Exception : PreFlightHandler can not casting

Spring Interceptor에서 PreFlight Request (CORS 인식을 위한 OPTIONS 요청)에 대해서 HandlerMethod로 케스팅 한 경우 발생.

해결 방법은 instanceof로 체크 하면 됨

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관련 자료)






PreFlightHandler 클래스 

private class PreFlightHandler implements HttpRequestHandler {

 private final CorsConfiguration config;

 public PreFlightHandler(CorsConfiguration config) {

  this.config = config;

 }

 @Override

 public void handleRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {

  corsProcessor.processRequest(this.config, request, response);

 }

}

PreFlightHandler를 사용하는 메소드

AbstractHandlerMapping.getCorsHandlerExecutionChain

Update the HandlerExecutionChain for CORS-related handling.

For pre-flight requests, the default implementation replaces the selected handler with a simple HttpRequestHandler that invokes the configured setCorsProcessor(org.springframework.web.cors.CorsProcessor).

For actual requests, the default implementation inserts a HandlerInterceptor that makes CORS-related checks and adds CORS headers.


pre-flight requests는 무엇인가?


https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request



A CORS preflight request is a CORS request that checks to see if the CORS protocol is understood and a server is aware using specific methods and headers.

It is an OPTIONS request, using three HTTP request headers: Access-Control-Request-Method, Access-Control-Request-Headers, and the Origin header.

A preflight request is automatically issued by a browser and in normal cases, front-end developers don't need to craft such requests themselves. It appears when request is qualified as "to be preflighted" and ommited for simple requests.

For example, a client might be asking a server if it would allow a DELETE request, before sending a DELETE request, by using a preflight request: