设计模式--装饰者模式

咖啡馆订单项目：

　　1）、咖啡种类：Espresso、ShortBlack、LongBlack、Decaf

　　2）、调料：Milk、Soy、Chocolate

　　3）、扩展性好、改动方便、维护方便

一个差的方案:

一个好一点的设计方案

有些问题 : 　　1）增删调料种类　　 2）添加多份问题

装饰者模式就像打包一个快递

　　1）主体：陶瓷、衣服

　　2）包装：报纸填充、塑料泡沫、纸板、木板

装饰者模式：

装饰者模式： 动态的将新功能附加到对象上。在对象功能扩展方面，它比继承更有弹性。

用装饰者模式重新设计的方案

装饰者模式下的订单：2份巧克力+一份牛奶的LongBlack

对应代码演示：

package com.java.jikexueyuan.coffeebar;

public abstract class Drink {
public String description="";
private float price=0f;;

public void setDescription(String description)
{
this.description=description;
}

public String getDescription()
{
return description+"-"+this.getPrice();
}
public float getPrice()
{
return price;
}
public void setPrice(float price)
{
this.price=price;
}
public abstract float cost();

}

package com.java.jikexueyuan.coffeebar.coffee;

import com.java.jikexueyuan.coffeebar.Drink;

public  class Coffee extends Drink {//单品

@Override
public float cost() {
// TODO Auto-generated method stub
return super.getPrice();
}

}

package com.java.jikexueyuan.coffeebar.coffee;

public class LongBlack extends Coffee{//单品

public LongBlack()
{
super.setDescription("LongBlack");
super.setPrice(6.0f);
}

}

package com.java.jikexueyuan.coffeebar.decorator;

import com.java.jikexueyuan.coffeebar.Drink;

public  class Decorator extends Drink {
private Drink Obj;

public Decorator(Drink Obj){
this.Obj=Obj;
};

@Override
public float cost() {
// TODO Auto-generated method stub
return super.getPrice()+Obj.cost();
}

@Override
public String getDescription()
{
return super.description+"-"+super.getPrice()+"&&"+Obj.getDescription();
}

}

package com.java.jikexueyuan.coffeebar.decorator;

import com.java.jikexueyuan.coffeebar.Drink;

public class Milk extends Decorator {//调料

public Milk(Drink Obj) {
super(Obj);
// TODO Auto-generated constructor stub
super.setDescription("Milk");
super.setPrice(2.0f);
}

}

package com.java.jikexueyuan.coffeebar.decorator;

import com.java.jikexueyuan.coffeebar.Drink;

public class Chocolate extends Decorator {//调料

public Chocolate(Drink Obj) {
super(Obj);
// TODO Auto-generated constructor stub
super.setDescription("Chocolate");
super.setPrice(3.0f);
}

}

测试方法：

public static void main(String[] args) {

Drink order;
order=new Decaf();
System.out.println("order1 price:"+order.cost());
System.out.println("order1 desc:"+order.getDescription());

System.out.println("********包装开始********");
order=new LongBlack();
order=new Milk(order);
order=new Chocolate(order);
order=new Chocolate(order);
System.out.println("order2 price:"+order.cost());
System.out.println("order2 desc:"+order.getDescription());

}

Java里装饰者介绍

扩展自定义IO

package com.java.jikexueyuan.myiodecorator;

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

public class UpperCaseInputStream extends FilterInputStream{

protected UpperCaseInputStream(InputStream in) {
super(in);
// TODO Auto-generated constructor stub
}

public int read() throws IOException
{
int c=super.read();
return c==-1?c:Character.toUpperCase((char)(c));
}
public int read(byte[] b,int offset,int len) throws IOException
{
int result=super.read(b,offset,len);
for(int i=0;i<result;i++)
{
b[i]=(byte)Character.toUpperCase((char)(b[i]));
}

return result;
}
}

package com.java.jikexueyuan.myiodecorator;

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

public class InputTest {
public static void main(String[] args) {
int c;
try {
InputStream in = new UpperCaseInputStream(new BufferedInputStream(
new FileInputStream("F:\\test.txt")));
while((c=in.read())>=0)
{
System.out.print((char)c);

}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
}