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聊聊spring cloud gateway的GatewayFilter

go4it
 go4it
发布于 06/09 22:08
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本文主要研究一下spring cloud gateway的GatewayFilter

GatewayFilter

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/GatewayFilter.java

/**
 * Contract for interception-style, chained processing of Web requests that may
 * be used to implement cross-cutting, application-agnostic requirements such
 * as security, timeouts, and others. Specific to a Gateway
 *
 * Copied from WebFilter
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public interface GatewayFilter extends ShortcutConfigurable {

	String NAME_KEY = "name";
	String VALUE_KEY = "value";

	/**
	 * Process the Web request and (optionally) delegate to the next
	 * {@code WebFilter} through the given {@link GatewayFilterChain}.
	 * @param exchange the current server exchange
	 * @param chain provides a way to delegate to the next filter
	 * @return {@code Mono<Void>} to indicate when request processing is complete
	 */
	Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);

}

如注释所说,主要用于类似切面的非功能性需求,比如安全、超时控制等。其直接的实现类为OrderedGatewayFilter、ModifyResponseGatewayFilter、GatewayFilterAdapter

OrderedGatewayFilter

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/OrderedGatewayFilter.java

public class OrderedGatewayFilter implements GatewayFilter, Ordered {

	private final GatewayFilter delegate;
	private final int order;

	public OrderedGatewayFilter(GatewayFilter delegate, int order) {
		this.delegate = delegate;
		this.order = order;
	}

	public GatewayFilter getDelegate() {
		return delegate;
	}

	@Override
	public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
		return this.delegate.filter(exchange, chain);
	}

	@Override
	public int getOrder() {
		return this.order;
	}

	@Override
	public String toString() {
		final StringBuilder sb = new StringBuilder("OrderedGatewayFilter{");
		sb.append("delegate=").append(delegate);
		sb.append(", order=").append(order);
		sb.append('}');
		return sb.toString();
	}
}

实现了Order接口

ModifyResponseGatewayFilter

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/rewrite/ModifyResponseBodyGatewayFilterFactory.java

	public class ModifyResponseGatewayFilter implements GatewayFilter, Ordered {
		private final Config config;

		public ModifyResponseGatewayFilter(Config config) {
			this.config = config;
		}

		@Override
		@SuppressWarnings("unchecked")
		public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
			ServerHttpResponseDecorator responseDecorator = new ServerHttpResponseDecorator(exchange.getResponse()) {
				@Override
				public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {

					ResolvableType inElementType = ResolvableType.forClass(config.getInClass());
					ResolvableType outElementType = ResolvableType.forClass(config.getOutClass());
					MediaType contentType = exchange.getResponse().getHeaders().getContentType();
					Optional<HttpMessageReader<?>> reader = getHttpMessageReader(codecConfigurer, inElementType, contentType);
					Optional<HttpMessageWriter<?>> writer = getHttpMessageWriter(codecConfigurer, outElementType, null);

					if (reader.isPresent() && writer.isPresent()) {

						ResponseAdapter responseAdapter = new ResponseAdapter(body, getDelegate().getHeaders());

						Flux<?> modified = reader.get().read(inElementType, responseAdapter, config.getInHints())
								.cast(inElementType.resolve())
								.flatMap(originalBody -> Flux.just(config.rewriteFunction.apply(exchange, originalBody)))
								.cast(outElementType.resolve());

						return getDelegate().writeWith(
								writer.get().write((Publisher)modified, outElementType, null, getDelegate(),
										config.getOutHints())
						);

					}
					// TODO: error? log?

					return getDelegate().writeWith(body);
				}

				@Override
				public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {
					return writeWith(Flux.from(body)
							.flatMapSequential(p -> p));
				}
			};

			return chain.filter(exchange.mutate().response(responseDecorator).build());
		}

		@Override
		public int getOrder() {
			return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 1;
		}

	}

主要用于修改response

GatewayFilterAdapter

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/handler/FilteringWebHandler.java

	private static class GatewayFilterAdapter implements GatewayFilter {

		private final GlobalFilter delegate;

		public GatewayFilterAdapter(GlobalFilter delegate) {
			this.delegate = delegate;
		}

		@Override
		public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
			return this.delegate.filter(exchange, chain);
		}

		@Override
		public String toString() {
			final StringBuilder sb = new StringBuilder("GatewayFilterAdapter{");
			sb.append("delegate=").append(delegate);
			sb.append('}');
			return sb.toString();
		}
	}

