个人银行账户管理系统C++转Java（第七章）

第七章
1.此版本和原c++类似，加入了父类Account以及派生的子类CreditAccount和SavingsAccount。
2.java里面也有和c++一样的：？ 的用法。

package ob4;

public class Date {
	//日期类
		private int year;		//年
		private	int month;		//月
		private	int day;		//日
		private	int totalDays;	//该日期是从公元元年1月1日开始的第几天
		
		//存储平年中某个月1日之前有多少天，为便于getMaxDay函数的实现，该数组多出一项
		public	int[] DAYS_BEFORE_MONTH =new int[]{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
		public	void show(){
			System.out.println( getYear()+"-"+getMonth()+"-"+getDay());
		}		//输出当前日期
		public Date(int year, int month, int day){
			this.year=year;
			this.month=month;
			this.day=day;
			if (day <= 0 || day > getMaxDay()) {
				System.out.println( "Invalid date: ");
				show();
				System.out.println();
				System.exit(1);
			}
			int years = year - 1;
			totalDays = years * 365 + years / 4 - years / 100 + years / 400
				+ DAYS_BEFORE_MONTH[month - 1] + day;
			if (isLeapYear() && month > 2) totalDays++;
			
		}//用年、月、日构造日期
		public	int getYear() { return year; }
		public	int getMonth() { return month; }
		public	int getDay() { return day; }
		public	int getMaxDay(){
			if (isLeapYear() && month == 2)
				return 29;
			else
				return DAYS_BEFORE_MONTH[month]- DAYS_BEFORE_MONTH[month - 1];
		} //获得当月有多少天
		public	boolean isLeapYear()  {	//判断当年是否为闰年
				return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
			}
		
			//计算两个日期之间差多少天	
		public	int distance(Date date) {
				return totalDays - date.totalDays;
			}

}

package ob4;

public class Account {//账户类

	private String id;	//帐号
	private double balance;	//余额
	private static double total = 0; //所有账户的总金额
	
		//供派生类调用的构造函数，id为账户
	protected Account(final Date date, final String id)
	{
		this.id=id;
		balance=0;
		date.show();
		System.out.println("\t#" + id + " created");
	}
		//记录一笔帐，date为日期，amount为金额，desc为说明
	protected void record(final Date date, double amount, final String desc)
	{
		amount = Math.floor(amount * 100 + 0.5) / 100;	//保留小数点后两位
		balance += amount;
		total += amount;
		date.show();
		System.out.println( "\t#" + id + "\t" + amount + "\t" + balance + "\t" + desc );
	}
		//报告错误信息
	protected void error(final String msg)
	{
		System.out.println("Error(#" + id + "):" + msg);
	}
	
	public final String getId() { return id; }
	public double getBalance() { return balance; }
	public static double getTotal() { return total; }
		//显示账户信息
	public void show()
	{
		System.out.print(id + "\tBalance: " + balance);//这里不用println，不换行
	}

}

package ob4;

public class Accumulator {//将某个数值按日累加

	private Date lastDate;	//上次变更数值的时期
	private double value;	//数值的当前值
	private double sum;		//数值按日累加之和
	
		//构造函数，date为开始累加的日期，value为初始值
	public Accumulator(final Date date, double value)
	{
		lastDate=date;
		this.value=value;
		sum=0;
	}
		//获得到日期date的累加结果
	public double getSum(final Date date){
			return sum + value * date.distance(lastDate);
		}

		//在date将数值变更为value
	public void change(final Date date, double value) {
			sum = getSum(date);
			lastDate = date;
			this.value = value;
		}

		//初始化，将日期变为date，数值变为value，累加器清零
	public void reset(final  Date date, double value) {
			lastDate = date;
			this.value = value;
			sum = 0;
		}

}


package ob4;

public class CreditAccount extends Account{//信用账户类

	private Accumulator acc;	//辅助计算利息的累加器
	private double credit;		//信用额度
	private double rate;		//欠款的日利率
	private double fee;			//信用卡年费

	private double getDebt() {	//获得欠款额
			double balance = getBalance();
			return (balance < 0 ? balance : 0);
	}
	
