如果授权标头不存在，则无法在 Webfilter 中发送自定义正文

Question

我正在尝试使用 Webfilter 拦截 Spring Boot Webflux 应用程序（Spring boot 2.0.0.M7）中的所有请求，并检查“Authorization”标头是否存在。如果不存在，我想停止请求处理并发送自定义 HttpStatus 和自定义正文。自定义 HttpStatus 正在运行，但我无法将自定义消息写入 HTTP 正文。以下

import java.time.LocalDateTime;

import org.apache.commons.lang.SerializationUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.web.reactive.function.client.WebClient;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;
import reactor.util.context.Context;

public class RequestContextFilter implements WebFilter{

    Logger LOG = LoggerFactory.getLogger(RequestContextFilter.class);

    @Autowired
    private WebClient.Builder webclientBuilder;


    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        LOG.debug("Inside RequestContextFilter.."+ exchange);
        String authorizationHeader = exchange.getRequest().getHeaders().getFirst(HttpHeaders.AUTHORIZATION);
        if(authorizationHeader == null) {
            exchange.getResponse().setStatusCode(HttpStatus.BAD_REQUEST);
            ApiError apiError = new ApiError(HttpStatus.BAD_REQUEST);
            apiError.setMessage("Missing Authorization Header");
            apiError.setTimestamp(LocalDateTime.now());
   // The below code of writing to body is NOT WORKING
            exchange.getResponse().writeWith(Mono.just(new DefaultDataBufferFactory().wrap(SerializationUtils.serialize(apiError))));
            return Mono.empty();
        }
        return chain.filter(exchange);

    }


}

ApiError.java 类只不过是我想包含在响应中的自定义对象。

public class ApiError  implements Serializable{

       private HttpStatus status;
       @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy hh:mm:ss")
       private LocalDateTime timestamp;
       private String message;
       private String debugMessage;
       private List<ApiSubError> subErrors;


       public ApiError() {
           timestamp = LocalDateTime.now();
       }

       public ApiError(HttpStatus status) {
           this();
           this.status = status;
       }

       public ApiError(HttpStatus status, Throwable ex) {
           this();
           this.status = status;
           this.message = "Unexpected error";
           this.debugMessage = ex.getLocalizedMessage();
       }

       public ApiError(HttpStatus status, String message, Throwable ex) {
           this();
           this.status = status;
           this.message = message;
           this.debugMessage = ex.getLocalizedMessage();
       }





}

我卷曲了端点，这个 Webfilter 确实有效，它发送了正确的 HttpStatus 代码 400，但没有 ApiError。

请求（无授权标头）：

curl -X GET "http://localhost:8080/accounts"--verbose

回复：

HTTP/1.1 400 Bad Request
content-length: 0

状态有效并且正在调用过滤器但没有对象响应。在使用 jackson 将原始字节转换为 JSON 后，我确实尝试将字节写入 DataBufferFactory，但它不起作用。

Answer 1

+1 @bsamartins 所说的。

现在关于您的特定解决方案：该writeWith方法返回一个Publisher. 如果没有任何东西订阅它，那么什么都不会发生。你应该更换

exchange.getResponse().writeWith(Mono.just(new DefaultDataBufferFactory().wrap(SerializationUtils.serialize(apiError))));
return Mono.empty();

和

return exchange.getResponse()
               .writeWith(Mono.just(new DefaultDataBufferFactory().wrap(SerializationUtils.serialize(apiError))));

有了这个更改，Spring WebFlux 将订阅返回的内容Publisher，您的代码将写入响应。