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     @Override10     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。