		//构造函数
	public CreditAccount(final Date date,final String id, double credit, double rate, double fee)
	{
		super(date, id);
		this.credit=credit;
		this.rate=rate;
		this.fee=fee;
		acc = new Accumulator(date, 0);
		
	}
	public double getCredit() { return credit; }
	public double getRate() { return rate; }
	public double getFee() { return fee; }
	public double getAvailableCredit() {	//获得可用信用
			if (getBalance() < 0) 
				return credit + getBalance();
			else
				return credit;
		}
		//存入现金
	public void deposit(final Date date, double amount,final String desc)
	{
		record(date, amount, desc);
		acc.change(date, getDebt());
	}
		//取出现金
	public void withdraw(final Date date, double amount,final String desc)
	{
		if (amount - getBalance() > credit) {
			error("not enough credit");
		} else {
			record(date, -amount, desc);
			acc.change(date, getDebt());
		}
	}
		//结算利息和年费，每月1日调用一次该函数
	public void settle(final Date date)
	{
		double interest = acc.getSum(date) * rate;
		if (interest != 0)
			record(date, interest, "interest");
		if (date.getMonth() == 1)
			record(date, -fee, "annual fee");
		acc.reset(date, getDebt());
	}
	public void show()
	{
		super.show();
		System.out.println( "\tAvailable credit:" + getAvailableCredit());
	}
}

package ob4;

public class SavingsAccount extends Account {
	//储蓄账户类
	private Accumulator acc;	//辅助计算利息的累加器
	private double rate;		//存款的年利率
	
		//构造函数
	public SavingsAccount(final Date date,final String id, double rate)
	{
		super(date,id);
		this.rate = rate;
		acc=new Accumulator(date,0);
	}
	public double getRate() { return rate; }
		//存入现金
	public void deposit(final Date date, double amount,final String desc)
	{
		record(date, amount, desc);
		acc.change(date, getBalance());
	}
		//取出现金
	public void withdraw(final Date date, double amount,final String desc)
	{
		if (amount > getBalance()) {
			error("not enough money");
		} else {
			record(date, -amount, desc);
			acc.change(date, getBalance());
		}
	}
		//结算利息，每年1月1日调用一次该函数
	public void settle(final Date date)
	{
		double interest = acc.getSum(date) * rate / date.distance(new Date(date.getYear() - 1, 1, 1));	//计算年息
		if (interest != 0)
			record(date, interest, "interest");
		acc.reset(date, getBalance());
	}

}

package ob4;

public class Run {
	public static void main(String[] args) {
		Date date = new Date(2008, 11, 1);	//起始日期
		//建立几个账户
		SavingsAccount sa1 = new SavingsAccount(date, "AAAAA", 0.015);
		sa1.deposit(new Date(2008, 11, 5), 5000, "salary");
		sa1.withdraw(new Date(2008, 12, 5), 500, "happy");
		sa1.settle(new Date(2009, 1, 1));
		System.out.println();
		sa1.show(); System.out.println();
		System.out.println();
		SavingsAccount sa2 = new SavingsAccount(date, "02342342", 0.015);
		CreditAccount ca = new CreditAccount(date, "BBBBB", 10000, 0.0005, 50);
		//11月份的几笔账目
		
		ca.withdraw(new Date(2008, 11, 15), 2000, "buy a cell");
		sa2.deposit(new Date(2008, 11, 25), 10000, "sell stock 0323");
		//结算信用卡
		ca.show();
		ca.withdraw(new Date(2008, 12, 1), 52000, "buy a car");
		ca.settle(new Date(2008, 12, 30));
		ca.settle(new Date(2008, 12, 31));
		ca.settle(new Date(2009, 1, 1));
		//12月份的几笔账目
		ca.show();
		ca.deposit(new Date(2008, 12, 31), 2016, "repay the credit");
		
		//结算所有账户
		
		sa2.settle(new Date(2009, 1, 1));
		ca.settle(new Date(2009, 1, 1));
		//输出各个账户信息
		System.out.println();
		
		sa2.show(); System.out.println();
		ca.show();
		System.out.println();
		System.out.println( "Total: " + Account.getTotal());
	}

}