SpringCloudGateway手动编写路由规则对请求进行转发

这篇文章主要是提供一种转发路由的代码实现方式，之前说的gateway都是使用配置文件来对请求进行路由，这样虽然很简单，但是不够灵活，如果后端对应很多服务实例，网关想要根据自己的规则来转发请求，比如编写不同的负载均衡策略，做一些特别的权重，以及在运行过程中动态的变更转发地址，这些用配置文件来做都不够灵活，没法自由的定义规则。

涉及的gateway版本 

<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-gateway</artifactId> <version>2.1.4.RELEASE</version> </dependency>

主要实现过程还是实现GatewayFilter接口，获取到要指定的IP地址与端口，然后组装成URI与Route，最后转发出去 

import cn.hutool.core.util.ObjectUtil; import cn.hutool.core.util.StrUtil; import com.ecwid.consul.v1.health.model.HealthService; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.cloud.gateway.filter.GatewayFilter; import org.springframework.cloud.gateway.filter.GatewayFilterChain; import org.springframework.cloud.gateway.route.Route; import org.springframework.core.Ordered; import org.springframework.http.server.reactive.ServerHttpResponse; import org.springframework.web.server.ServerWebExchange; import org.springframework.web.util.UriComponentsBuilder; import java.net.URI; import java.util.List; import java.util.Optional; import reactor.core.publisher.Mono; import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR; /**
 * 转发路由，通过负载均衡对后端服务进行访问
 *
 */ @Slf4j public class RouteFilter implements GatewayFilter, Ordered {

    @Autowired private RedisUtil redisUtil;

    @Autowired private LoadBalanceHandler loadBalance;

    @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { ServerHttpResponse response = exchange.getResponse(); //获取原来的请求路径 String requestPath = exchange.getAttribute(FilterDict.SYSTEM_REQUEST_PATH); //randomSelectInstance方***获取到一个"ip:port"这样结构的字符串 String instanceInfo = loadBalance.randomSelectInstance(); //如果没有服务，则直接返回报错 if (StrUtil.isEmpty(instanceInfo)) { return response.writeWith(Mono.just(GateWayFilterUtils.writeData(exchange, RecoError.GEN_SERVER_BUSY)));
        } //用于测试负载均衡算法对IP分配是否均衡 //        redisUtil.zIncrementScore("test:gateway:load:ip",instanceInfo,1); //分割地址中IP和端口 String[] serviceAddress = instanceInfo.split(StrUtil.COLON); String requestSchema = exchange.getRequest().getURI().getScheme(); //拼接URL的数据 assert ObjectUtil.isNotNull(requestPath); URI uri = UriComponentsBuilder.
                newInstance().scheme(requestSchema).
                host(serviceAddress[0].trim()).port(Integer.parseInt(serviceAddress[1].trim()))
                .path(requestPath).query(exchange.getRequest().getURI().getRawQuery()).build(true)
                .toUri(); //将拼接好的URL装入新的exchange ServerWebExchange mutateExchange = exchange.mutate().request(builder -> builder.uri(uri).build()).build(); Optional<Route> route = Optional.of(exchange.getAttribute(GATEWAY_ROUTE_ATTR)); Route newRoute = Route.async()
                .asyncPredicate(route.get().getPredicate())
                .filters(route.get().getFilters())
                .id(route.get().getId())
                .order(route.get().getOrder())
                .uri(uri).build();
        mutateExchange.getAttributes().put(GATEWAY_ROUTE_ATTR, newRoute);
        mutateExchange.getAttributes().put(FilterDict.SYSTEM_APP_IP_ADDR, serviceAddress[0]); return chain.filter(mutateExchange);
    }

    @Override public int getOrder() { return FilterDict.SYSTEM_FILTER_ORDER + 4;
    }
}

单独编写路由filter以后，还需要引入才能执行，在全局配置中倒入bean，最后启动就可以执行了 

import org.springframework.beans.factory.annotation.Value; import org.springframework.cloud.gateway.filter.ratelimit.RedisRateLimiter; import org.springframework.cloud.gateway.route.RouteLocator; import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import lombok.extern.slf4j.Slf4j; import java.time.Duration; /**
 * 全局过滤器配置加载
 *
 * @author :wcy
 */ @Slf4j @Configuration public class GlobalFilterConfigure { //用于设置路由的 @Bean public RouteFilter routeFilter(){ return new RouteFilter();
    } /**
     * 将所有自定义的filter加载进来
     */ @Bean public RouteLocator customerRouteLocator(RouteLocatorBuilder builder, RedisRateLimiter redisRateLimiter) { return builder.routes()
                .route(r -> r.path(FilterDict.GATEWAY_BASE_INTERCEPT_URL) //将自定义的filter加载进来 .filters(f -> f.filters(routeFilter()) //请求大小 .setRequestSize(requestLimitSize) //请求限流,目前使用请求IP,以后可以扩展使用其他限定组合 //                                .filter(rateLimitByIpGatewayFilter()) )
                        .uri("http://127.0.0.1:" + servicePort + "/actuator/health")
                        .order(FilterDict.SYSTEM_FILTER_ORDER)
                        .id(FilterDict.GATEWAY_ROUTE_NAME)
                ).build();
    }

}