JAVA实验3：Java-MySQL实现银行转账系统

本文主要是介绍JAVA实验3：Java-MySQL实现银行转账系统，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

运行结果

实验中解决了用户登录时SQL注入问题，提高了系统的安全性
并且关闭了事务自动提交，开启了事务回滚功能，保证了用户资金的安全性

PowerDesigner16.5建模

数据库源码

drop table if exists userlogin;/*==============================================================*/
/* Table: userlogin                                             */
/*==============================================================*/
create table userlogin
(username             varchar(20) not null,password             varchar(20),primary key (username)
);drop table if exists userstate;/*==============================================================*/
/* Table: userstate                                             */
/*==============================================================*/
create table userstate
(username             varchar(20) not null,money                bigint,primary key (username)
);insert into userlogin(username,password) values('zrs','333');
insert into userlogin(username,password) values('llf','222');
insert into userstate(username,money) values('zrs',20000);
insert into userstate(username,money) values('llf',0);

使用的java模块

java源码

Bank主函数入口：

package Bank;import Mysql.Mysql;
import InitUI.InitUI;
import TransfroUI.*;
import UserLogin.UserLogin;
import java.sql.*;
import java.util.Map;public class Bank {public static void main(String[] args){Connection conn = null;PreparedStatement pstmt = null;ResultSet rs = null;try{conn = Mysql.connection("bank");Map<String,String> map = InitUI.initUI();String uname = map.get("username");String pwd = map.get("password");UserLogin.userLogin(uname,pwd,conn);conn.setAutoCommit(false);transfor(uname,conn);conn.commit();}catch(SQLException e){if(conn != null){try{conn.rollback();System.out.println("事务回滚");}catch(Exception a){a.printStackTrace();;}}e.printStackTrace();}catch(Exception e){e.printStackTrace();}finally{Mysql.close(conn,pstmt,rs);}}private static void transfor(String uname,Connection conn) throws SQLException{Map<String,String> trans = TransforUI.transforUI();String tname = trans.get("transforname");String money = trans.get("money");String[] sql = {"update userstate set money = money+? where username = ?;","update userstate set money = money-? where username = ?","select money from userstate where username = ?"};PreparedStatement pstmt_0 = conn.prepareStatement(sql[0]);PreparedStatement pstmt_1 = conn.prepareStatement(sql[1]);PreparedStatement pstmt_2 = conn.prepareStatement(sql[2]);pstmt_0.setString(1,money);pstmt_0.setString(2,tname);pstmt_1.setString(1,money);pstmt_1.setString(2,uname);pstmt_2.setString(1,uname);int count = pstmt_0.executeUpdate();count += pstmt_1.executeUpdate();ResultSet rs = pstmt_2.executeQuery();rs.next();if(count==2 && rs.getInt("money")>=0){System.out.println("转账成功");}else{System.out.println("余额不足");throw new SQLException();}}
}

Mysql封装源码：

package Mysql;import java.sql.*;public class Mysql{private Mysql(){}//注册驱动static{try{Class.forName("com.mysql.cj.jdbc.Driver");}catch(Exception e){e.printStackTrace();}}//连接数据库public static Connection connection(String database_name) throws Exception{return DriverManager.getConnection("jdbc:mysql://localhost:3306/"+database_name,"root","feifei123");}//释放资源public static void close(Connection conn, PreparedStatement pstmt){if(pstmt != null){try{pstmt.close();}catch(SQLException e){e.printStackTrace();}}if(conn != null){try{conn.close();}catch(SQLException e){e.printStackTrace();}}}//重载释放资源方法public static void close(Connection conn,PreparedStatement pstmt,ResultSet rs){if(rs != null){try{rs.close();}catch(SQLException e){e.printStackTrace();}}if(pstmt != null){try{pstmt.close();}catch(SQLException e){e.printStackTrace();}}if(conn != null){try{conn.close();}catch(SQLException e){e.printStackTrace();}}}
}

用户输入模块源码：

package InitUI;import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;public class InitUI {private InitUI(){}public static Map<String, String> initUI() {Map<String,String> map = new HashMap();Scanner s = new Scanner(System.in);System.out.println("请输入用户名：");String username = s.next();System.out.println("请输入密码：");String password = s.next();map.put("username",username);map.put("password",password);return map;}
}

用户登录检测源码：

package UserLogin;import java.sql.*;
import java.sql.SQLException;
import java.util.Map;
import java.util.ResourceBundle;public class UserLogin {private UserLogin(){}public static void userLogin(String username, String password,Connection conn) throws Exception{String sql = "select * from userlogin where username = ? and password = ?;";PreparedStatement pstmt = conn.prepareStatement(sql);pstmt.setString(1,username);pstmt.setString(2,password);ResultSet rs = pstmt.executeQuery();boolean flag = rs.next()==true?true:false;if(flag){System.out.println(username+"欢迎回来");}else{System.out.println("登录失败，请重新登录");Map<String,String> map =InitUI.InitUI.initUI();String uname = map.get("username");String pwd = map.get("password");userLogin(uname,pwd,conn);}}
}

用户转账检测源码：

package TransfroUI;import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;public class TransforUI {private TransforUI(){}public static Map<String, String> transforUI() {Map<String,String> map = new HashMap();Scanner s = new Scanner(System.in);System.out.println("请输入要转账的用户名：");String username = s.next();System.out.println("请输入要转账的金额：");String password = s.next();map.put("transforname",username);map.put("money",password);return map;}
}

这篇关于JAVA实验3：Java-MySQL实现银行转账系统的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！

---