注：示例來自《大話設計模式》

現有如下要求 寫一個可以給人搭配不同的服飾的系統 程式碼如下

Person類

package Test06;

public class Person {

    private String name;
    public Person(String name)
    {
        this.name = name;
    }

    public void WearTShirts()
    {
        System.out.print("大T恤 ");
    }

    public void WearBigTrouser
 
()
    {
        System.out.print("垮褲 ");
    }

    public void WearSneakers()
    {
        System.out.print("破球鞋 ");
    }

    public void WearSuit()
    {
        System.out.print("西裝 ");
    }

    public void WearTie()
    {
        System.out.print("領帶 ");
    }

    public void WearLeatherShoes
 
()
    {
        System.out.print("皮鞋 ");
    }

    public void Show()
    {
        System.out.print("裝扮的"+name);
    }

}

客戶端程式碼

package Test06;

public class Program {

    public static void main(String[] args)
    {
        Person xc = new Person("小菜");

        System.out.println("\n第一種裝扮："
 
);

        xc.WearTShirts();
        xc.WearBigTrouser();
        xc.WearSneakers();
        xc.Show();

        System.out.println("\n第二種裝扮：");

        xc.WearSuit();
        xc.WearTie();
        xc.WearLeatherShoes();
        xc.Show();

    }

}

現在有個問題就是如果需要增加超人的裝扮 該如何做呢
需要改Person類 違背了開放-封閉原則 應該把服飾都寫成子類
重構後代碼如下

Person類

package Test06;

public class Person {

    private String name;
    public Person(String name)
    {
        this.name = name;
    }

    public void Show()
    {
        System.out.print("裝扮的"+name);
    }

}

服飾抽象類

package Test06;

public abstract class Finery {

    public abstract void Show();

}

各種服飾子類

package Test06;

public class TShirts extends Finery {

    @Override
    public void Show() {
        System.out.print("大T恤 ");   
    }   

}

package Test06;

public class BigTrouser extends Finery {

    @Override
    public void Show() {
        System.out.print("垮褲 ");    
    }

}

package Test06;

public class Sneakers extends Finery {

    @Override
    public void Show() {
        System.out.print("破球鞋 ");
    }

}

package Test06;

public class Suit extends Finery {

    @Override
    public void Show() {
        System.out.print("西裝 ");
    }
}

package Test06;

public class Tie extends Finery {

    @Override
    public void Show() {
        System.out.print("領帶 ");
    }
}

package Test06;

public class LeatherShoes extends Finery {

    @Override
    public void Show() {
        System.out.print("皮鞋 ");
    }
}

客戶端程式碼

package Test06;

public class Program {

    public static void main(String[] args)
    {
        Person xc = new Person("小菜");

        System.out.println("\n第一種裝扮：");

        Finery dtx = new TShirts();
        Finery kk = new BigTrouser();
        Finery pqx = new Sneakers();

        dtx.Show();
        kk.Show();
        pqx.Show();
        xc.Show();

        System.out.println("\n第二種裝扮：");

        Finery xz = new Suit();
        Finery ld = new Tie();
        Finery px = new LeatherShoes();

        xz.Show();
        ld.Show();
        px.Show();
        xc.Show();

    }

}

上面的程式碼是一個詞一個詞顯示出來的 就好比 光著身子 當著大家的面 先穿 T恤 再穿褲子 再穿鞋 應該把所需的功能按正確的順序串聯起來進行控制 用裝飾模式看看如何實現 程式碼如下

Person類

package Test06;

public class Person {

    public Person()
    { }

    private String name;
    public Person(String name)
    {
        this.name = name;
    }

    public void Show()
    {
        System.out.print("裝扮的"+name);
    }

}

服飾類

package Test06;

public class Finery extends Person {

    protected Person component;

    //打扮
    public void Decorate(Person component)
    {
        this.component = component;
    }
    @Override
    public void Show()
    {
        if (component != null)
        {
            component.Show();
        }
    }
}

具體服飾類

package Test06;

public class TShirts extends Finery {

    @Override
    public void Show() {
        System.out.print("大T恤 ");
        super.Show();
    }   

}

package Test06;

public class BigTrouser extends Finery {

    @Override
    public void Show() {
        System.out.print("垮褲 ");
        super.Show();
    }

}

package Test06;

public class Sneakers extends Finery {

    @Override
    public void Show() {
        System.out.print("破球鞋 ");
        super.Show();
    }

}

package Test06;

public class Suit extends Finery {

    @Override
    public void Show() {
        System.out.print("西裝 ");
        super.Show();
    }
}

package Test06;

public class Tie extends Finery {

    @Override
    public void Show() {
        System.out.print("領帶 ");
        super.Show();
    }
}

package Test06;

public class LeatherShoes extends Finery {

    @Override
    public void Show() {
        System.out.print("皮鞋 ");
        super.Show();
    }
}

客戶端程式碼

package Test06;

public class Program {

    public static void main(String[] args)
    {
        Person xc = new Person("小菜");

        System.out.println("\n第一種裝扮：");

        Sneakers pqx = new Sneakers();
        BigTrouser kk = new BigTrouser();
        TShirts dtx = new TShirts();

        pqx.Decorate(xc);
        kk.Decorate(pqx);
        dtx.Decorate(kk);
        dtx.Show();

        System.out.println("\n第二種裝扮：");

        LeatherShoes px = new LeatherShoes();
        Tie ld = new Tie();
        Suit xz = new Suit();

        px.Decorate(xc);
        ld.Decorate(px);
        xz.Decorate(ld);
        xz.Show();

    }

}

裝飾模式是為已有功能動態地新增更多功能的一種方式 它把每個要裝飾的功能放在單獨的類中 並讓這個類包裝它所要裝飾的物件 可以在執行時 根據需要有選擇地 按順序地使用裝飾功能包裝物件

缺點：會產生過多的相似的物件 不容易排錯