聊聊spring cloud gateway的RedirectToGatewayFilter

序

本文主要研究下spring cloud gateway的RedirectToGatewayFilter

GatewayAutoConfiguration

spring-cloud-gateway-core-2.0.0.RC2-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 RedirectToGatewayFilterFactory redirectToGatewayFilterFactory() {
		return new RedirectToGatewayFilterFactory();
	}
    //......
}

RedirectToGatewayFilterFactory

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

public class RedirectToGatewayFilterFactory extends AbstractGatewayFilterFactory<RedirectToGatewayFilterFactory.Config> {

	public static final String STATUS_KEY = "status";
	public static final String URL_KEY = "url";

	public RedirectToGatewayFilterFactory() {
		super(Config.class);
	}

	@Override
	public List<String> shortcutFieldOrder() {
		return Arrays.asList(STATUS_KEY, URL_KEY);
	}

	@Override
	public GatewayFilter apply(Config config) {
		return apply(config.status, config.url);
	}

	public GatewayFilter apply(String statusString, String urlString) {
		final HttpStatus httpStatus = parse(statusString);
		Assert.isTrue(httpStatus.is3xxRedirection(), "status must be a 3xx code, but was " + statusString);
		final URL url;
		try {
			url = URI.create(urlString).toURL();
		} catch (MalformedURLException e) {
			throw new IllegalArgumentException("Invalid url " + urlString, e);
		}
		return apply(httpStatus, url);
	}

	public GatewayFilter apply(HttpStatus httpStatus, URL url) {

		return (exchange, chain) ->
			chain.filter(exchange).then(Mono.defer(() -> {
				if (!exchange.getResponse().isCommitted()) {
					setResponseStatus(exchange, httpStatus);

					final ServerHttpResponse response = exchange.getResponse();
					response.getHeaders().set(HttpHeaders.LOCATION, url.toString());
					return response.setComplete();
				}
				return Mono.empty();
			}));
	}

	public static class Config {
		String status;
		String url;

		public String getStatus() {
			return status;
		}

		public void setStatus(String status) {
			this.status = status;
		}

		public String getUrl() {
			return url;
		}

		public void setUrl(String url) {
			this.url = url;
		}
	}

}

• 能夠看到配置文件有兩個參數，一個是status，一個是url
• 這裏對status進行了校驗，必須是3xx
• 而後設置response status code，同時在header的location寫入要跳轉的url

實例

spring:
  cloud:
    gateway:
      routes:
      - id: prefixpath_route
        uri: http://example.org
        filters:
        - RedirectTo=302, http://acme.org

小結

spring cloud gateway提供了RedirectToGatewayFilter，能夠直接在配置文件對指定的路由進行3xx跳轉。

doc

• 112.8 RedirectTo GatewayFilter Factory