Spring Cloud Zuul的动态路由怎样做？集成Nacos实现很简单

一、说明

网关的核心概念就是路由配置和路由规则，而作为所有请求流量的入口，在实际生产环境中为了保证高可靠和高可用，是尽量要避免重启的，所以实现动态路由是非常有必要的；本文主要介绍实现的思路，并且以Nacos为数据源来讲解

二、实现要点

要实现动态路由只需关注下面4个点

网关启动时，动态路由的数据怎样加载进来
静态路由与动态路由以那个为准，ps：静态路由指的是配置文件里写死的路由配置
监听动态路由的数据源变化
数据有变化时怎样通知zuul刷新路由

三、具体实现

3.1. 实现动态路由的数据加载

重写SimpleRouteLocator类的locateRoutes方法，此方法是加载路由配置的，父类中是获取properties中的路由配置，可以通过扩展此方法，达到动态获取配置的目的
这里采用静态路由与动态路由共存，相同路由id以动态路由优先覆盖的实现方式

AbstractDynRouteLocator类可查看：AbstractDynRouteLocator.java

public abstract class AbstractDynRouteLocator extends SimpleRouteLocator implements RefreshableRouteLocator {
    private ZuulProperties properties;

    public AbstractDynRouteLocator(String servletPath, ZuulProperties properties) {
        super(servletPath, properties);
        this.properties = properties;
    }

    /**
     * 刷新路由
     */
    @Override
    public void refresh() {
        doRefresh();
    }

    @Override
    protected Map<String, ZuulRoute> locateRoutes() {
        LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<>();
        // 从application.properties中加载静态路由信息
        routesMap.putAll(super.locateRoutes());
        // 从数据源中加载动态路由信息
        routesMap.putAll(loadDynamicRoute());
        // 优化一下配置
        LinkedHashMap<String, ZuulRoute> values = new LinkedHashMap<>();
        for (Map.Entry<String, ZuulRoute> entry : routesMap.entrySet()) {
            String path = entry.getKey();
            // Prepend with slash if not already present.
            if (!path.startsWith("/")) {
                path = "/" + path;
            }
            if (StringUtils.hasText(this.properties.getPrefix())) {
                path = this.properties.getPrefix() + path;
                if (!path.startsWith("/")) {
                    path = "/" + path;
                }
            }
            values.put(path, entry.getValue());
        }
        return values;
    }

    /**
     * 加载路由配置，由子类去实现
     */
    public abstract Map<String, ZuulRoute> loadDynamicRoute();
}

由于动态路由的数据可以有很多种途径，如：Nacos、Redis、Zookeeper、DB等，所以这里定义一个抽象类，由具体的实现类去定义loadDynamicRoute方法

3.2. Nacos路由实现类

NacosDynRouteLocator类完整的代码实现可查看：NacosDynRouteLocator.java

3.2.1. 实现`loadDynamicRoute`方法获取动态数据

    @Override
    public Map<String, ZuulProperties.ZuulRoute> loadDynamicRoute() {
        Map<String, ZuulRoute> routes = new LinkedHashMap<>();
        if (zuulRouteEntities == null) {
            zuulRouteEntities = getNacosConfig();
        }
        for (ZuulRouteEntity result : zuulRouteEntities) {
            if (StrUtil.isBlank(result.getPath()) || !result.isEnabled()) {
                continue;
            }
            ZuulRoute zuulRoute = new ZuulRoute();
            BeanUtil.copyProperties(result, zuulRoute);
            routes.put(zuulRoute.getPath(), zuulRoute);
        }
        return routes;
    }
        
    private List<ZuulRouteEntity> getNacosConfig() {
        try {
            String content = nacosConfigProperties.configServiceInstance().getConfig(ZUUL_DATA_ID, ZUUL_GROUP_ID,5000);
            return getListByStr(content);
        } catch (NacosException e) {
            log.error("listenerNacos-error", e);
        }
        return new ArrayList<>(0);
    }

3.2.2. 增加`NacosListener`监听路由数据变化

    private void addListener() {
        try {
            nacosConfigProperties.configServiceInstance().addListener(ZUUL_DATA_ID, ZUUL_GROUP_ID, new Listener() {
                @Override
                public Executor getExecutor() {
                    return null;
                }

                @Override
                public void receiveConfigInfo(String configInfo) {
                    //赋值路由信息
                    locator.setZuulRouteEntities(getListByStr(configInfo));
                    RoutesRefreshedEvent routesRefreshedEvent = new RoutesRefreshedEvent(locator);
                    publisher.publishEvent(routesRefreshedEvent);
                }
            });
        } catch (NacosException e) {
            log.error("nacos-addListener-error", e);
        }
    }

注意路由数据变化后不需要自己手动刷新路由，只需要给zuul发送一个RoutesRefreshedEvent事件即可，zuul自己有个ZuulRefreshListener类会监听事件帮我们刷新路由

3.3. 配置类创建`NacosDynRouteLocator`的Bean

DynamicZuulRouteConfig可查看：NacosDynRouteLocator.java

@Configuration
@ConditionalOnProperty(prefix = "zlt.gateway.dynamicRoute", name = "enabled", havingValue = "true")
public class DynamicZuulRouteConfig {
    @Autowired
    private ZuulProperties zuulProperties;

    @Autowired
    private DispatcherServletPath dispatcherServletPath;

    /**
     * Nacos实现方式
     */
    @Configuration
    @ConditionalOnProperty(prefix = "zlt.gateway.dynamicRoute", name = "dataType", havingValue = "nacos", matchIfMissing = true)
    public class NacosZuulRoute {
        @Autowired
        private NacosConfigProperties nacosConfigProperties;

        @Autowired
        private ApplicationEventPublisher publisher;

        @Bean
        public NacosDynRouteLocator nacosDynRouteLocator() {
            return new NacosDynRouteLocator(nacosConfigProperties, publisher, dispatcherServletPath.getPrefix(), zuulProperties);
        }
    }
}

这里通过自定义配置来控制是否开启动态路由功能

3.4. 添加`Nacos`路由配置

file
新增配置项：

Data Id：zuul-routes
Group：ZUUL_GATEWAY
配置内容：

[
    {
        "enabled":true,
        "id":"csdn",
        "path":"/csdn/**",
        "retryable":false,
        "stripPrefix":true,
        "url":"https://www.csdn.net/"
    }, {
        "enabled":true,
        "id":"github",
        "path":"/github/**",
        "retryable":false,
        "stripPrefix":true,
        "url":"http://github.com/"
    }
]