责任链

每个审批者作为链中的处理节点只处理一件事情，比如servlet过滤器

import java.util.ArrayList;
import java.util.List;

interface Handler {
    //实现类自己实现，放行返回true，中止返回false
    boolean handle(Object param);
}

class HandlerChain {
    private final List<Handler> handlers;

    private HandlerChain(List<Handler> handlers) {
        this.handlers = handlers;
    }

    public static class Builder {
        private final List<Handler> handlers = new ArrayList<>();

        public HandlerChain.Builder next(Handler handler) {
            handlers.add(handler);
            return this;
        }

        public HandlerChain build() {
            return new HandlerChain(handlers);
        }
    }

    public void doChain(Object param) {
        for (Handler handler : handlers) {
            if (!handler.handle(param)) {
                break;
            }
        }
    }

    public void reverseDoChain(Object param) {
        for (int i = handlers.size() - 1; i >= 0; i--) {
            if (!handlers.get(i).handle(param)) {
                break;
            }
        }
    }
}

class Main {
    public static void main(String[] args) {
        HandlerChain handlerChain = new HandlerChain.Builder()
                .next(param -> {
                    System.out.println("A");
                    return true;
                })
                .next(param -> {
                    System.out.println("B");
                    return false;
                })
                .next(param -> {
                    System.out.println("C");
                    return true;
                })
                .build();
        handlerChain.doChain(null);
        System.out.println();
        handlerChain.reverseDoChain(null);
    }
}