new RuntimeException(e);
        }
    }
    //关闭资源 1.ResultSet PrepareStatement Connection
    //传如null不关闭
    public static  void close(ResultSet rs, Statement statement,Connection connection){
        try {
            if (rs!=null) {
                rs.close();
            }
            if (statement!=null) {
                statement.close();
            }
            if (connection!=null) {
                connection.close();
            }
        } catch (SQLException e) {
            //实际开发中将编译异常转为运行异常，调用者捕获或者默认处理
            throw new RuntimeException(e);
        }
    }
}

JdbcConnect 测试代码

package com.company;
import com.jdbcUtils.JdbcUtils;
import org.junit.jupiter.api.Test;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
import java.util.Scanner;
public class JdbcConnect {
    @Test
    public void connection() throws IOException {
        Connection connection=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
  
        try {
            //获取连结
            connection=JdbcUtils.getConnection();
            //创建sql语句
            String sql="select *from user where name=?";
            //创建执行者对象
           ps=connection.prepareStatement(sql);
            //参数赋值
            ps.setString(1,"大菜鸡");
            //创建结果集对象
            rs=ps.executeQuery();
            //循环遍历输出结果
            while(rs.next()){//rs往后走一行有数据进入循环体
                String name=rs.getString("name");
                String pwd=rs.getString("pwd");
                System.out.println("name:"+name+"pwd:"+pwd);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //关闭连接
            JdbcUtils.close(rs,ps,connection);
        }
    }
}