聊聊spring cloud gateway的RemoveHopByHopHeadersFilter-白红宇

序

本文主要研究一下spring cloud gateway的RemoveHopByHopHeadersFilter

GatewayAutoConfiguration

spring-cloud-gateway-core-2.0.0.RC1-sources.jar!/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@Configuration@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)@EnableConfigurationProperties@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})@ConditionalOnClass(DispatcherHandler.class)public class GatewayAutoConfiguration {    //......    @Bean	public RemoveHopByHopHeadersFilter removeHopByHopHeadersFilter() {		return new RemoveHopByHopHeadersFilter();	}    //......}复制代码

可以看到这里自动new了一个RemoveHopByHopHeadersFilter

RemoveHopByHopHeadersFilter

spring-cloud-gateway-core-2.0.0.RC1-sources.jar!/org/springframework/cloud/gateway/filter/headers/RemoveHopByHopHeadersFilter.java

@ConfigurationProperties("spring.cloud.gateway.filter.remove-hop-by-hop")public class RemoveHopByHopHeadersFilter implements HttpHeadersFilter, Ordered {	public static final Set
    
      HEADERS_REMOVED_ON_REQUEST =			new HashSet<>(Arrays.asList(					"connection",					"keep-alive",					"transfer-encoding",					"te",					"trailer",					"proxy-authorization",					"proxy-authenticate",					"x-application-context",					"upgrade"					// these two are not listed in https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-7.1.3					//"proxy-connection",					// "content-length",					));	private int order = Ordered.LOWEST_PRECEDENCE;	private Set
     
       headers = HEADERS_REMOVED_ON_REQUEST;	public Set
      
        getHeaders() {		return headers;	}	public void setHeaders(Set
       
         headers) {		this.headers = headers;	}	@Override	public int getOrder() {		return order;	}	public void setOrder(int order) {		this.order = order;	}	@Override	public HttpHeaders filter(HttpHeaders input, ServerWebExchange exchange) {		HttpHeaders filtered = new HttpHeaders();				input.entrySet().stream()				.filter(entry -> !this.headers.contains(entry.getKey().toLowerCase()))				.forEach(entry -> filtered.addAll(entry.getKey(), entry.getValue()));		return filtered;	}	@Override 	public boolean supports(Type type) {		return type.equals(Type.REQUEST) ||				type.equals(Type.RESPONSE);	}}复制代码

可以看到这个filter是移除request或response中指定的header，默认移除的header包括"connection","keep-alive", "transfer-encoding","te","trailer","proxy-authorization","proxy-authenticate","x-application-context","upgrade"。也可以自己在配置文件指定要移除的header

配置

spring-cloud-gateway-core-2.0.0.RC1.jar!/META-INF/spring-configuration-metadata.json

{      "sourceType": "org.springframework.cloud.gateway.filter.headers.RemoveHopByHopHeadersFilter",      "name": "spring.cloud.gateway.filter.remove-hop-by-hop.headers",      "type": "java.util.Set
    
     "    },    {      "sourceType": "org.springframework.cloud.gateway.filter.headers.RemoveHopByHopHeadersFilter",      "name": "spring.cloud.gateway.filter.remove-hop-by-hop.order",      "type": "java.lang.Integer"    }复制代码

可以看到，有个order属性用来指定该filter的优先级，默认是Ordered.LOWEST_PRECEDENCE 还有另外一个属性headers，用来指定要移除的header

实例

spring:  cloud:    gateway:      filter:        remove-hop-by-hop:          headers:            - x-route            - x-auth-id复制代码

使用

spring-cloud-gateway-core-2.0.0.RC1-sources.jar!/org/springframework/cloud/gateway/filter/NettyRoutingFilter.java

public class NettyRoutingFilter implements GlobalFilter, Ordered {	private final HttpClient httpClient;	private final ObjectProvider
    
     
      > headersFilters;	public NettyRoutingFilter(HttpClient httpClient,			ObjectProvider
      
       
        > headersFilters) {		this.httpClient = httpClient;		this.headersFilters = headersFilters;	}	@Override	public int getOrder() {		return Ordered.LOWEST_PRECEDENCE;	}	@Override	public Mono
        
          filter(ServerWebExchange exchange, GatewayFilterChain chain) {		URI requestUrl = exchange.getRequiredAttribute(GATEWAY_REQUEST_URL_ATTR);		String scheme = requestUrl.getScheme();		if (isAlreadyRouted(exchange) || (!"http".equals(scheme) && !"https".equals(scheme))) {			return chain.filter(exchange);		}		setAlreadyRouted(exchange);		ServerHttpRequest request = exchange.getRequest();		final HttpMethod method = HttpMethod.valueOf(request.getMethod().toString());		final String url = requestUrl.toString();		HttpHeaders filtered = filterRequest(this.headersFilters.getIfAvailable(),				exchange);		final DefaultHttpHeaders httpHeaders = new DefaultHttpHeaders();		filtered.forEach(httpHeaders::set);		String transferEncoding = request.getHeaders().getFirst(HttpHeaders.TRANSFER_ENCODING);		boolean chunkedTransfer = "chunked".equalsIgnoreCase(transferEncoding);		boolean preserveHost = exchange.getAttributeOrDefault(PRESERVE_HOST_HEADER_ATTRIBUTE, false);		return this.httpClient.request(method, url, req -> {			final HttpClientRequest proxyRequest = req.options(NettyPipeline.SendOptions::flushOnEach)					.headers(httpHeaders)					.chunkedTransfer(chunkedTransfer)					.failOnServerError(false)					.failOnClientError(false);			if (preserveHost) {				String host = request.getHeaders().getFirst(HttpHeaders.HOST);				proxyRequest.header(HttpHeaders.HOST, host);			}			return proxyRequest.sendHeaders() //I shouldn't need this					.send(request.getBody().map(dataBuffer ->							((NettyDataBuffer)dataBuffer).getNativeBuffer()));		}).doOnNext(res -> {			ServerHttpResponse response = exchange.getResponse();			// put headers and status so filters can modify the response			HttpHeaders headers = new HttpHeaders();						res.responseHeaders().forEach(entry -> headers.add(entry.getKey(), entry.getValue()));			HttpHeaders filteredResponseHeaders = HttpHeadersFilter.filter(					this.headersFilters.getIfAvailable(), headers, exchange, Type.RESPONSE);						response.getHeaders().putAll(filteredResponseHeaders);			HttpStatus status = HttpStatus.resolve(res.status().code());			if (status != null) {				response.setStatusCode(status);			} else if (response instanceof AbstractServerHttpResponse) {				// https://jira.spring.io/browse/SPR-16748				((AbstractServerHttpResponse) response).setStatusCodeValue(res.status().code());			} else {				throw new IllegalStateException("Unable to set status code on response: " +res.status().code()+", "+response.getClass());			}			// Defer committing the response until all route filters have run			// Put client response as ServerWebExchange attribute and write response later NettyWriteResponseFilter			exchange.getAttributes().put(CLIENT_RESPONSE_ATTR, res);		}).then(chain.filter(exchange));	}}复制代码

这里头对于request，调用的是

HttpHeaders filtered = filterRequest(this.headersFilters.getIfAvailable(),				exchange);复制代码

对于response调用的是

HttpHeaders filteredResponseHeaders = HttpHeadersFilter.filter(					this.headersFilters.getIfAvailable(), headers, exchange, Type.RESPONSE);复制代码

小结

RemoveHopByHopHeadersFilter可以用来移除指定的header，其作用于request及response。

序

GatewayAutoConfiguration

RemoveHopByHopHeadersFilter

配置

使用

小结

doc