JDBC连接数据库演示

今天重新学习了JDBC连接数据库，使用的数据库是Oracle，在运行前已经手动建立了一张t_user表，建表信息如下：

create table t_user(
       card_id number(19) primary key,
       password varchar2(6),
       balance number(20,3),
       phone varchar2(12)
);

考虑到手机号不会参加数值运算，所以将其类型设定为varchar

Java方面主要为了将来在实际开发中可能会用到，所以尽可能写的比较完善，用户登录部分和后台插入部分基本已经写好

方法写得比较集中，实际开发中可能会把获取用户输入值的部分单独写在主方法里

查询方法和插入方法也会做成带布尔类型返回值的方法

import java.util.*;
import java.sql.*;

public class User {
    public static void main(String[] args) throws Exception {
//        login();
        add();
        }

    public static void login() throws Exception{

        //0.获取用户输入值
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);
        System.out.println("Please enter card id: ");
        String c = input.next();
        System.out.println("Please enter password: ");
        String p = input.next();

        String pass = new String();

        //1.加载驱动
        Class.forName("oracle.jdbc.OracleDriver");

        //2.获得数据库连接
        String url = "jdbc:oracle:thin:@127.0.0.1:1521:XE";
        String user = "hr";
        String password = "hr";
        Connection conn = DriverManager.getConnection(url,user,password);
        System.out.println(conn);

        //3.准备SQL语句
        String insertSQL = "select * from t_accounts "
                + "where card_id = " + c;
        System.out.println(insertSQL);

        //4.发送SQL语句
        Statement stm = conn.createStatement();//获得发送SQL的对象
        ResultSet rs = stm.executeQuery(insertSQL);//发送查询SQL

        //5.处理ResultSet结果集
        while(rs.next()){
            //循环的指向所有行数据
            String passw = rs.getString("password");
            pass = passw;
        }

        //6.释放资源
        rs.close();
        stm.close();
        conn.close();

        System.out.println(pass);

        //7.判断用户输入值是否正确并作输出
        if(Integer.parseInt(pass) == Integer.parseInt(p))
            System.out.println("Login success");
        else
            System.out.println("Login fail, please try again");
    }

    public static void add() throws Exception{

        //0.获取用户输入值
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);
        System.out.println("Please enter card id: ");
        String c = input.next();
        System.out.println("Please enter password: ");
        String p = input.next();
        System.out.println("Please enter balance: ");
        double b = input.nextDouble();
        System.out.println("Please enter phone: ");
        String ph = input.next();

        //1.加载驱动
        Class.forName("oracle.jdbc.OracleDriver");
        //2.获得数据库连接
        String url = "jdbc:oracle:thin:@127.0.0.1:1521:XE";
        String user = "hr";
        String password = "hr";
        Connection conn = DriverManager.getConnection(url,user,password);
        System.out.println(conn);
        //3.准备SQL语句
        String insertSQL = "insert into t_accounts(card_id, password, balance, phoe) values("+c+", '"+p+"', "+b+", '"+ph+"')";
        //4.发送SQL语句
        Statement stm = conn.createStatement();//获得发送SQL的对象
        int i = stm.executeUpdate(insertSQL);//发送SQl（发送增删改）
        System.out.println(i);

        //5.释放资源
        stm.close();
        conn.close();

        //6.判断修改是否成功
        if(i != 0)
            System.out.println("Add success");
        else
            System.out.println("Add fail");
    }
}

控制台输出：

Please enter card id:
100003
Please enter password:
123456
Please enter balance:
100000
Please enter phone:
13007516785
oracle.jdbc.driver.T4CConnection@6438a396
1
Add success