将GlobalFilter转为GatewayFilter的适配器

GatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/GatewayFilterFactory.java

@FunctionalInterface
public interface GatewayFilterFactory<C> extends ShortcutConfigurable, Configurable<C> {

	String NAME_KEY = "name";
	String VALUE_KEY = "value";

	// useful for javadsl
	default GatewayFilter apply(Consumer<C> consumer) {
		C config = newConfig();
		consumer.accept(config);
		return apply(config);
	}

	default Class<C> getConfigClass() {
		throw new UnsupportedOperationException("getConfigClass() not implemented");
	}

	@Override
	default C newConfig() {
		throw new UnsupportedOperationException("newConfig() not implemented");
	}

	GatewayFilter apply(C config);

	default String name() {
		//TODO: deal with proxys
		return NameUtils.normalizeFilterFactoryName(getClass());
	}

	@Deprecated
	default ServerHttpRequest.Builder mutate(ServerHttpRequest request) {
		return request.mutate();
	}
}

spring cloud gateway采用工厂模式来生成GatewayFilter,可以看到这里定义了apply方法,根据config来生成GatewayFilter。GatewayFilterFactory有几个抽象类,分别是AbstractGatewayFilterFactory、AbstractNameValueGatewayFilterFactory(继承了AbstractGatewayFilterFactory)、AbstractChangeRequestUriGatewayFilterFactory。

AbstractGatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/AbstractGatewayFilterFactory.java

public abstract class AbstractGatewayFilterFactory<C>
		extends AbstractConfigurable<C> implements GatewayFilterFactory<C> {

	@SuppressWarnings("unchecked")
	public AbstractGatewayFilterFactory() {
		super((Class<C>) Object.class);
	}

	public AbstractGatewayFilterFactory(Class<C> configClass) {
		super(configClass);
	}

	public static class NameConfig {
		private String name;

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}
	}
}

它的直接实现类如下:

  • HystrixGatewayFilterFactory
  • ModifyRequestBodyGatewayFilterFactory
  • ModifyResponseBodyGatewayFilterFactory
  • PrefixPathGatewayFilterFactory
  • PreserveHostHeaderGatewayFilterFactory
  • RedirectToGatewayFilterFactory
  • RemoveRequestHeaderGatewayFilterFactory
  • RemoveResponseHeaderGatewayFilterFactory
  • RequestRateLimiterGatewayFilterFactory
  • RetryGatewayFilterFactory
  • RewritePathGatewayFilterFactory
  • SaveSessionGatewayFilterFactory
  • SecureHeadersGatewayFilterFactory
  • SetPathGatewayFilterFactory
  • SetStatusGatewayFilterFactory
  • StripPrefixGatewayFilterFactory

AbstractNameValueGatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/AbstractNameValueGatewayFilterFactory.java

public abstract class AbstractNameValueGatewayFilterFactory extends AbstractGatewayFilterFactory<AbstractNameValueGatewayFilterFactory.NameValueConfig> {

	public AbstractNameValueGatewayFilterFactory() {
		super(NameValueConfig.class);
	}

	public List<String> shortcutFieldOrder() {
        return Arrays.asList(GatewayFilter.NAME_KEY, GatewayFilter.VALUE_KEY);
    }


	@Validated
	public static class NameValueConfig {
		@NotEmpty
		protected String name;
		@NotEmpty
		protected String value;

		public String getName() {
			return name;
		}

		public NameValueConfig setName(String name) {
			this.name = name;
			return this;
		}

		public String getValue() {
			return value;
		}

		public NameValueConfig setValue(String value) {
			this.value = value;
			return this;
		}

		@Override
		public String toString() {
			return new ToStringCreator(this)
					.append("name", name)
					.append("value", value)
					.toString();
		}
	}
}

将泛型限定为AbstractNameValueGatewayFilterFactory.NameValueConfig,其实现类如下:

  • AddRequestHeaderGatewayFilterFactory
  • AddRequestParameterGatewayFilterFactory
  • AddResponseHeaderGatewayFilterFactory
  • SetRequestHeaderGatewayFilterFactory
  • SetResponseHeaderGatewayFilterFactory

AbstractChangeRequestUriGatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/AbstractChangeRequestUriGatewayFilterFactory.java

