如何根据异常定制Spring Cloud Gateway自定义异常的状态码

Question

在网关中自定义异常时，我发现无法获取异常的状态码，所以不知道如何设置自定义状态码，而不是将所有的异常状态码都设置为相同。

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Answer 1

Spring Cloud Gateway自定义处理程序异常处理程序。Spring Cloud 2020.0.3版本示例。常见的方法有你自己的defaultErrorWebexceptionHandler或者只有ErrorAttributes。

方法1: ErrorWebexceptionHandler (仅用于原理图)。自定义一个Customize属性：

@Component
public class GlobalErrorAttributes extends DefaultErrorAttributes{

    @Override
    public Map<String, Object> getErrorAttributes(ServerRequest request, ErrorAttributeOptions options) {
        Throwable error = super.getError(request);
        Map<String, Object> map = super.getErrorAttributes(request, options);
        map.put("status", HttpStatus.BAD_REQUEST.value());
        map.put("message", error.getMessage());
        return map;
    }
}

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

    public GlobalErrorWebExceptionHandler(GlobalErrorAttributes gea, ApplicationContext applicationContext,
                                          ServerCodecConfigurer serverCodecConfigurer) {
        super(gea, new WebProperties.Resources(), applicationContext);
        super.setMessageWriters(serverCodecConfigurer.getWriters());
        super.setMessageReaders(serverCodecConfigurer.getReaders());
    }

         // Rendering HTML or JSON.
    @Override
    protected RouterFunction<ServerResponse> getRoutingFunction(final ErrorAttributes errorAttributes) {
        return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
    }

    private Mono<ServerResponse> renderErrorResponse(final ServerRequest request) {
        final Map<String, Object> errorPropertiesMap = getErrorAttributes(request, ErrorAttributeOptions.defaults());
        return ServerResponse.status(HttpStatus.BAD_REQUEST)
                .contentType(MediaType.APPLICATION_JSON)
                .body(BodyInserters.fromValue(errorPropertiesMap));
    }
}

参考文档：https://docs.spring.io/spring-boot/docs/current/api/org/springframework/boot/autoconfigure/web/reactive/error/AbstractErrorWebExceptionHandler.html

方法2:仅一个ErroraTributes，覆盖默认defaultrRorattributes。

@Component
public class GatewayErrorAttributes extends DefaultErrorAttributes {

    private static final Logger logger = LoggerFactory.getLogger(GatewayErrorAttributes.class);

    @Override
    public Map<String, Object> getErrorAttributes(ServerRequest request,  ErrorAttributeOptions options) {
        Throwable error = super.getError(request);
        Map<String, Object> errorAttributes = new HashMap<>(8);
        errorAttributes.put("message", error.getMessage());
        errorAttributes.put("method", request.methodName());
        errorAttributes.put("path", request.path());
        MergedAnnotation<ResponseStatus> responseStatusAnnotation = MergedAnnotations
                .from(error.getClass(), MergedAnnotations.SearchStrategy.TYPE_HIERARCHY).get(ResponseStatus.class);
        HttpStatus errorStatus = determineHttpStatus(error, responseStatusAnnotation);
                 // Must set, otherwise an error will be reported because the RendereRRRRESPONSE method of DefaultErrorWebexceptionHandler gets this property, re-implementing defaultErrorWebexceptionHandler.
        errorAttributes.put("status", errorStatus.value());
        errorAttributes.put("code", errorStatus.value());
                 // html view
        errorAttributes.put("timestamp", new Date());
                 // html view
        errorAttributes.put("requestId", request.exchange().getRequest().getId());
        errorAttributes.put("error", errorStatus.getReasonPhrase());
        errorAttributes.put("exception", error.getClass().getName());
        return errorAttributes;
    }
         // Copy from DefaultErrorWebexceptionHandler
    private HttpStatus determineHttpStatus(Throwable error, MergedAnnotation<ResponseStatus> responseStatusAnnotation) {
        if (error instanceof ResponseStatusException) {
            return ((ResponseStatusException) error).getStatus();
        }
        return responseStatusAnnotation.getValue("code", HttpStatus.class).orElse(HttpStatus.INTERNAL_SERVER_ERROR);
    }
    
}

请注意：ErroraTributes.put ("status", errorstatus.value ())，否则会因为DefaultErrorwebexceptionHandler的rendererrorResponse方法获取此属性而报告错误。除非您像您自己一样重新实现defaultErrorWebexceptionhandler。

然后访问网关中的一个不适当的服务来查看效果。

curl 'http://127.0.0.1:8900/fundmain22/abc/gogogo?id=1000' --header 'Accept: application/json'
{"exception":"org.springframework.web.server.ResponseStatusException","path":"/fundmain22/abc/gogogo","code":404,"method":"GET","requestId":"094e53e5-1","message":"404 NOT_FOUND","error":"Not Found","status":404,"timestamp":"2021-08-09T11:07:44.106+0000"}