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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