装饰器模式

1. 装饰器模式结构图

   

2. 示例代码：

   // 抽象公共类
   public abstract class Component {
   
       public abstract void work();
   }
   
   // 具体被装饰对象
   public class People extends Component{
       @Override
       public void work() {
           System.out.println("开始起床去上班．．．．．．");
       }
   }
   
   // 抽象装饰器类
   public abstract class WearDecorator extends Component{
   
       protected Component component;
   
       public WearDecorator(Component component) {
           this.component = component;
       }
   }
   
   //　具体装饰类１
   public class ShoeDecorator extends WearDecorator{
       public ShoeDecorator(Component component) {
           super(component);
       }
   
       @Override
       public void work() {
           component.work();
           System.out.println("穿上运动鞋．．．．．．");
       }
   }
   
   //　具体装饰类２
   public class ShirtDecorator extends WearDecorator{
       public ShirtDecorator(Component component) {
           super(component);
       }
   
       @Override
       public void work() {
           component.work();
           System.out.println("穿上Ｔ恤．．．．．．");
       }
   }
   
   
   //　具体装饰类３
   public class PantsDecorator extends WearDecorator{
       public PantsDecorator(Component component) {
           super(component);
       }
   
       @Override
       public void work() {
           component.work();
           System.out.println("穿上运动裤．．．．．．");
       }
   }
   
   //　具体装饰类４
   public class HatDecorator extends WearDecorator{
       public HatDecorator(Component component) {
           super(component);
       }
   
       @Override
       public void work() {
           component.work();
           System.out.println("戴上网球帽．．．．");
       }
   }
   
   //　测试
   public class DecoratorTest {
   
       public static void main(String[] args) {
           People people = new People();
           ShirtDecorator shirt = new ShirtDecorator(people);
           PantsDecorator pants = new PantsDecorator(shirt);
           ShoeDecorator shoes = new ShoeDecorator(pants);
           HatDecorator hat = new HatDecorator(shoes);
           hat.work();
       }
   }
   
   

3. 总结：

   优点：可以动态的给一个对象扩展功能，即插即用，可以通过不同的装饰器排列组合，实现不同效果，并且遵循开闭原则；

   缺点：会出现更多代码和类，增加了程序的复杂性．