一篇文章带你了解java数据库连接

Class.forName( "com.mysql.cj.jdbc.Driver" );

conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/test_demo?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC" , "root" , "password" );

CREATE TABLE `websites` (

   `id` int (11) NOT NULL AUTO_INCREMENT,

   ` name ` char (20) NOT NULL DEFAULT '' COMMENT '站点名称' ,

   `url` varchar (255) NOT NULL DEFAULT '' ,

   `alexa` int (11) NOT NULL DEFAULT '0' COMMENT 'Alexa 排名' ,

   `country` char (10) NOT NULL DEFAULT '' COMMENT '国家' ,

   PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

INSERT INTO `test_demo`.`websites` (`id`, ` name `, `url`, `alexa`, `country`) VALUES ( '1' , 'Google' , 'https://HdhCmsTestgoogle.cm/' , '1' , 'USA' );

INSERT INTO `test_demo`.`websites` (`id`, ` name `, `url`, `alexa`, `country`) VALUES ( '2' , '淘宝' , 'https://HdhCmsTesttaobao测试数据/' , '13' , 'CN' );

INSERT INTO `test_demo`.`websites` (`id`, ` name `, `url`, `alexa`, `country`) VALUES ( '3' , 'java入门' , 'https://blog.csdn.net/wwwzhouzy/category_11249888.html' , '5892' , '' );

INSERT INTO `test_demo`.`websites` (`id`, ` name `, `url`, `alexa`, `country`) VALUES ( '4' , '微博' , 'http://weibo测试数据/' , '20' , 'CN' );

INSERT INTO `test_demo`.`websites` (`id`, ` name `, `url`, `alexa`, `country`) VALUES ( '5' , 'Facebook' , 'https://HdhCmsTestfacebook测试数据/' , '3' , 'USA' );

package com.zhouzy.base.t11;

import java.sql.*;

public class MysqlTest {

      // MySQL 8.0 以下版本 - JDBC 驱动名及数据库 URL

     static final String JDBC_DRIVER = "com.mysql.jdbc.Driver" ; 

     static final String DB_URL = "jdbc:mysql://localhost:3306/test_demo" ;

     // MySQL 8.0 以上版本 - JDBC 驱动名及数据库 URL

     //static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; 

     //static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC";

     // 数据库的用户名与密码，需要根据自己的设置

     static final String USER = "root" ;

     static final String PASS = "123456" ;

     public static void main(String[] args) {

         Connection conn = null ;

         Statement stmt = null ;

         try {

             // 注册 JDBC 驱动

             Class.forName(JDBC_DRIVER);

             // 打开链接

             System.out.println( "连接数据库..." );

             conn = DriverManager.getConnection(DB_URL,USER,PASS);

             // 执行查询

             System.out.println( " 实例化Statement对象..." );

             stmt = conn.createStatement();

             String sql;

             sql = "SELECT id, name, url FROM websites" ;

             ResultSet rs = stmt.executeQuery(sql);

             // 展开结果集数据库

             while (rs.next()){

                 // 通过字段检索

                 int id  = rs.getInt( "id" );

                 String name = rs.getString( "name" );

                 String url = rs.getString( "url" );

                 // 输出数据

                 System.out.print( "ID: " + id);

                 System.out.print( ", 站点名称: " + name);

                 System.out.print( ", 站点 URL: " + url);

                 System.out.print( "\n" );

             }

             // 完成后关闭

             rs.close();

             stmt.close();

             conn.close();

         } catch (SQLException se){

             // 处理 JDBC 错误

             se.printStackTrace();

         } catch (Exception e){

             // 处理 Class.forName 错误

             e.printStackTrace();

         } finally {

             // 关闭资源

             try {

                 if (stmt!= null ) stmt.close();

             } catch (SQLException se2){

             } // 什么都不做

             try {

                 if (conn!= null ) conn.close();

             } catch (SQLException se){

                 se.printStackTrace();

             }

         }

         System.out.println( "再见!" );

     }

}