详解SpringCloud-gateway动态路由两种方式，以及路由加载过程

太过爱你忘了你带给我的痛 2022-05-14 14:35 436阅读 0赞

gateway配置路由主要有两种方式，一种是用yml配置文件，一种是写代码里，这两种方式都是不支持动态配置的。如：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 1][]

下面就来看看gateway是如何加载这些配置信息的。

### 1 路由初始化 ###

无论是yml还是代码，这些配置最终都是被封装到RouteDefinition对象中。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 2][]

一个RouteDefinition有个唯一的ID，如果不指定，就默认是UUID，多个RouteDefinition组成了gateway的路由系统。

所有路由信息在系统启动时就被加载装配好了，并存到了内存里。我们从源码来看看。![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 3][]

圆圈里就是装配yml文件的，它返回的是PropertiesRouteDefinitionLocator，该类继承了RouteDefinitionLocator，RouteDefinitionLocator就是路由的装载器，里面只有一个方法，就是获取路由信息的。该接口有多个实现类，分别对应不同方式配置的路由方式。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 5][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 6][]

通过这几个实现类，再结合上面的AutoConfiguration里面的Primary信息，就知道加载配置信息的顺序。

参考：[https://www.jianshu.com/p/b02c7495eb5e][https_www.jianshu.com_p_b02c7495eb5e]

[https://blog.csdn.net/X5fnncxzq4/article/details/80221488][https_blog.csdn.net_X5fnncxzq4_article_details_80221488]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 7][]

这是第一顺序，就是从CachingRouteLocator中获取路由信息，我们可以打开该类进行验证。![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 8][]

不管发起什么请求，必然会走上面的断点处。请求一次，走一次。这是将路由信息缓存到了Map中。配置信息一旦请求过一次，就会被缓存到上图的CachingRouteLocator类中，再次发起请求后，会直接从map中读取。

如果想动态刷新配置信息，就需要发起一个RefreshRoutesEvent的事件，上图的cache会监听该事件，并重新拉取路由配置信息。

通过下图，可以看到如果没有RouteDefinitionRepository的实例，则默认用InMemoryRouteDefinitionRepository。而做动态路由的关键就在这里。即通过自定义的RouteDefinitionRepository类，来提供路由配置信息。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 9][]

例如：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 10][]

在getRouteDefinitions方法返回你自定义的路由配置信息即可。这里可以用数据库、nosql等等任意你喜欢的方式来提供。而且配置信息修改后，发起一次RefreshRoutesEvent事件即可让配置生效。这就是动态配置路由的核心所在，下面来看具体代码实现。

### 2 基于数据库、缓存的动态路由 ###

pom.xml如下

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.maimeng</groupId>
        <artifactId>apigateway</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>apigateway</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.6.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
            <spring-cloud.version>Finchley.SR1</spring-cloud.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-gateway</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-webflux</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-redis</artifactId>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.51</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    
    </project>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 11][]

注意这里是SR1，经测试SR2有bug，会出问题。

@Configuration
    public class RedisConfig {
    
        @Bean(name = {"redisTemplate", "stringRedisTemplate"})
        public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory factory) {
            StringRedisTemplate redisTemplate = new StringRedisTemplate();
            redisTemplate.setConnectionFactory(factory);
            return redisTemplate;
        }
    
    }

核心类：

@Component
    public class RedisRouteDefinitionRepository implements RouteDefinitionRepository {
    
        public static final String GATEWAY_ROUTES = "geteway_routes";
    
        @Resource
        private StringRedisTemplate redisTemplate;
    
        @Override
        public Flux<RouteDefinition> getRouteDefinitions() {
            List<RouteDefinition> routeDefinitions = new ArrayList<>();
            redisTemplate.opsForHash().values(GATEWAY_ROUTES).stream()
                    .forEach(routeDefinition -> routeDefinitions.add(JSON.parseObject(routeDefinition.toString(), RouteDefinition.class)));
            return Flux.fromIterable(routeDefinitions);
        }
    
