我导的包是，mysql-connector-java-8.0.11，sql版本是8.0.16，数据库/数据表：lucy/imooc

package com.imooc.demo1;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
import   com.mysql.cj.jdbc.Driver;

public class demo1 {
 
 @Test
 public void test() {
  try {
   DriverManager.registerDriver(new Driver());
   Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/lucy", "root", "root");
   
   String sql="select * from imooc";
   
   Statement stmt=conn.createStatement();
   
   ResultSet resultSet=stmt.executeQuery(sql);
   
   while(resultSet.next()) {
    String id=resultSet.getString(1);
    String username=resultSet.getString(2);
    String password=resultSet.getString(3);
    String name=resultSet.getString(4);
    
    System.out.println(id+"  "+username+"  "+password+"  "+name);
   }
   
   resultSet.close();
   stmt.close();
   conn.close();
   
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
  
 }
}