装饰者模式

简介

结构型模式，通过对真实对象的一层又一层包装，可以给对象添加很多额外的功能，调用起来感觉很复杂。

示例

public interface Componet {
    void doSomeThing();
}

public class ConcreteComponet implements Componet{
    @Override
    public void doSomeThing() {
        System.out.println("do some thing");
    }
}

public class SayHiDecorator implements Componet{
    private Componet componet;

    public SayHiDecorator(Componet componet){
        this.componet = componet;
    }
    @Override
    public void doSomeThing() {
        System.out.println("Hi!");
        componet.doSomeThing();
    }
}

public class SayThanksDecorator implements Componet{
    private Componet componet;

    public SayThanksDecorator(Componet componet){
        this.componet = componet;
    }
    @Override
    public void doSomeThing() {
        componet.doSomeThing();
        System.out.println("Thanks!");
    }
}

调用

@Test
public void tt(){
    Componet componet = new SayThanksDecorator(new SayHiDecorator(new ConcreteComponet()));
    componet.doSomeThing();
}

控制台打印：

Hi!

do some thing

Thanks!