设计模式（责任链模式）

public abstract class Handler {
    public Handler next;
    
    public Handler setNext(Handler handler){
        this.next = handler;
        return this;
    }
    
    public abstract void doAction();
}

public class HandlerOneImpl extends Handler {

    @Override
    public void doAction() {
        if(null != this.next){
            this.next.doAction();
        }
        
        System.out.println("HandlerOneImpl");
    }
}

public class HandlerTwoImpl extends Handler {

    @Override
    public void doAction() {
        if(null != this.next){
            this.next.doAction();
        }
        
        System.out.println("HandlerTwoImpl");
    }
}

public class App {

    public static void main(String[] args) {
        HandlerOneImpl one = new HandlerOneImpl();
        one.setNext(new HandlerTwoImpl()).doAction();
    }
}

HandlerTwoImpl
HandlerOneImpl