Java 中的迷你银行应用
原文:https://www . geesforgeks . org/mini-banking-application-in-Java/
在任何银行交易中，都有几方参与处理交易，如商人、银行、收款人等。因此，事务可能会失败或被拒绝的原因有很多，所以为了用 Java 处理事务，有一个 JDBC (Java 数据库连接)，它为我们提供了一个连接、执行和从任何数据库获取数据的应用编程接口。它提供了 Java 语言数据库连接标准。它用于编写访问数据库所需的程序。
JDBC 的事务为我们提供了一个特性，它将完整的 SQL 语句视为一个单元，然后执行一次，如果任何语句失败，整个事务都会失败。要使用事务，我们必须设置设置自动提交(false)；手动，一旦所有语句成功执行，将需要在数据库的 commit() 方法中进行更改。
在这个迷你银行应用程序中，为了处理交易，我们使用 JDBC 交易使交易一致。该应用程序为用户提供菜单驱动的控制台界面，使用该界面，用户可以执行创建帐户、登录、查看余额和向其他客户转账等功能。
软件先决条件:
- 关系型数据库
- 黯然失色
MySQL:
MySQL 是一个功能齐全的关系数据库管理系统(RDBMS)。MySQL 是一个免费的开源关系数据库管理系统，它使用结构化查询语言(SQL)，这是在数据库中添加、访问和处理数据的最流行的语言。MySQL 以其速度、可靠性和灵活性而闻名。
Eclipse:
Eclipse 是一个开发和调试(主要)Java 代码的 IDE(交互式开发环境)。它包含一个基本工作空间和一个用于定制环境的可扩展插件系统。
数据库设置:
步骤 1: 创建数据库名称库
步骤 2: 创建表名客户
// Create a database
CREATE DATABASE BANK;
// Create table
CREATE TABLE `customer` (
`ac_no` int NOT NULL AUTO_INCREMENT,
`cname` varchar(45) DEFAULT NULL,
`balance` varchar(45) DEFAULT NULL,
`pass_code` int DEFAULT NULL,
PRIMARY KEY (`ac_no`),
UNIQUE KEY `cname_UNIQUE` (`cname`)
) ;
Eclipse 项目设置:
- 创建新项目
- 创建包名银行
文件配置
文件配置
在银行包中创建一个连接类
步骤 1: 包含 MySQL 的 JDBC 驱动程序
// register jdbc Driver
String mysqlJDBCDriver = "com.mysql.cj.jdbc.Driver";
Class.forName(mysqlJDBCDriver);
步骤 2: 使用 MySQL 用户名和密码创建连接类
// Create Connection
String url = "jdbc:mysql://localhost:3306/mydata";
String user = "root";
String pass = "123";
con = DriverManager.getConnection(url, user, pass);
> > connection.java
Java 语言(一种计算机语言，尤用于创建网站)
package banking;
import java.sql.Connection;
import java.sql.DriverManager;
// Global connection Class
public class connection {
static Connection con; // Global Connection Object
public static Connection getConnection()
{
try {
String mysqlJDBCDriver
= "com.mysql.cj.jdbc.Driver"; //jdbc driver
String url
= "jdbc:mysql://localhost:3306/mydata"; //mysql url
String user = "root"; //mysql username
String pass = "Pritesh4@"; //mysql passcode
Class.forName(mysqlJDBCDriver);
con = DriverManager.getConnection(url, user,
pass);
}
catch (Exception e) {
System.out.println("Connection Failed!");
}
return con;
}
}
目的:这个类使用连接对象返回一个全局数据库连接，所有的命令都将被执行。
注意:在银行包中创建银行管理类
> > bankmanagment.java
Java 语言(一种计算机语言，尤用于创建网站)
package banking;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLIntegrityConstraintViolationException;
import java.sql.Statement;
public class bankManagement { // these class provides all
// bank method
private static final int NULL = 0;
static Connection con = connection.getConnection();
static String sql = "";
public static boolean
createAccount(String name,
int passCode) // create account function
{
try {
// validation
if (name == "" || passCode == NULL) {
System.out.println("All Field Required!");
return false;
}
// query
Statement st = con.createStatement();
sql = "INSERT INTO customer(cname,balance,pass_code) values('"
+ name + "',1000," + passCode + ")";
// Execution
if (st.executeUpdate(sql) == 1) {
System.out.println(name
+ ", Now You Login!");
return true;
}
// return
}
catch (SQLIntegrityConstraintViolationException e) {
System.out.println("Username Not Available!");
}
catch (Exception e) {
e.printStackTrace();
}
return false;
}
public static boolean
loginAccount(String name, int passCode) // login method
{
try {
// validation
if (name == "" || passCode == NULL) {
System.out.println("All Field Required!");
return false;
}
// query
sql = "select * from customer where cname='"
+ name + "' and pass_code=" + passCode;
PreparedStatement st
= con.prepareStatement(sql);
ResultSet rs = st.executeQuery();
// Execution
BufferedReader sc = new BufferedReader(
new InputStreamReader(System.in));
if (rs.next()) {
// after login menu driven interface method
int ch = 5;
int amt = 0;
int senderAc = rs.getInt("ac_no");
;
int receiveAc;
while (true) {
try {
System.out.println(
"Hallo, "
+ rs.getString("cname"));
System.out.println(
"1)Transfer Money");
System.out.println("2)View Balance");
System.out.println("5)LogOut");
System.out.print("Enter Choice:");
ch = Integer.parseInt(
sc.readLine());
if (ch == 1) {
System.out.print(
"Enter Receiver A/c No:");
receiveAc = Integer.parseInt(
sc.readLine());
System.out.print(
"Enter Amount:");
amt = Integer.parseInt(
sc.readLine());
if (bankManagement
.transferMoney(
senderAc, receiveAc,
amt)) {
System.out.println(
"MSG : Money Sent Successfully!\n");
}
else {
System.out.println(
"ERR : Failed!\n");
}
}
else if (ch == 2) {
bankManagement.getBalance(
senderAc);
}
else if (ch == 5) {
break;
}
else {
