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本文主要研究下spring cloud gateway的SetStatusGatewayFilter

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 {//......@Beanpublic SetStatusGatewayFilterFactory setStatusGatewayFilterFactory() {return new SetStatusGatewayFilterFactory();}//......
}

默认创建SetStatusGatewayFilterFactory

SetStatusGatewayFilterFactory

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

public class SetStatusGatewayFilterFactory extends AbstractGatewayFilterFactory<SetStatusGatewayFilterFactory.Config> {public static final String STATUS_KEY = "status";public SetStatusGatewayFilterFactory() {super(Config.class);}@Overridepublic List<String> shortcutFieldOrder() {return Arrays.asList(STATUS_KEY);}@Overridepublic GatewayFilter apply(Config config) {final HttpStatus status = ServerWebExchangeUtils.parse(config.status);final Integer intStatus;if (status == null) {intStatus = Integer.parseInt(config.status);} else {intStatus = null;}return (exchange, chain) -> {// option 1 (runs in filter order)/*exchange.getResponse().beforeCommit(() -> {exchange.getResponse().setStatusCode(finalStatus);return Mono.empty();});return chain.filter(exchange);*/// option 2 (runs in reverse filter order)return chain.filter(exchange).then(Mono.fromRunnable(() -> {// check not really needed, since it is guarded in setStatusCode,// but it's a good exampleif (!exchange.getResponse().isCommitted()) {if (status != null) { // standard statussetResponseStatus(exchange, status);} else if (intStatus != null && exchange.getResponse() instanceof AbstractServerHttpResponse) { //non-standard((AbstractServerHttpResponse)exchange.getResponse()).setStatusCodeValue(intStatus);}}}));};}public static class Config {//TODO: relaxed HttpStatus converterprivate String status;public String getStatus() {return status;}public void setStatus(String status) {this.status = status;}}}

• 可以看到，就是简单地根据status来设置response的status
• 注意这里有两个option，源码注释掉了option1，改为使用option2

实例

spring:cloud:gateway:routes:- id: setstatusstring_routeuri: http://example.orgpredicates:- Path=/foo/**filters:- SetStatus=BAD_REQUEST- id: setstatusint_routeuri: http://example.orgpredicates:- Path=/name/**filters:- SetStatus=401

小结

SetStatusGatewayFilter就是简单地设置response，使用option1方式的话，是在response commit之前设置的，而且一旦设置就直接return，不再继续走filter了，因而SetStatus可以生效；使用option2的话，是逆filter顺序执行的，会先判断是否commit，未commit才设置，实际不生效。

doc

• 112.17 SetStatus GatewayFilter Factory