paul198247 (S.Battier) 于 (Mon Jul 12 00:30:59 2010, 美东) 提到:
如果让设计一个多部电梯的控制系统，画出uml图。请问大概要设计哪些类，类之间的 关系？ 我是最近才看OOD的，比较菜 我是这么想的： 主系统 System包含了taskcenter，elevator 任务系统taskcenter负责给不同电梯增加任务，删除任务，响应不同电梯内的任务请求 ，每层用户的请求
电梯elevator 包括了自己的任务list，方向，以及状态。电梯类有2个子类，一个是UI elevator，一个是task_elevator。UI_elevator函数有addrequest， removerequest，askforhelp，opendoor，closedoor这些是给电梯内的用户的；task elevator有getdirection，getcondition，getrequest，addtask， removetask等函数 ，这些是给taskcenter调用。
request 有2种子类，一种是elevatorrequest，是UI_elevator发出的；一种是 floorrequest，是每层电梯外用户发出的。
taskcenter和request，UI_elevator和request的关系应该是关联关系 taskcenter和task_elevator的关系应该是聚合吧。
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boyjemmy (jemmyboy) 于 (Mon Jul 12 18:52:30 2010, 美东) 提到:
先说说我对单个电梯设计的想法（欢迎批评指正）
1 Elevator Object, 应该包含physical components: Door, Indicator Lights, Control Panel. 一些性质(Non physical properties): Speed, Num of floors, capacity, max weight. 所能从事的操作methods: moveto, stop, ringbell。然后电 梯应该能够handle user request, 所以还应有一个requestQueue, 电梯应该根据自己 的state 和 requestQueue做出moveto, stop的决定，所以有一component: requestHandler(Strategy pattern),可以set不同的requestHanlder.
2 Door, properties: State, method: open, close， getState.
3 Indicator light(指示所到楼层），properties: state; method: on, off, getState
4 Control Panel, 包含physical component: Floor Buttons, Other buttons(也可直 接把Buttons 当作 elevator的components，还没考虑哪一个方法好）
5 Button, properties: floorNum, Parent Elevator, methods: OnPress(Observer Pattern).
6 ElevatorRequestHandler: handleRequest(Elevator ele, requestList rlist), 可 以define 一个interface, 然后又各种不同实现
7 Request: 可以define 一个abstract class, 然后有子类movingRequest, helpRequest doorRequest etc.
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paul198247 (S.Battier) 于 (Wed Jul 14 00:32:35 2010, 美东) 提到:
考虑的很全面啊,多谢
面试中让用OOD方法设计一个系统，比如说电梯。是不是应该请把系统需求说清楚，比 如说电梯响应请求的策略，是先来先服务，还是就近服务。我觉得用户应该提供策略， programmer根据用户的要求设计软件系统。
而面试的时候，interviewer往往说的很笼统，就说让你设计一个电梯系统，而设计一 个实际系统是要考虑很多问题，不仅仅是软件设计的问题，interviewer是不是应该提 供准确的需求呢。
另一个例子，设计一个PARKING LOT。我们平常的PARKINGLOT都是自己进去停车，然后 出门时候付钱，比较简单，我一开始按这个思路设计，但跟interviewer说的时候，他 问我怎么分配parking spaces，他认为系统应该自动分配，而不是司机自己进去找。这 样我就要从新设计，耽误了时间，打乱了思路。是不是应该一开始就和INTERVIEWER敲 定系统是怎么工作的，然后在OOD设计。
大家都是怎么做的？
感觉面试官也没有固定答案但还算满意我的回答 前面有人说是client/server，那你得设计server side怎么做
当时我给了一个object model并大概pseudo code实现了关键的几个class 还有需求也是我当时定义的，就是说 你设计的电梯应该是什么样子有什么功能等 感觉当时面试官对这个也比较重视
这题太open，不同的面试官期待的东西不一样 最好能试探或感应一下面试官想要什么
贴个我以前写的，仅供参考，肯定不是标准解 包括控制系统和电梯厢两个类
class ElevatorSystem { public: struct SystemSetup{ int totalFloors; int totalElevators; };
ElevatorSystem(SystemSetup &);
~ElevatorSystem(void);
void requestUp(int floor);
void requestDown(int floor);
private: int totalFloors; int totalElevators; Elevator *elevators; enum RequestType {NONE, UP, DOWN}; RequestType requests; void resetRequest(int floor); };
class Elevator { public: Elevator(int id, int totalFloors); ~Elevator(void);
enum ElevatorStatus {RUNNING, IDLE, STOPPED};
enum RunningStatus {UP, DOWN, STAND};
ElevatorStatus elevatorStatus;
RunningStatus runningStatus;
void stop();
int currentFloor;
int *stopRequestList; // one stop request slot on each floor
queue<int> destinationList;
private: int id; int totalFloors; int currentPassengers; };
把照片用ocr拷了前面几段话
Design an elevator system at a shopping complex using java threads to support multithreading.
Solution: Let us understand the scenarios which need to be considered while designing an elevator system. Shoppers arrive in the building at random times. During the time a shopper is in the building he may request elevator service from the floor where he is currently located. The request always specifies a direction, up or down. Shoppers on the lowest floor may only request up service; those on the top floor may only request down service; all others may request either service.
On entering an elevator a shopper selects a destination floor. The elevator then closes its doors and moves to that destination floor, possibly stopping on intermediate floors to deliver other shoppers who may have selected intermediate floors. When an elevator arrives at a destination floor it stops, opens its doors, and discharges any shoppers who have selected that floor. Having stopped, opened its doors and unloaded its passengers, the elevator then admits any shoppers who may be waiting for service in the direction the elevator may be currently moving, subject to the restriction that the elevator may not exceed its capacity to carry passengers. Shoppers who do not succeed in boarding the elevator because it is full must make a fresh request to obtain service at the floor on which they are waiting.
For our implementation, we can assume that the elevator moves passengers from floor to floor in simulation. The basic objects of the system are: Elevator, Person, Building and the Simulator which controls the elevators. Elevator class keeps track of current state of it (whether it is moving up or down), its capacity, set-vice time required at each floor and time required to move to next floor, current number of passengers on elevator, number of passengers getting off at each floor while moving etc... Operations on Elevator object are synchronized to make the system thread safe.
21这种问题都起始于OO Design，那些Object，怎么关系啥的。帮人帮到底，送佛送到西， 讲讲通常情况下，这种design问题的答题方法（对于多数面试官适用，当然也有例外） 。 这种问题首先明确要干啥，也就是需求分析，不要上来就开搞。比如parking lot，设计 是parking lot的管理？还是charge system？还是啥其他相关问题。这个很重要，决定 了你的设计。 其次，要求几个具体user case。比如，parking lot，可能要求用户能walk-in and pa rk；要求用户能提前预订；能cancel reservation。user caess也决定了你的design， 也体现了你良好的沟通能力。 然后就是Logical Model或者physical model的design。需要啥Objects（比如 Garage, Lot, Customer, Car）。 然后他们的关系，比如Garage to Lot (1 - m)。在兽一下OO的继承关系(比如car有tru ck, sedan, SUV啥的；Lot有大lot，小lot，残帕啥的) 然后根据
http://www.weiming.info/zhuti/JobHunting/31956527/
http://yang-algorithm.blogspot.com/2010/01/amazon-interview-question-design-oo.html