使用 RouterFunction 在 WebFlux 中处理错误

Question

我无法让我的反应式代码以通用方式处理错误。理想的方法是在一个可重用的组件中，我可以将其作为依赖项添加到其他项目中。

以前我们都是@RestControllerAdvise用个性化的@ExceptionHandler函数来处理的。作为参考，我的代码：

@Configuration
public class VesselRouter {

    @Bean
    public RouterFunction<ServerResponse> route(VesselHandler handler) {
        return RouterFunctions.route(GET("/vessels/{imoNumber}").and(accept(APPLICATION_JSON)), handler::getVesselByImo)
                .andRoute(GET("/vessels").and(accept(APPLICATION_JSON)), handler::getVessels);
    }
}

此外，处理程序 class:

@Component
@AllArgsConstructor
public class VesselHandler {
    private VesselsService vesselsService;

    public Mono<ServerResponse> getVesselByImo(ServerRequest request) {
        String imoNumber = request.pathVariable("imoNumber");
        Mono<VesselResponse> response = this.vesselsService.getByImoNumber(imoNumber);
        return response.hasElement().flatMap(vessel -> {
                if (vessel) {
                    return ServerResponse.ok()
                            .contentType(APPLICATION_JSON)
                            .body(response, VesselResponse.class);
                } else {
                    throw new DataNotFoundException("The data you seek is not here.");
                }
            }
        );

    }

    public Mono<ServerResponse> getVessels(ServerRequest request) {
        return this.vesselsService.getAllVessels();
    }
}
/**
 * Exception class to be thrown when data not found for the requested resource
 */
public class DataNotFoundException extends RuntimeException {

    public DataNotFoundException(String e) {
        super(e);
    }
}

在我们的公共图书馆中：

@ControllerAdvice(assignableTypes={VesselHandler.class})
// FIXME: referencing class here is not good, it will create circular dependency when moved to it's own jar
@Slf4j
public class ExceptionHandlers {

    @ExceptionHandler(value = DataNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public ResponseEntity<String> handleDataNotFoundException(DataNotFoundException dataNotFoundException,
                                                                ServletWebRequest servletWebRequest) {
        //habdling expcetions code here
    }
}

还有异常处理程序：

@ControllerAdvice
@Slf4j
public class ExceptionHandlers {

    @ExceptionHandler(value = DataNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public ResponseEntity<String> handleDataNotFoundException(DataNotFoundException dataNotFoundException,
                                                                ServletWebRequest servletWebRequest) {
        //habdling expcetions code here
    }
}

我在 spring documentation 中读到，这是它应该的工作方式，但我的单元测试似乎没有在异常处理程序附近进行任何操作：

@Test
    public void findByImoNoData() {
        when(vesselsService.getByImoNumber("1234567")).thenReturn(Mono.empty());
        webTestClient.get().uri("/vessels/1234567")
                .accept(MediaType.APPLICATION_JSON)
                .exchange()
                .expectStatus().isNotFound();
    }

我也尝试过使用 AbstractErrorWebExceptionHandler 作为 Baeldung 中的示例。似乎也不起作用：

@Component
@Order(-2)
public class GlobalErrorWebExceptionHandler extends AbstractErrorWebExceptionHandler {

    public GlobalErrorWebExceptionHandler(ErrorAttributes errorAttributes, ResourceProperties resourceProperties, ApplicationContext applicationContext) {
        super(errorAttributes, resourceProperties, applicationContext);
    }

    @Override
    protected RouterFunction<ServerResponse> getRoutingFunction(
            ErrorAttributes errorAttributes) {

        return RouterFunctions.route(
                RequestPredicates.all(), this::renderErrorResponse);
    }

    private Mono<ServerResponse> renderErrorResponse(
            ServerRequest request) {

        Map<String, Object> errorPropertiesMap = getErrorAttributes(request, false);

        return ServerResponse.status(HttpStatus.BAD_REQUEST)
                .contentType(MediaType.APPLICATION_JSON_UTF8)
                .body(BodyInserters.fromObject(errorPropertiesMap));
    }
}

那么，如何在不使用 @RestController 的情况下使用 WebFlux 进行全局错误处理？

Answer 1

@ControllerAdvice 仅适用于带注释的编程模型。要使用功能端点提供 ControllerAdvice 等功能，您可以利用 HandlerFilterFunction。来自参考：

Routes mapped by a router function can be filtered by calling RouterFunction.filter(HandlerFilterFunction), where HandlerFilterFunction is essentially a function that takes a ServerRequest and HandlerFunction, and returns a ServerResponse. The handler function parameter represents the next element in the chain: this is typically the HandlerFunction that is routed to, but can also be another FilterFunction if multiple filters are applied. With annotations, similar functionality can be achieved using @ControllerAdvice and/or a ServletFilter.

@Bean
RouterFunction<ServerResponse> route() {
    return RouterFunctions
            .route(GET("/foo"), request -> Mono.error(new DataNotFoundException()))
            .andRoute(GET("/bar"), request -> Mono.error(new DataNotFoundException()))
            .filter(dataNotFoundToBadRequest());
}

private HandlerFilterFunction<ServerResponse, ServerResponse> dataNotFoundToBadRequest() {
    return (request, next) -> next.handle(request)
            .onErrorResume(DataNotFoundException.class, e -> ServerResponse.badRequest().build());
}

或者，您可以使用 WebFilter 来完成同样的事情：

@Bean
RouterFunction<ServerResponse> route() {
    return RouterFunctions
            .route(GET("/foo"), request -> Mono.error(new DataNotFoundException()))
            .andRoute(GET("/bar"), request -> Mono.error(new DataNotFoundException()));
}

@Bean
WebFilter dataNotFoundToBadRequest() {
    return (exchange, next) -> next.filter(exchange)
            .onErrorResume(DataNotFoundException.class, e -> {
                ServerHttpResponse response = exchange.getResponse();
                response.setStatusCode(HttpStatus.BAD_REQUEST);
                return response.setComplete();
            });
}

Answer 2

对我来说，我编写了一个 AppException 并将其扔到应用程序（Rest 控制器）中我认为应该是 "error" 响应的任何位置。

AppException：我的特定异常，它可以包含任何你想要处理、显示、return错误。

public class AppException extends RuntimeException {
    int code;
    HttpStatus status = HttpStatus.OK;
    ...
}

然后我定义 (a) 全局 ControllerAdvice，它负责过滤掉那些 AppExceptions。

这是我的示例，我可以取出我在 Rest Controller 中抛出的 AppException，然后 return 它作为 ReponseEntity，正文作为 "ErrorResponse" POJO。

public class ErrorResponse {

    boolean error = true;
    int code;
    String message;
}

@ControllerAdvice
public class GlobalExceptionHandlingControllerAdvice {

    @ExceptionHandler(AppException.class)
    public ResponseEntity handleAppException(AppException ex) {
        return ResponseEntity.ok(new ErrorResponse(ex.getCode(), ex.getMessage()));
    }
}

在 webflux 中，错误可能由 return Mono.error() 抛出，如 Rob Winch 的回答。

使用 RouterFunction 在 WebFlux 中处理错误

Error handling in WebFlux with RouterFunction

spring-webflux