在Java中設計貨幣相關的業務邏輯，首先需要了解貨幣的基本概念和屬性。以下是一個簡單的示例，展示了如何創建一個表示貨幣的類，并實現一些基本的貨幣操作。

1. 創建一個表示貨幣的類（Money）：

public class Money {
    private double amount; // 金額
    private String currency; // 貨幣單位，例如：USD, CNY等

    public Money(double amount, String currency) {
        this.amount = amount;
        this.currency = currency;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }

    public String getCurrency() {
        return currency;
    }

    public void setCurrency(String currency) {
        this.currency = currency;
    }
}

2. 為貨幣類添加業務邏輯方法，例如加、減、乘、除等操作：

public class Money {
    // ... 其他代碼

    // 加法操作
    public Money add(Money other) {
        if (!this.currency.equals(other.currency)) {
            throw new IllegalArgumentException("Currencies do not match");
        }
        return new Money(this.amount + other.amount, this.currency);
    }

    // 減法操作
    public Money subtract(Money other) {
        if (!this.currency.equals(other.currency)) {
            throw new IllegalArgumentException("Currencies do not match");
        }
        return new Money(this.amount - other.amount, this.currency);
    }

    // 乘法操作
    public Money multiply(double multiplier) {
        return new Money(this.amount * multiplier, this.currency);
    }

    // 除法操作
    public Money divide(double divisor) {
        if (divisor == 0) {
            throw new IllegalArgumentException("Divisor cannot be zero");
        }
        return new Money(this.amount / divisor, this.currency);
    }
}

3. 使用貨幣類進行業務邏輯操作：

public class Main {
    public static void main(String[] args) {
        Money money1 = new Money(10, "USD");
        Money money2 = new Money(20, "USD");

        Money sum = money1.add(money2);
        System.out.println("Sum: " + sum.getAmount() + " " + sum.getCurrency());

        Money difference = money1.subtract(money2);
        System.out.println("Difference: " + difference.getAmount() + " " + difference.getCurrency());

        Money product = money1.multiply(3);
        System.out.println("Product: " + product.getAmount() + " " + product.getCurrency());

        Money quotient = money1.divide(2);
        System.out.println("Quotient: " + quotient.getAmount() + " " + quotient.getCurrency());
    }
}

這個示例展示了如何創建一個表示貨幣的類，并實現一些基本的貨幣操作。在實際項目中，你可能需要根據業務需求對該類進行擴展，例如添加貨幣轉換功能、格式化輸出等。