聊聊Spring Cloud Gateway过滤器精确控制异常返回问题

@Override
protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
		return route(acceptsTextHtml(), this::renderErrorView).andRoute(all(), this::renderErrorResponse);
	}

protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
  // 取出所有错误信息
  Map<String, Object> error = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
  
  // 构造返回的所有信息 
  return ServerResponse
           // 控制返回码
           .status(getHttpStatus(error))
           // 控制返回ContentType
           .contentType(MediaType.APPLICATION_JSON)
           // 控制返回内容
           .body(BodyInserters.fromValue(error));
}

protected int getHttpStatus(Map<String, Object> errorAttributes) {
  return (int) errorAttributes.get("status");
}

public Map<String, Object> getErrorAttributes(ServerRequest request, ErrorAttributeOptions options) {
        Map<String, Object> errorAttributes = this.getErrorAttributes(request, options.isIncluded(Include.STACK_TRACE));
        if (Boolean.TRUE.equals(this.includeException)) {
            options = options.including(new Include[]{Include.EXCEPTION});
        }

        if (!options.isIncluded(Include.EXCEPTION)) {
            errorAttributes.remove("exception");
        }

        if (!options.isIncluded(Include.STACK_TRACE)) {
            errorAttributes.remove("trace");
        }

        if (!options.isIncluded(Include.MESSAGE) && errorAttributes.get("message") != null) {
            errorAttributes.put("message", "");
        }

        if (!options.isIncluded(Include.BINDING_ERRORS)) {
            errorAttributes.remove("errors");
        }

        return errorAttributes;
    }

private HttpStatus determineHttpStatus(Throwable error, MergedAnnotation<ResponseStatus> responseStatusAnnotation) {
        // 异常对象是不是ResponseStatusException类型
        return error instanceof ResponseStatusException 
        // 如果是ResponseStatusException类型，就调用异常对象的getStatus方法作为返回值
        ? ((ResponseStatusException)error).getStatus() 
        // 如果不是ResponseStatusException类型，再看异常类有没有ResponseStatus注解，
        // 如果有，就取注解的code属性作为返回值
        : (HttpStatus)responseStatusAnnotation.getValue("code", HttpStatus.class)
        // 如果异常对象既不是ResponseStatusException类型，也没有ResponseStatus注解，就返回500
        .orElse(HttpStatus.INTERNAL_SERVER_ERROR);
    }

 private String determineMessage(Throwable error, MergedAnnotation<ResponseStatus> responseStatusAnnotation) {
        // 异常对象是不是BindingResult类型
        if (error instanceof BindingResult) {
            // 如果是，就用getMessage作为返回值
            return error.getMessage();
        } 
        // 如果不是BindingResult类型，就看是不是ResponseStatusException类型
        else if (error instanceof ResponseStatusException) {
            // 如果是，就用getReason作为返回值
            return ((ResponseStatusException)error).getReason();
        } else {
            // 如果也不是ResponseStatusException类型，
            // 就看异常类有没有ResponseStatus注解，如果有就取该注解的reason属性作为返回值
            String reason = (String)responseStatusAnnotation.getValue("reason", String.class).orElse("");
            if (StringUtils.hasText(reason)) {
                return reason;
            } else {
                // 如果通过注解取得的reason也无效，就返回异常的getMessage字段
                return error.getMessage() != null ? error.getMessage() : "";
            }
        }
    }