设计模式-装饰者模式

• 定义
• 结构图
• 使用场景
• 代码实现
• • Java代码实现
  • python代码实现

装饰者模式动态地将责任附加到对象上。若要扩展功能，装饰者提供了比继承更有弹性的替代方案。

可用于功能的扩展，也就是为对象新增额外的行为。

先建立一个抽象类，所有类都继承这个抽象类

public abstract class component{
	String description = "None";

	public String getDescription(){
		return description;
	} 
}

在创建一个被继承者

public class People extends Component{
	String description = "I am people.I can working";

	public String getDescription(){
		return description;
	}
}

接着创建一个装饰者

public class Shopping extends Component{
	String description = "shopping";
	private Component component;

	public Shopping(Component component){
		this.component = component;
	}
	
	@Override
	public String getDescription(){
		return component.getDescription + "," + description + ".";
	}
}

最后运行文件

public class Run{
	public static void main(String[] args){
		Component people = new People();
		System.out.println(people.getDescription());

		Component Shopping = new Shopping(people):
		System.out.println(Shopping.getDescription());
	}
}

运行结果：>>I am people.I can working. >> I am people.I can working,shopping.

被装饰者

class People:
    def __init__(self):
        self.description = "I am people.I can working"
    def getDescription(self):
        return self.description + "."

装饰者

class Shopping:
    def __init__(self,people):
        self.description = ",shoping"
        self.people = people
    def getDescription(self):
        return self.people.getDescription() + self.description + "."

运行文件

people = People()
print(people.getDescription())
shopping = Shopping(people)
print(shopping.getDescription())

运行结果：>>I am people.I can working. >>I am people.I can working.,shoping.