Java设计模式（七） 模板模式-使用钩子

1，模板类

package com.pattern.template;

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;
	}

}

2，模板的子类实现类

package com.pattern.template;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class CoffeeWithHook extends CaffeineBeverageWithHook{

	/** 
	 * @see com.pattern.template.CaffeineBeverageWithHook#brew()
	 */
	@Override
	void brew() {
		System.out.println("Dripping Coffee through filter");
	}

	/** 
	 * @see com.pattern.template.CaffeineBeverageWithHook#addCondiments()
	 */
	@Override
	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.println("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 e) {
			System.out.println("IO Exception!");
		}
		
		if(answer == null){
			return "no";
		}
		return answer;
	}

}

3，测试类

package com.pattern.template;

public class BeverageTestDrive {
	
	public static void main(String[] args) {

		CoffeeWithHook coffeeHook = new CoffeeWithHook();
		System.out.println("
Making tea...");
		coffeeHook.prepareRecipe();
	}
}

4，输出结果：

Making tea...
Boiling water
Dripping Coffee through filter
Pouring into cup
Would you like milk and sugar with your coffee (y/n)?
y
Adding Sugar and Milk