Java裝飾器設計模式初探

本篇隨筆主要介紹用Java實現簡單的裝飾器設計模式：

先來看一下裝飾器設計模式的類圖：

從圖中可以看到，我們可以裝飾Component接口的任何實現類，而這些實現類也包括了裝飾器本身，裝飾器本身也可以再被裝飾。

下面是用Java實現的簡單的裝飾器設計模式，提供的是從基本的加入咖啡入手，可以繼續加入牛奶，巧克力，糖的裝飾器系統。

 interface Component { void method();}class Coffee implements Component { @Override public void method() { // TODO Auto-generated method stub System.out.println("倒入咖啡"); } }class Decorator implements Component { public Component comp; public Decorator(Component comp) { this.comp = comp; } @Override public void method() { // TODO Auto-generated method stub comp.method(); } }class ConcreteDecorateA extends Decorator { public Component comp; public ConcreteDecorateA(Component comp) { super(comp); this.comp = comp; } public void method1() { System.out.println("倒入牛奶"); } public void method2() { System.out.println("加入糖"); } public void method() { super.method(); method1(); method2(); }}class ConcreteDecorateB extends Decorator { public Component comp; public ConcreteDecorateB(Component comp) { super(comp); this.comp = comp; } public void method1() { System.out.println("加入巧克力"); } public void method() { super.method(); method1(); }}public class TestDecoratePattern { public static void main(String[] args) { Component comp = new Coffee(); comp.method(); System.out.println("--------------------------------------------------"); Component comp1 = new ConcreteDecorateA(comp); comp1.method(); System.out.println("--------------------------------------------------"); Component comp2 = new ConcreteDecorateB(comp1); comp2.method(); System.out.println("--------------------------------------------------"); Component comp3 = new ConcreteDecorateB(new ConcreteDecorateA(new Coffee())); comp3.method(); System.out.println("--------------------------------------------------"); Component comp4 = new ConcreteDecorateA(new ConcreteDecorateB(new Coffee())); comp4.method(); }}

運行結果：

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