商品浏览系统之DHHelper类的设计

一 实现DBHelper类

 

 

二 数据库脚本

SET FOREIGN_KEY_CHECKS=0;

 

-- ----------------------------

-- Table structure for items

-- ----------------------------

DROP TABLE IF EXISTS `items`;

CREATE TABLE `items` (

  `id` int(11) NOT NULL auto_increment,

  `name` varchar(50) default NULL,

  `city` varchar(50) default NULL,

  `price` int(11) default NULL,

  `number` int(11) default NULL,

  `picture` varchar(500) default NULL,

  PRIMARY KEY  (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;

 

-- ----------------------------

-- Records of items

-- ----------------------------

INSERT INTO `items` VALUES ('1', '沃特篮球鞋', '佛山', '180', '500', '001.jpg');

INSERT INTO `items` VALUES ('2', '安踏运动鞋', '福州', '120', '800', '002.jpg');

INSERT INTO `items` VALUES ('3', '耐克运动鞋', '广州', '500', '1000', '003.jpg');

INSERT INTO `items` VALUES ('4', '阿迪达斯T血衫', '上海', '388', '600', '004.jpg');

INSERT INTO `items` VALUES ('5', '李宁文化衫', '广州', '180', '900', '005.jpg');

INSERT INTO `items` VALUES ('6', '小米3', '北京', '1999', '3000', '006.jpg');

INSERT INTO `items` VALUES ('7', '小米2S', '北京', '1299', '1000', '007.jpg');

INSERT INTO `items` VALUES ('8', 'thinkpad笔记本', '北京', '6999', '500', '008.jpg');

INSERT INTO `items` VALUES ('9', 'dell笔记本', '北京', '3999', '500', '009.jpg');

INSERT INTO `items` VALUES ('10', 'ipad5', '北京', '5999', '500', '010.jpg');

 

三 代码

package util;

import java.sql.Connection;

import java.sql.DriverManager;

public class DBHelper {

   

    private static final String driver = "com.mysql.jdbc.Driver"; //数据库驱动

    //连接数据库的URL地址

    private static final String url="jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=UTF-8";

    private static final String username="root";//数据库的用户名

    private static final String password="waDY820828";//数据库的密码

    

    private static Connection conn=null;

    

    //静态代码块负责加载驱动

    static

    {

        try

        {

            Class.forName(driver);

        }

        catch(Exception ex)

        {

            ex.printStackTrace();

        }

    }

    

    //单例模式返回数据库连接对象

    public static Connection getConnection() throws Exception

    {

        if(conn==null)

        {

            conn = DriverManager.getConnection(url, username, password);

            return conn;

        }

        return conn;

    }

    

    public static void main(String[] args) {

        

        try

        {

           Connection conn = DBHelper.getConnection();

           if(conn!=null)

           {

               System.out.println("数据库连接正常！");

           }

           else

           {

               System.out.println("数据库连接异常！");

           }

        }

        catch(Exception ex)

        {

            ex.printStackTrace();

        }

        

    }

}

 

四 测试结果

 

数据库连接正常！