装饰器模式

装饰器模式允许向一个现有的对象添加新的功能，同时又不改变原始结构。装饰类是现有类的一个包装。

基础接口：

1 public interface Component {
2 
3     void operation();
4 }

原始类：

1 public class ConcreComponent implements Component {
2 
3     @Override
4     public void operation() {
5         System.out.println("concre component");
6     }
7 }

抽象装饰器：

 1 public abstract class BaseDecorator implements Component {
 2 
 3     public Component component;
 4 
 5     public BaseDecorator(Component component) {
 6         this.component = component;
 7     }
 8 
 9     @Override
10     public void operation() {
11         this.component.operation();
12     }
13 }

自定义装饰器：

 1 public class ConcreDecorator extends BaseDecorator {
 2 
 3     public ConcreDecorator(Component component) {
 4         super(component);
 5     }
 6 
 7     @Override
 8     public void operation() {
 9         this.component.operation();
10         decorateMethod();
11     }
12 
13     public void decorateMethod() {
14         System.out.println("decorateMethod");
15     }
16 }

测试方法：

public class Main {

    public static void main(String[] args) {
        Component concreComponent = new ConcreComponent();
        ConcreDecorator concreDecorator = new ConcreDecorator(concreComponent);
        concreDecorator.operation();
    }
}