java idea 连接数据库

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

public class QueryDemo {
	public static void main(String[] args) throws Exception {
		QueryDemo demo = new QueryDemo();
		demo.findAllDept();
	}
	
	//查找所有的部门
	public void findAllDept() throws ClassNotFoundException,SQLException{
		//1.注册数据库驱动
		Class.forName("com.mysql.cj.jdbc.Driver");
		//2.与数据库建立连接
		Connection conn = DriverManager.getConnection(
				"jdbc:mysql://@localhost:3306/oaec","root","root");
		//3.创建用来执行SQL语句的Statement对象
		Statement stmt = conn.createStatement();
		//4.执行SQL语句
		String sql = "select id,name,region_id from s_dept";
		//执行查询：executeQuery(String sql)==>ResultSet，结果集
		//增删改：executeUpdate(String sql)==>int，影响的行数
		ResultSet rs = stmt.executeQuery(sql);
		//5.处理结果集（针对查询）
		while(rs.next()) {
			//一次循环处理一行
			int id = rs.getInt(1);
			String name = rs.getString(2);
			int regionId = rs.getInt(3);
			//展示简单输出
			System.out.println(id+","+name+","+regionId);
		}
		//6.释放资源
		//ResultSet-->Statement-->Connection
		if(rs!=null) {
			rs.close();
		}
		if(stmt!=null) {
			stmt.close();
		}
		if(conn!=null) {
			conn.close();
		}
	}
}