我有一个简化的设计,如下所示(基本上是一堆处理程序来处理两种不同类型的请求:EventRequest和SpeechRequest)。以下是伪代码:
class SpeechRequest {sessionId: String; slot: String}
class EventRequest {sessionId: String; event: String}
class SpeechRequestHandler;
class EventRequestHandler;
class SpeechRequestHandler[A/B/C] extends SpeechRequestHandler {
- handle(request: SpeechRequest) {
doSt(request.slot)
}
}
class EventRequestHandler[A/B/C] extends EventRequestHandler {
- handle(request: EventRequest) {
doSt(request.event)
}
}
有两种不同的调度程序用于查找适当的处理程序以处理每种类型的请求并将它们转发到处理程序进行处理:
class SpeechDispatcher {
- handle(request: SpeechRequest) {
handler: SpeechRequestHandler = findHandlerToHandle(request);
handler.handle(request);
}
}
class EventDispatcher {
- handle(request: EventRequest) {
handler: EventRequestHandler = findHandlerToHandle(request);
handler.handle(request);
}
}
现在,我想重构并创建一个基础/通用类。自然而然地,我想到了这个:
class Request {sessionId: String}
class SpeechRequest extends Request {slot: String}
class EventRequest extends Request {event: String}
class RequestHandler {
- canHandleRequest(Request): bool
- handle(Request)
}
class SpeechRequestHandler extends RequestHandler {
- canHandleRequest(request: Request): bool = request instanceof SpeechRequest
}
class EventRequestHandler extends RequestHandler {
- canHandleRequest(request: Request): bool = request instanceof EventRequest
}
class SpeechRequestHandler[A/B/C] extends SpeechRequestHandler {
- handle(Request: request) {
//need to cast to specific type to extract a certain fields to do some operation
//!! I feel something is not right because of that
speechRequest:SpeechRequest = (SpeechRequest)request;
doSt(speechRequest.slot)
//other operation can work with base Request object; so it's OK
}
}
class EventRequestHandler[A/B/C] extends EventRequestHandler {
- handle(Request: request) {
eventRequest:EventRequest = (EventRequest)request;
doSt(eventRequest.event)
//other operation can work with base Request object; so it's OK
}
}
对于所有SpeechRequestHandler[A/B/C]:handle函数,我现在需要将Request对象强制转换为(SpeechRequest)对象,即speechRequest:SpeechRequest = (SpeechRequest)request;。
我觉得我的设计存在缺陷。如果每个SpeechRequestHandler都需要将对象转换为(SpeechRequest),以便我可以使用这些信息,那么在这种情况下重构基类是否没有意义?
请问您能否提供更好的方法或设计模式来清洁地处理这个问题。
谢谢。
RequestHandler
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