System.out.println(
"Err : Enter Valid input!\n");
}
}
catch (Exception e) {
e.printStackTrace();
}
}
}
else {
return false;
}
// return
return true;
}
catch (SQLIntegrityConstraintViolationException e) {
System.out.println("Username Not Available!");
}
catch (Exception e) {
e.printStackTrace();
}
return false;
}
public static void
getBalance(int acNo) // fetch balance method
{
try {
// query
sql = "select * from customer where ac_no="
+ acNo;
PreparedStatement st
= con.prepareStatement(sql);
ResultSet rs = st.executeQuery(sql);
System.out.println(
"-----------------------------------------------------------");
System.out.printf("%12s %10s %10s\n",
"Account No", "Name",
"Balance");
// Execution
while (rs.next()) {
System.out.printf("%12d %10s %10d.00\n",
rs.getInt("ac_no"),
rs.getString("cname"),
rs.getInt("balance"));
}
System.out.println(
"-----------------------------------------------------------\n");
}
catch (Exception e) {
e.printStackTrace();
}
}
public static boolean transferMoney(int sender_ac,
int reveiver_ac,
int amount)
throws SQLException // transfer money method
{
// validation
if (reveiver_ac == NULL || amount == NULL) {
System.out.println("All Field Required!");
return false;
}
try {
con.setAutoCommit(false);
sql = "select * from customer where ac_no="
+ sender_ac;
PreparedStatement ps
= con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
if (rs.getInt("balance") < amount) {
System.out.println(
"Insufficient Balance!");
return false;
}
}
Statement st = con.createStatement();
// debit
con.setSavepoint();
sql = "update customer set balance=balance-"
+ amount + " where ac_no=" + sender_ac;
if (st.executeUpdate(sql) == 1) {
System.out.println("Amount Debited!");
}
// credit
sql = "update customer set balance=balance+"
+ amount + " where ac_no=" + reveiver_ac;
st.executeUpdate(sql);
con.commit();
return true;
}
catch (Exception e) {
e.printStackTrace();
con.rollback();
}
// return
return false;
}
}
目的:本课程将提供银行管理的所有方法，如转账、查看余额、创建账户和登录。
注意:在银行套餐中创建用户菜单类(bank.java)。
> > bank.java
Java 语言(一种计算机语言，尤用于创建网站)
package banking;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class bank {
public static void main(String args[]) //main class of bank
throws IOException
{
BufferedReader sc = new BufferedReader(
new InputStreamReader(System.in));
String name = "";
int pass_code;
int ac_no;
int ch;
while (true) {
System.out.println(
"\n ->|| Welcome to InBank ||<- \n");
System.out.println("1)Create Account");
System.out.println("2)Login Account");
try {
System.out.print("\n Enter Input:"); //user input
ch = Integer.parseInt(sc.readLine());
switch (ch) {
case 1:
try {
System.out.print(
"Enter Unique UserName:");
name = sc.readLine();
System.out.print(
"Enter New Password:");
pass_code = Integer.parseInt(
sc.readLine());
if (bankManagement.createAccount(
name, pass_code)) {
System.out.println(
"MSG : Account Created Successfully!\n");
}
else {
System.out.println(
"ERR : Account Creation Failed!\n");
}
}
catch (Exception e) {
System.out.println(
" ERR : Enter Valid Data::Insertion Failed!\n");
}
break;
case 2:
try {
System.out.print(
"Enter UserName:");
name = sc.readLine();
System.out.print(
"Enter Password:");
pass_code = Integer.parseInt(
sc.readLine());
if (bankManagement.loginAccount(
name, pass_code)) {
System.out.println(
"MSG : Logout Successfully!\n");
}
else {
System.out.println(
"ERR : login Failed!\n");
}
}
catch (Exception e) {
System.out.println(
" ERR : Enter Valid Data::Login Failed!\n");
}
break;
default:
System.out.println("Invalid Entry!\n");
}
if (ch == 5) {
System.out.println(
"Exited Successfully!\n\n Thank You :)");
break;
}
}
catch (Exception e) {
System.out.println("Enter Valid Entry!");
}
}
sc.close();
}
}
输出:该类为客户提供了菜单驱动的界面，客户可以在此创建账户、登录账户、转账等。
登录:
->|| Welcome to InBank ||<-
1)Create Account
2)Login Account
Enter Input:2
Enter UserName:pritesh
Enter Password:123
查看余额:
Enter UserName:pritesh
Enter Password:123
Hallo, pritesh
1)Transfer Money
2)View Balance
5)LogOut
Enter Choice:2
-----------------------------------------------------------
Account No Name Balance
112 pritesh 0.00
-----------------------------------------------------------
转账:
Hallo, pritesh
1)Transfer Money
2)View Balance
5)LogOut
Enter Choice:1
Enter Receiver A/c No:110
Enter Amount:5000
Insufficient Balance!
ERR : Failed!
注销:
Hallo, pritesh
1)Transfer Money
2)View Balance
5)LogOut
Enter Choice:5
MSG : Logout Successfully!
安慰
版权属于：月萌API www.moonapi.com，转载请注明出处
