装饰者模式-星巴克

例子一、咖啡的制作

/**
 * 饮料类
 */
public abstract class Beverage {
	//描述
	String description = "Unknown Beverage";
	
	public String getDescription(){
		return description;
	}
	
	//价格
	public abstract double cost();
}

/**
 * 调料类
 */
public abstract class CondimentDecorator extends Beverage{
	
	//所有的调料装饰者都必须重新实现该方法
	public abstract String getDescription();
}

/**
 * 浓咖啡,是一种饮料
 */
public class Espresso extends Beverage{

	public Espresso(){
		description = "Espresso";
	}
	
	@Override
	public double cost() {
		
		return 1.99;
	}
	
}

/**
 * 混合咖啡
 */
public class HouseBlend extends Beverage{

	public HouseBlend(){
		description = "House Blend Coffee";
	}
	
	@Override
	public double cost() {
		
		return 0.89;
	}

}

/**
 * 摩卡,一种调料
 */
public class Mocha extends CondimentDecorator{

	Beverage beverage;
	
	public Mocha(Beverage beverage){
		this.beverage = beverage;
	}
	
	@Override
	public String getDescription() {
		
		return beverage.getDescription() + ",Mocha";
	}

	@Override
	public double cost() {
		
		return 0.20 + beverage.cost();
	}

}

/**
 * 星巴克咖啡的制作
 */
public class StarbuzzCoffee {
	
	public static void main(String[] args) {
		Beverage beverage1 = new Espresso();//浓咖啡,不需要调料
		System.out.println(beverage1.getDescription() + " $" + beverage1.cost());
		
		Beverage beverage2 = new HouseBlend();//混合咖啡,需要调料
		beverage2 = new Mocha(beverage2);
		System.out.println(beverage2.getDescription() + " $" + beverage2.cost());
		
	}
	/**
	 * 运行结果:
	 * Espresso $1.99
	   House Blend Coffee,Mocha $1.09
	 */
}

例子二、io流的装饰

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * 编写自己的java IO装饰者
 * 把流内的所有大写字符转成小写
 * FilterInputStream 包含其他一些输入流，它将这些流用作其基本数据源，
 * 它可以直接传输数据或提供一些额外的功能。FilterInputStream 类本身只
 * 是简单地重写那些将所有请求传递给所包含输入流的 InputStream 的所有方法。
 */
public class LowerCaseInputStream extends FilterInputStream{

	/**
	 * @param in
	 */
	protected LowerCaseInputStream(InputStream in) {
		super(in);
	}

	//重写,转化为小写
	@Override
	public int read() throws IOException {
		int c = super.read();
		return (c == -1 ? c : Character.toLowerCase((char)c));
	}

	//重写,转化为小写
	@Override
	public int read(byte[] b, int off, int len) throws IOException {
		int result = super.read(b, off, len);
		for(int i = off; i < off + result; i++){
			b[i] = (byte)Character.toLowerCase((char)b[i]);
		}
		return result;
	}
	
}

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * 测试java IO装饰者
 */
public class TestLowerCaseInStr {
	public static void main(String[] args) throws IOException {
		int c;
		InputStream in = new LowerCaseInputStream(new BufferedInputStream(new FileInputStream("C:\\Format.txt")));
		while((c = in.read()) >= 0){
			System.out.println((char)c);
		}
		in.close();
	}
}