Java裝飾器設計模式初探

2019-11-26 13:49:06

字體：大中小

來源：轉載

供稿：網友

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：