Head First设计模式-模板方法模式
一、整体代码
CaffeineBeverageWithHook.java
public abstract class CaffeineBeverageWithHook { void prepareRecipe() { boilWater(); brew(); pourInCup(); if (customerWantsCondiments()) { addCondiments(); } } abstract void brew(); abstract void addCondiments(); void boilWater() { System.out.println("Boiling water"); } void pourInCup() { System.out.println("Pouring into cup"); } boolean customerWantsCondiments() { return true; } }
CoffeeWithHook.java
import java.io.*; public class CoffeeWithHook extends CaffeineBeverageWithHook { public void brew() { System.out.println("Dripping Coffee through filter"); } public void addCondiments() { System.out.println("Adding Sugar and Milk"); } public boolean customerWantsCondiments() { String answer = getUserInput(); if (answer.toLowerCase().startsWith("y")) { return true; } else { return false; } } private String getUserInput() { String answer = null; System.out.print("Would you like milk and sugar with your coffee (y/n)? "); BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); try { answer = in.readLine(); } catch (IOException ioe) { System.err.println("IO error trying to read your answer"); } if (answer == null) { return "no"; } return answer; } }
TeaWithHook.java
import java.io.*; public class TeaWithHook extends CaffeineBeverageWithHook { public void brew() { System.out.println("Steeping the tea"); } public void addCondiments() { System.out.println("Adding Lemon"); } public boolean customerWantsCondiments() { String answer = getUserInput(); if (answer.toLowerCase().startsWith("y")) { return true; } else { return false; } } private String getUserInput() { // get the user's response String answer = null; System.out.print("Would you like lemon with your tea (y/n)? "); BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); try { answer = in.readLine(); } catch (IOException ioe) { System.err.println("IO error trying to read your answer"); } if (answer == null) { return "no"; } return answer; } }
BeverageTestDrive.java
public class BeverageTestDrive { public static void main(String[] args) { TeaWithHook teaHook = new TeaWithHook(); CoffeeWithHook coffeeHook = new CoffeeWithHook(); System.out.println("\nMaking tea..."); teaHook.prepareRecipe(); System.out.println("\nMaking coffee..."); coffeeHook.prepareRecipe(); } }
二、结果
三、解释
1、模板方法模式:在一个方法中定义一个算法的框架,而将步骤子类中。模板方法使得子类在不改变算法结构的情况下,重新定义算法中的某一步骤。
2、OO原则:别找我,我会找你。由超类主控一切,当他们需要的时候,自动去调用子类。这就和好莱坞一样。
四、Array.Sort(x implements Comparable);也是模板方法模式。