@Data
@ConfigurationProperties(prefix = "hm.cart")
public class CartProperties {
    private int timeout;
}

package com.hmall.cart.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Data
@Component
@ConfigurationProperties(prefix = "hm.cart")
public class CartProperties {
    private Integer maxItems;
}

@Service
@RequiredArgsConstructor
public class CartServiceImpl extends ServiceImpl<CartMapper, Cart> implements ICartService {
    private final CartProperties cartProperties;

    @Override
    public Cart getCart() {
        System.out.println("购物车最大数量" + cartProperties.getMaxItems());
    }
}

package com.hmall.gateway.router;

import cn.hutool.json.JSONUtil;
import com.alibaba.cloud.nacos.NacosConfigManager;
import com.alibaba.nacos.api.config.listener.Listener;
import com.alibaba.nacos.api.exception.NacosException;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

import javax.annotation.PostConstruct;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Executor;

@Component
@Slf4j
@RequiredArgsConstructor
public class DynamicRouteLoader {
    //注入`Nacos`的配置管理器
    private final NacosConfigManager nacosConfigManager;
    private final RouteDefinitionWriter routeDefinitionWriter;
    private final String dataId = "gateway-router.json";
    private final String groupName = "DEFAULT_GROUP";
    private Set<String> routeIds = new HashSet<>();

    //初始化动态路由监听器
    //@PostConstruct注解主要用于标记在依赖注入完成后需要执行的初始化方法。
    //加入此注解后该方法会在类加载完毕时立即执行
    @PostConstruct
    public void initRouteListener() throws NacosException {
        //项目启动时先读取配置 并加入监听器随时监听变动
        String configAndSignListener = nacosConfigManager.getConfigService().getConfigAndSignListener(dataId, groupName, 5000, new Listener() {
            @Override
            public Executor getExecutor() {
                //线程池
                //返回线程池后改监听可在特定线程异步执行
                return null;
            }

            @Override
            public void receiveConfigInfo(String configInfo) {
                //拿到配置后更新路由表
                updateRouteInfo(configInfo);
            }
        });
        //第一次读取到的配置也需要更新到路由表
        updateRouteInfo(configAndSignListener);
    }

    //更新路由表
    public void updateRouteInfo(String configInfo) {
        log.info("监听到更新路由表：{}", configInfo);
        //将配置的json文件转为RouteDefinition类型
        List<RouteDefinition> list = JSONUtil.toList(configInfo, RouteDefinition.class);
        //删除旧的路由信息
        for (String routeId : routeIds) {
            routeDefinitionWriter.delete(Mono.just(routeId)).subscribe();
        }
        //清空旧的集合
        routeIds.clear();
        //遍历每一个路由逐个更新
        for (RouteDefinition routeDefinition : list) {
            //更新路由表
            //subscribe(): 订阅，将数据发送给订阅者
            routeDefinitionWriter.save(Mono.just(routeDefinition)).subscribe();
            //将已经更新的路由id保存在set集合中
            routeIds.add(routeDefinition.getId());
        }
    }
}