我想写一个java程序来跟踪银行账户
现在我有以下简单的程序：
public class account
{
private double balance;
private String owner;
public account(double x, String s) { balance=x; owner=s; }
public String owner() { return owner; }
public void withdraw(double a) { balance -= a; }
public void deposit(double a) { balance += a; }
public void printbalance() { System.out.println(balance); }
// main for testing:
public static void main(String[] argv)
{
account a1 = new account(2000,"you boss");
account a2 = new account(1000,"me nerd");
a1.deposit(400);
a2.withdraw(300000); // not enough money!
a2.withdraw(-500000); // trying to cheat!
a1.printbalance();
a2.printbalance();
}//main
} // account
我想使用aspectj向这个程序添加以下内容：
1-我想防止账户提取更多的当前余额，并提取负数。
2-我也希望它能防止存款为负数。
3-我需要添加一个图形界面，(按钮(
4-添加在客户进行交易之前需要输入的密码或密码。
5-跟踪账户上的所有交易(提款和存款(，并在要求时打印一份报告。
我将感谢你的帮助。非常感谢。
privileged aspect newAccount
{
//withdraw (prevent withdraw negative numbers and number greater than the //current balance)
void around(account a, double x) : execution(void account.withdraw(double)) && target(a) && args(x){
if(x > a.balance){
System.out.println("not enough money!");
return;
}else if(x < 0){
System.out.println("trying to cheat!");
return;
}
proceed(a, x);
}
//Deposit: prevent deposit negative number
void around(double x) : execution(void account.deposit(double)) && args(x){
if(x < 0){
System.out.println("trying to deposit negtive money!");
return;
}
proceed(x);
}
after() : execution(public static void *.main(String[])){
account.a3 = new account(3000,"he nerd");
a3.deposit(-100);
a3.printbalance();
}
//To Do: pin secret password
//To Do: Transaction Record
}
我可以看到您仍在学习Java，因为您不知道诸如之类的基本编程约定
- 类名应该以大写字母开头
- 变量、参数和字段应具有可理解的名称，而不是单个字母
您还从特权方面使用直接字段访问，而不是仅为类的字段创建公共getter方法并使用这些方法。toString方法也很有用，因为这样您就可以轻松地打印对象，而无需访问getter和制作自己的输出。
此外，在main方法之后运行的建议是一个很好的实验，但没有多大意义。因为帐户所有者与您的应用程序中的一个帐户所有者同名，所以看起来您似乎想侵入该帐户。我在那里评论了代码，以解释为什么它不能这样工作。
我还重构了你的应用程序类和方面，现在看起来像这样，而不改变功能：
package de.scrum_master.app;
public class Account {
private String owner;
private double balance;
public Account(String owner, double balance) {
this.owner = owner;
this.balance = balance;
}
public void withdraw(double amount) {
balance -= amount;
}
public void deposit(double amount) {
balance += amount;
}
public String getOwner() {
return owner;
}
public double getBalance() {
return balance;
}
@Override
public String toString() {
return "Account[owner=" + owner + ", balance=" + balance + "]";
}
public static void main(String[] argv) {
Account bossAccount = new Account("Boss", 2000);
Account nerdAccount = new Account("Nerd", 1000);
bossAccount.deposit(400);
nerdAccount.withdraw(200);
bossAccount.withdraw(300000); // Cannot withdraw more than account balance
nerdAccount.withdraw(-500000); // Cannot withdraw a negative amount
bossAccount.deposit(-123456); // Cannot deposit a negative amount
System.out.println(bossAccount);
System.out.println(nerdAccount);
}
}
package de.scrum_master.aspect;
import de.scrum_master.app.Account;
public aspect AccountAspect {
// Withdrawal
void around(Account account, double amount) :
execution(void Account.withdraw(double)) &&
target(account) &&
args(amount)
{
if (amount > account.getBalance()) {
System.out.println("Cannot withdraw more than account balance");
return;
}
if (amount < 0) {
System.out.println("Cannot withdraw a negative amount");
return;
}
proceed(account, amount);
}
// Deposit
void around(double amount) :
execution(void Account.deposit(double)) &&
args(amount)
{
if (amount < 0) {
System.out.println("Cannot deposit a negative amount");
return;
}
proceed(amount);
}
// This does not make any sense because
// 1. it happens after the application ends (after leaving main method)
// 2. Even though the account owner is the same as in the main method,
// it does not mean that by creating a new object with the same name
// the "Nerd" can manipulate the original account balance. You have to
// intercept the original Account object and manipulate it directly.
after() : execution(public static void *.main(String[])) {
System.out.println("--- after end of main program ---");
Account account = new Account("Nerd", 3000);
account.deposit(-100);
System.out.println(account);
}
// TODO: PIN secret password
// TODO: transaction record
}
控制台日志将为：
Cannot withdraw more than account balance
Cannot withdraw a negative amount
Cannot deposit a negative amount
Account[owner=Boss, balance=2400.0]
Account[owner=Nerd, balance=800.0]
--- after end of main program ---
Cannot deposit a negative amount
Account[owner=Nerd, balance=3000.0]
我不会为你做家庭作业，但会给你一些提示：
PIN(秘密密码(：
Account类需要一个字段pin，该字段可以在构造函数中设置，并且不应该有公共getter方法，以避免任何人都可以访问PIN。如果赋值要求您不编辑基类，而是通过AOP解决问题，那么您可以使用类型间定义(ITD(来添加一个私有字段和一个公共setter，甚至可以为类添加一个额外的构造函数。接下来，您将添加一条建议，要求用户在首次尝试访问某个帐户的任何事务方法(如deposit和withdraw(时在控制台上输入PIN。在正确输入PIN后，他将能够继续，否则将出现错误消息，交易将被禁止。方面本身可以保留所有Account对象的缓存(临时存储(-可能您想使用Set<Account>-这些对象在运行会话期间已成功通过身份验证，以避免用户必须再次输入同一帐户的PIN。每个账户的交易记录：同样，您可以使用ITD向
Account添加类似List<TransactionRecord>的字段，用空列表初始化它，然后为每次存款或取款添加交易记录。对于概念验证，您也可以保持简单，不创建TransactionRecord辅助类，而只使用List<Double>进行交易，记录存款的正金额和取款的负金额。具有"存款123.45"或"提款67.89"等元素的List<String>也是一种可行的选择。重要的是你的老师能看到正确的方面逻辑。