设计模式-装饰者模式

结构图：

实现：

1 abstract public class Component {
2     abstract public void operation();
3 }

public class ConcreteComponent extends Component {

    @Override
    public void operation() {
        System.out.println("具体操作");
    }

}

 1 public class Decorator extends Component{
 2     protected Component component;
 3     
 4     public void setComponent(Component c)
 5     {
 6         component = c;
 7     }
 8 
 9     @Override
10     public void operation() {
11         if (component != null)
12             component.operation();
13     }
14 
15 }

 1 public class ConcreteDecoratorA extends Decorator{
 2 
 3     @Override
 4     public void operation() {
 5         super.operation();
 6         
 7         System.out.println("增加装饰A的操作");
 8     }
 9     
10 
11 }

 1 public class ConcreteDecoratorB extends Decorator{
 2 
 3     @Override
 4     public void operation() {
 5         super.operation();
 6         
 7         System.out.println("增加装饰B的操作");
 8     }
 9     
10 
11 }

 1 public class Client {
 2     public static void main(String[] args)
 3     {
 4         ConcreteComponent cc = new ConcreteComponent();
 5         ConcreteDecoratorA cda = new ConcreteDecoratorA();
 6         ConcreteDecoratorB cdb = new ConcreteDecoratorB();
 7         
 8         cda.setComponent(cc);
 9         cdb.setComponent(cda);
10         cdb.operation();
11         
12     }
13 }

应用场景：

适应于给一个对象动态添加额外的功能。