装饰者模式-星巴克

青旅半醒 2022-09-08 04:59 184阅读 0赞

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();
    	}
    }