# 模板方法(Template Method)

# Intent

定义算法框架,并将一些步骤的实现延迟到子类。

通过模板方法,子类可以重新定义算法的某些步骤,而不用改变算法的结构。

# Class Diagram


# Implementation

冲咖啡和冲茶都有类似的流程,但是某些步骤会有点不一样,要求复用那些相同步骤的代码。


public abstract class CaffeineBeverage {

    final void prepareRecipe() {
        boilWater();
        brew();
        pourInCup();
        addCondiments();
    }

    abstract void brew();

    abstract void addCondiments();

    void boilWater() {
        System.out.println("boilWater");
    }

    void pourInCup() {
        System.out.println("pourInCup");
    }
}
public class Coffee extends CaffeineBeverage {
    @Override
    void brew() {
        System.out.println("Coffee.brew");
    }

    @Override
    void addCondiments() {
        System.out.println("Coffee.addCondiments");
    }
}
public class Tea extends CaffeineBeverage {
    @Override
    void brew() {
        System.out.println("Tea.brew");
    }

    @Override
    void addCondiments() {
        System.out.println("Tea.addCondiments");
    }
}
public class Client {
    public static void main(String[] args) {
        CaffeineBeverage caffeineBeverage = new Coffee();
        caffeineBeverage.prepareRecipe();
        System.out.println("-----------");
        caffeineBeverage = new Tea();
        caffeineBeverage.prepareRecipe();
    }
}
boilWater
Coffee.brew
pourInCup
Coffee.addCondiments
-----------
boilWater
Tea.brew
pourInCup
Tea.addCondiments

# JDK

  • java.util.Collections#sort()
  • java.io.InputStream#skip()
  • java.io.InputStream#read()
  • java.util.AbstractList#indexOf()