装饰者模式

代码详解：【设计模式】Java 设计模式之装饰者模式（Decorator）_java 装饰者模式-CSDN博客

// 抽象构件角色
public interface Component {
    void operation();
}

// 具体构件角色
public class ConcreteComponent implements Component {
    @Override
    public void operation() {
        System.out.println("执行具体构件对象的操作");
    }
}

// 装饰角色
public class Decorator implements Component {
    protected Component component;

    public Decorator(Component component) {
        this.component = component;
    }

    @Override
    public void operation() {
        if (component != null) {
            component.operation();
        }
    }
}

// 具体装饰角色A
public class ConcreteDecoratorA extends Decorator {
    public ConcreteDecoratorA(Component component) {
        super(component);
    }

    @Override
    public void operation() {
        super.operation();
        addedFunctionA();
    }

    public void addedFunctionA() {
        System.out.println("为构件对象添加功能A");
    }
}

// 具体装饰角色B
public class ConcreteDecoratorB extends Decorator {
    public ConcreteDecoratorB(Component component) {
        super(component);
    }

    @Override
    public void operation() {
        super.operation();
        addedFunctionB();
    }

    public void addedFunctionB() {
        System.out.println("为构件对象添加功能B");
    }
}

装者模式的应用：

-mybatis 里的缓存：