/**
 * This filter changes the request uri by
 * {@link #determineRequestUri(ServerWebExchange, T)} logic.
 *
 * @author Toshiaki Maki
 */
public abstract class AbstractChangeRequestUriGatewayFilterFactory<T>
		extends AbstractGatewayFilterFactory<T> {
	private final int order;

	public AbstractChangeRequestUriGatewayFilterFactory(Class<T> clazz, int order) {
		super(clazz);
		this.order = order;
	}

	public AbstractChangeRequestUriGatewayFilterFactory(Class<T> clazz) {
		this(clazz, RouteToRequestUrlFilter.ROUTE_TO_URL_FILTER_ORDER + 1);
	}

	protected abstract Optional<URI> determineRequestUri(ServerWebExchange exchange,
			T config);

	public GatewayFilter apply(T config) {
		return new OrderedGatewayFilter((exchange, chain) -> {
			Optional<URI> uri = this.determineRequestUri(exchange, config);
			uri.ifPresent(u -> {
				Map<String, Object> attributes = exchange.getAttributes();
				attributes.put(GATEWAY_REQUEST_URL_ATTR, u);
			});
			return chain.filter(exchange);
		}, this.order);
	}
}

通过GATEWAY_REQUEST_URL_ATTR设置新的uri,其直接实现类为

  • RequestHeaderToRequestUriGatewayFilterFactory(通过header的值来设定uri)

GatewayFilterFactory.apply

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/route/RouteDefinitionRouteLocator.java

	private List<GatewayFilter> loadGatewayFilters(String id, List<FilterDefinition> filterDefinitions) {
		List<GatewayFilter> filters = filterDefinitions.stream()
				.map(definition -> {
					GatewayFilterFactory factory = this.gatewayFilterFactories.get(definition.getName());
					if (factory == null) {
                        throw new IllegalArgumentException("Unable to find GatewayFilterFactory with name " + definition.getName());
					}
					Map<String, String> args = definition.getArgs();
					if (logger.isDebugEnabled()) {
						logger.debug("RouteDefinition " + id + " applying filter " + args + " to " + definition.getName());
					}

                    Map<String, Object> properties = factory.shortcutType().normalize(args, factory, this.parser, this.beanFactory);

                    Object configuration = factory.newConfig();

                    ConfigurationUtils.bind(configuration, properties,
                            factory.shortcutFieldPrefix(), definition.getName(), validator);

                    GatewayFilter gatewayFilter = factory.apply(configuration);
                    if (this.publisher != null) {
                        this.publisher.publishEvent(new FilterArgsEvent(this, id, properties));
                    }
                    return gatewayFilter;
				})
				.collect(Collectors.toList());

		ArrayList<GatewayFilter> ordered = new ArrayList<>(filters.size());
		for (int i = 0; i < filters.size(); i++) {
			GatewayFilter gatewayFilter = filters.get(i);
			if (gatewayFilter instanceof Ordered) {
				ordered.add(gatewayFilter);
			}
			else {
				ordered.add(new OrderedGatewayFilter(gatewayFilter, i + 1));
			}
		}

		return ordered;
	}

这里通过factory去实例化每个route的GatewayFilter

小结

spring cloud gateway的GatewayFilter主要是通过GatewayFilterFactory来生产的。而GatewayFilterFactory主要有三个抽象类:

  • AbstractGatewayFilterFactory
    • HystrixGatewayFilterFactory
    • ModifyRequestBodyGatewayFilterFactory
    • ModifyResponseBodyGatewayFilterFactory
    • PrefixPathGatewayFilterFactory
    • PreserveHostHeaderGatewayFilterFactory
    • RedirectToGatewayFilterFactory
    • RemoveRequestHeaderGatewayFilterFactory
    • RemoveResponseHeaderGatewayFilterFactory
    • RequestRateLimiterGatewayFilterFactory
    • RetryGatewayFilterFactory
    • RewritePathGatewayFilterFactory
    • SaveSessionGatewayFilterFactory
    • SecureHeadersGatewayFilterFactory
    • SetPathGatewayFilterFactory
    • SetStatusGatewayFilterFactory
    • StripPrefixGatewayFilterFactory
  • AbstractNameValueGatewayFilterFactory(继承了AbstractGatewayFilterFactory)
    • AddRequestHeaderGatewayFilterFactory
    • AddRequestParameterGatewayFilterFactory
    • AddResponseHeaderGatewayFilterFactory
    • SetRequestHeaderGatewayFilterFactory
    • SetResponseHeaderGatewayFilterFactory
  • AbstractChangeRequestUriGatewayFilterFactory
    • RequestHeaderToRequestUriGatewayFilterFactory

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