Java装饰器设计模式初探

本篇随笔主要介绍用Java实现简单的装饰器设计模式：

先来看一下装饰器设计模式的类图：

从图中可以看到，我们可以装饰Component接口的任何实现类，而这些实现类也包括了装饰器本身，装饰器本身也可以再被装饰。

下面是用Java实现的简单的装饰器设计模式，提供的是从基本的加入咖啡入手，可以继续加入牛奶，巧克力，糖的装饰器系统。

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();  }}

运行结果：

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