該模式又稱為包裝模式，允許向一個現(xiàn)有的對象添加新的功能，同時又不改變其結(jié)構(gòu)，就像一種裝飾一樣，動態(tài)的將功能附加到別的類中。其實這種模式比較常見，例如Java中的io類就是利用了這種模式。一個簡單的輸入輸出流經(jīng)過包裝可以有各種功能。簡單實現(xiàn)：

抽象類

public interface Beverage {
    void make();
}

基本實現(xiàn)類(被裝飾對象)

public class Coffee implements Beverage{
    @Override
    public void make() {
        System.out.println("make coffee");
    }
}

裝飾者

public abstract class AdditivesBeverage implements Beverage{
    private Beverage beverage;

    public AdditivesBeverage(Beverage beverage){
        this.beverage = beverage;
    }

    @Override
    public void make() {
        beverage.make();
    }
}

裝飾者具體實現(xiàn)

public class AdvancedCoffee extends AdditivesBeverage {
    public AdvancedCoffee(Beverage beverage) {
        super(beverage);
    }

    private void addSugar(){
        System.out.println("add sugar");
    }

    private void addMilk(){
        System.out.println("add milk");
    }

    @Override
    public void make() {
        super.make();
        addSugar();
        addMilk();
    }
}

測試類

public class test {
    public static void main(String[] args) {
        AdditivesBeverage beverage = new AdvancedCoffee(new Coffee());
        beverage.make();
    }
}