java中mysql实现JDBC连接

一.在mysql控制台创建一个名为demojdbc的数据库

SQL语句：

       create database demojdbc;

       use demojdbc;

       create table user(username varchar(15),password varchar(20));

       insert into user values('user','123456');

查看输入是否正确

mysql> create database demojdbc;

Query OK, 1 row affected (0.00 sec)

 

mysql> use demojdbc;

Database changed

mysql> create table user(username varchar(15),password varchar(20));

Query OK, 0 rows affected (0.11 sec)

 

mysql> insert into user values('user','123456');

Query OK, 1 row affected (0.00 sec)

 

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| demojdbc           |

| mysql              |

| performance_schema |

| test               |

+--------------------+

5 rows in set (0.00 sec)

 

mysql> use demojdbc

Database changed

mysql> show tables;

+--------------------+

| Tables_in_demojdbc |

+--------------------+

| user               |

+--------------------+

1 row in set (0.00 sec)

 

mysql> desc user

    -> ;

+----------+-------------+------+-----+---------+-------+

| Field    | Type        | Null | Key | Default | Extra |

+----------+-------------+------+-----+---------+-------+

| username | varchar(15) | YES  |     | NULL    |       |

| password | varchar(20) | YES  |     | NULL    |       |

+----------+-------------+------+-----+---------+-------+

2 rows in set (0.29 sec)

出现以上表格为已正确创建表格。

二.创建一个Java项目或Java web项目

package com.demo;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class TestJDBC {

   static Connection conn = null;

   public static Connection getConnectionByJDBC(){

   try {

   //1.加载mysql的数据驱动

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

} catch (Exception e) {

// TODO: handle exception

System.out.println("装载驱动包出现异常！");

e.printStackTrace();

}   

   try {

   //2.建立jdbc连接，通过drivermanager类创建数据库连接对象Connection

conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbcdemo", "root","");//URL=协议名+IP地址(域名)+端口+数据库名称；用户名和密码

} catch (Exception e) {

// TODO: handle exception

System.out.println("链接数据库发生异常！");

e.printStackTrace();

}

return conn;

   }

 

  public static void test(){

  String sql ="select * from user";

  getConnectionByJDBC();  

  try {

  //3.创建statement对象，用来执行静态的SQL语句并返回它所生成的结果对像

Statement stmt = conn.createStatement();

//4.执行SQL语句，也可用通过execuUpdate()方法进行插入和删除等操作

ResultSet rs = stmt.executeQuery(sql);

while(rs.next()){

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

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

System.out.println("用户名："+username+"  密码是："+password);

}

} catch (SQLException e) {

// TODO Auto-generated catch block

System.out.println(e.getMessage());

e.printStackTrace();

}finally{

//5.用.close()关闭数据库连接，关闭连接时避免异常发生时在try语句块关闭没有执行

try {

if (conn != null)

conn.close();

} catch (Exception e2) {

// TODO: handle exception

System.out.println(e2.getMessage());

e2.printStackTrace();

}

}

  }

public static void main(String[] args){

  TestJDBC testjdbc = new TestJDBC();

  testjdbc.test();

  }

}

}