Spring Cloud Gateway：在路径中使用查询参数值？

问题描述

在Spring Cloud Gateway中，是否可以采用查询参数的值并将其用于目标的路径？

例如

/inbound/path?someId=123

导致通话

/outbound/123/detail

我尝试了以下操作：

predicates:
  - Path=/inbound/path
  - Query=someId,(?<theId>/?.*)
filters:
  - SetPath=/outbound/{theId}/detail

predicates:
  - Path=/inbound/path
  - Query=someId,{theId}
filters:
  - SetPath=/outbound/{theId}/detail

predicates:
  - Path=/inbound/path
filters:
  - RewritePath=/inbound/path?someId=(?<theId>/?.*) /outbound/$\{theId}/detail

解决方法

我写了一个自定义的路由谓词来做到这一点。

配置：

predicates:
  - Path=/inbound/path
  - QueryParam=someId
filters:
  - SetPath=/outbound/{someId}/detail

自定义代码：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.gateway.handler.predicate.AbstractRoutePredicateFactory;
import org.springframework.cloud.gateway.handler.predicate.GatewayPredicate;
import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.server.ServerWebExchange;

import javax.validation.constraints.NotEmpty;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.function.Predicate;

/**
 * Shamelessly inspired by QueryRoutePredicateFactory
 * This will store the first value of the query parameter as a template variable under the same name
 */
public class QueryParamRoutePredicateFactory extends AbstractRoutePredicateFactory<QueryParamRoutePredicateFactory.Config> {

    public static final String PARAM_KEY = "param";
    private final Logger logger = LoggerFactory.getLogger(getClass());

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

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

    @Override
    public Predicate<ServerWebExchange> apply(QueryParamRoutePredicateFactory.Config config) {
        return new GatewayPredicate() {
            @Override
            public boolean test(ServerWebExchange exchange) {
                if (exchange.getRequest().getQueryParams().containsKey(config.param)) {
                    String value = exchange.getRequest().getQueryParams().getFirst(config.param);
                    logger.debug("Saving {}={}",config.param,value);
                    ServerWebExchangeUtils.putUriTemplateVariables(exchange,Map.of(config.param,value));
                    return true;
                }
                logger.debug("Query parameter {} not found.",config.param);
                return false;
            }

            @Override
            public String toString() {
                return String.format("Query: param=%s",config.getParam());
            }
        };
    }

    @Validated
    public static class Config {

        @NotEmpty
        private String param;

        public String getParam() {
            return param;
        }

        public QueryParamRoutePredicateFactory.Config setParam(String param) {
            this.param = param;
            return this;
        }
    }
}