模板方法模式

一个抽象类，将部分逻辑以具体方法以及构造子的形式实现，然后声明一些抽象方法来迫使子类实现剩余的逻辑。不同的子类可以以不同的方式实现这些抽象方法，从而对剩余的逻辑有不同的实现

 

public abstract class Account {

    protected String accountNumber;

    public Account() {
    }

    public Account(String accountNumber) {
        this.accountNumber = accountNumber;
    }

    /**
     * 模板方法
     */
    public double calculateInterest() {
        double interestRate = doCalculateInterestRate();
        String accountType = doCalculateAccountType();
        double amount = calculateAmount(accountType, accountNumber);
        return amount * interestRate;
    }

    protected abstract double doCalculateInterestRate();

    protected abstract String doCalculateAccountType();

    /**
     * 基本方法
     */
    public double calculateAmount(String accountType, String accountNumber) {
        return 1000.00D;
    }
}

 

 

public class MoneyMarketAccount extends Account {

    @Override
    protected String doCalculateAccountType() {
        return "Money Market";
    }

    @Override
    protected double doCalculateInterestRate() {
        return 0.24D;
    }
}

 

 

public class CDAccount extends Account {

    @Override
    protected String doCalculateAccountType() {
        return "Certificate of Deposite";
    }

    @Override
    protected double doCalculateInterestRate() {
        return 0.35D;
    }
}

 

 

public class Client {

    private static Account acct = null;

    public static void main(String[] args) {
        acct = new MoneyMarketAccount();
        System.out.println(acct.calculateInterest());
        acct = new CDAccount();
        System.out.println(acct.calculateInterest());
    }
}