设计模式——责任链模式

public abstract class Handler<T> {

    protected Handler<T> next;

    private void next(Handler<T> next) {
        this.next = next;
    }

    public abstract void doHandler(T data);

    public static class Builder<T> {
        private Handler<T> head;
        private Handler<T> tail;

        public Builder<T> addHandler(Handler<T> handler) {
            if (this.head == null) {
                this.head = this.tail = handler;
                return this;
            }
            this.tail.next(handler);
            this.tail = handler;
            return this;
        }

        public Handler<T> build() {
            return this.head;
        }
    }
}

public class AHandler extends Handler {
    @Override
    public void doHandler(Object data) {
        System.out.println("A:" + data.toString());
        if (Objects.nonNull(next)) {
            next.doHandler(data);
        }
    }
}

public class BHandler extends Handler{
    @Override
    public void doHandler(Object data) {
        System.out.println("B:" + data.toString());
    }
}

public class Test {

    public static void main(String[] args) {
        Handler.Builder builder = new Handler.Builder<>()
                .addHandler(new AHandler())
                .addHandler(new BHandler());
        builder.build().doHandler("当我遇上你");
    }
}