无法使用 Webflux authenticationFailureHandler 返回 JSON 数据答案

【问题标题】：Unable to return JSON data with Webflux authenticationFailureHandler无法使用 Webflux authenticationFailureHandler 返回 JSON 数据
【发布时间】：2019-07-05 02:01:36
【问题描述】：

我正在构建一个 React SPA，并希望使用 JSON 与后端进行交互。当身份验证失败时，我希望能够以 JSON 的形式发送自定义错误消息。但是给出下面的代码：

    .authenticationFailureHandler(((exchange, e) -> {
      return Mono.fromRunnable(() -> {
        ServerHttpResponse response = exchange.getExchange().getResponse();
        response.setStatusCode(HttpStatus.OK);
        response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
        DataBuffer buf = exchange.getExchange().getResponse().bufferFactory().wrap("{\"test\":\"tests\"}".getBytes(StandardCharsets.UTF_8));
        response.writeWith(Mono.just(buf));
      });
    })

我收到以下错误：

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-XSS-Protection: 1 ; mode=block
Referrer-Policy: no-referrer
content-length: 0

<Response body is empty>

Response code: 200 (OK); Time: 1162ms; Content length: 0 bytes

但是，如果我更改响应代码，它会反映在响应中，因此我知道代码已执行但没有返回响应正文。

当身份验证失败时，我需要更改哪些内容才能发回响应正文？

【问题讨论】：

标签： java spring-boot spring-security spring-webflux

【解决方案1】：

我认为这可行：

.authenticationFailureHandler(((exchange, e) -> {
        ServerHttpResponse response = exchange.getExchange().getResponse();
        response.setStatusCode(HttpStatus.OK);
        response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
        DataBuffer buf = exchange.getExchange().getResponse().bufferFactory().wrap("{\"test\":\"tests\"}".getBytes(StandardCharsets.UTF_8));
        return response.writeWith(Mono.just(buf));
      });
    })

可能有比将 JSON 写为字符串更好的方法，但我相信这应该可行。您的尝试没有奏效，因为没有订阅 response.writeWith(Mono.just(buf)) 返回的 Publisher。由于发布者很懒惰，因此不会向响应中写入任何内容。

【讨论】：

【解决方案2】：

您也可以通过自定义 WebExceptionHandler 和 ErrorAttributes 来实现此目的

.authenticationFailureHandler(webFilterExchange, exception) ->
     customErrorWebExceptionHandler.handle(webFilterExchange.getExchange(), exception);


@Component
public class CustomErrorWebExceptionHandler extends AbstractErrorWebExceptionHandler {

    public CustomErrorWebExceptionHandler(
            final CustomErrorAttributes customAttributes,
            final ResourceProperties resourceProperties,
            final ObjectProvider<List<ViewResolver>> viewResolversProvider,
            final ServerCodecConfigurer serverCodecConfigurer,
            final ApplicationContext applicationContext
    ) {
        super(customAttributes, resourceProperties, applicationContext);

        this.setViewResolvers(viewResolversProvider.getIfAvailable(Collections::emptyList));
        this.setMessageWriters(serverCodecConfigurer.getWriters());
        this.setMessageReaders(serverCodecConfigurer.getReaders());
    }

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

        if (errorAttributes instanceof CustomErrorAttributes) {
            return RouterFunctions.route(RequestPredicates.all(),
                (request) -> handleProblemDetail(request, (CustomErrorAttributes) errorAttributes)
                        );
        }
        throw new UnsupportedOperationException(errorAttributes.getClass().getName());
    }

    private Mono<ServerResponse> handleProblemDetail(final ServerRequest request, final CustomErrorAttributes error) {

        final Map<String, Object> errorAttributes = error.getErrorAttributes(request, false);

        return ServerResponse.status(Integer.parseInt(errorAttributes
                .getOrDefault("status", "500").toString()))
                .contentType(MediaType.APPLICATION_PROBLEM_JSON)
                .body(Mono.just(errorAttributes), Map.class)

                ;
    }
}


@Component
public class CustomErrorAttributes implements ErrorAttributes {
    private static final String ERROR_ATTRIBUTE = CustomErrorAttributes.class.getName() + ".ERROR";

    @Override
    public Map<String, Object> getErrorAttributes(final ServerRequest request, final boolean includeStackTrace) {

        final Throwable error = this.getError(request);

        return somethingThatConvertsTheErrorToAMap(error);
    }

    @Override
    public Throwable getError(final ServerRequest request) {
        return (Throwable)request.attribute(ERROR_ATTRIBUTE).orElseThrow(() -> {
            return new IllegalStateException("Missing exception attribute in ServerWebExchange");
        });
    }

    @Override
    public void storeErrorInformation(final Throwable error, final ServerWebExchange exchange) {
        exchange.getAttributes().putIfAbsent(ERROR_ATTRIBUTE, error);
    }
}

【讨论】：