        @Override
        public Mono<Void> save(Mono<RouteDefinition> route) {
            return null;
        }
    
        @Override
        public Mono<Void> delete(Mono<String> routeId) {
            return null;
        }
    
    }

主要是在get方法里，此处从redis里获取配置好的Definition。

然后我们的工作就是将配置信息，放到redis里即可。

下面就是我模拟的一个配置，等同于在yml里

spring:
      cloud:
        gateway:
          routes:
          - id: header
            uri: http://localhost:8888/header
            filters:
            - AddRequestHeader=header, addHeader
            - AddRequestParameter=param, addParam
            predicates:
            - Path=/jd

@Resource
        private StringRedisTemplate redisTemplate;
        @PostConstruct
        public void main() {
            RouteDefinition definition = new RouteDefinition();
            definition.setId("id");
            URI uri = UriComponentsBuilder.fromHttpUrl("http://127.0.0.1:8888/header").build().toUri();
           // URI uri = UriComponentsBuilder.fromHttpUrl("http://baidu.com").build().toUri();
            definition.setUri(uri);
    
            //定义第一个断言
            PredicateDefinition predicate = new PredicateDefinition();
            predicate.setName("Path");
    
            Map<String, String> predicateParams = new HashMap<>(8);
            predicateParams.put("pattern", "/jd");
            predicate.setArgs(predicateParams);
    
            //定义Filter
            FilterDefinition filter = new FilterDefinition();
            filter.setName("AddRequestHeader");
            Map<String, String> filterParams = new HashMap<>(8);
            //该_genkey_前缀是固定的，见org.springframework.cloud.gateway.support.NameUtils类
            filterParams.put("_genkey_0", "header");
            filterParams.put("_genkey_1", "addHeader");
            filter.setArgs(filterParams);
    
            FilterDefinition filter1 = new FilterDefinition();
            filter1.setName("AddRequestParameter");
            Map<String, String> filter1Params = new HashMap<>(8);
            filter1Params.put("_genkey_0", "param");
            filter1Params.put("_genkey_1", "addParam");
            filter1.setArgs(filter1Params);
    
            definition.setFilters(Arrays.asList(filter, filter1));
            definition.setPredicates(Arrays.asList(predicate));
    
            System.out.println("definition:" + JSON.toJSONString(definition));
            redisTemplate.opsForHash().put(GATEWAY_ROUTES, "key", JSON.toJSONString(definition));
        }

定义好后，将其放到redis里，之后启动项目访问/jd，再启动后台的localhost:8888项目。即可进行验证。

之后如果要动态修改配置，就可以通过类似于上面的方式，来获取json字符串，然后将字符串放到redis里进行替换。替换后，需要通知gateway主动刷新一下。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 12][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW55YWxlaXhpYW93dQ_size_27_color_FFFFFF_t_70 13][]

刷新时，可以定义一个controller，然后调用一下notifyChanged()方法，就能完成新配置的替换了。

### 3 通过REST接口 ###

gateway是自带接口能增删改查配置的，这个网上有比较多的教程，随便找个看看就明白了。譬如：

[http://springcloud.cn/view/368][http_springcloud.cn_view_368]

我发个类作为参考

package com.maimeng.apigateway.route;
    
    import com.alibaba.fastjson.JSON;
    import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
    import org.springframework.cloud.gateway.filter.FilterDefinition;
    import org.springframework.cloud.gateway.handler.predicate.PredicateDefinition;
    import org.springframework.cloud.gateway.route.RouteDefinition;
    import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
    import org.springframework.context.ApplicationEventPublisher;
    import org.springframework.context.ApplicationEventPublisherAware;
    import org.springframework.data.redis.core.StringRedisTemplate;
    import org.springframework.stereotype.Service;
    import org.springframework.web.util.UriComponentsBuilder;
    import reactor.core.publisher.Mono;
    
    import javax.annotation.PostConstruct;
    import javax.annotation.Resource;
    import java.net.URI;
    import java.util.Arrays;
    import java.util.HashMap;
    import java.util.Map;
    
    import static com.maimeng.apigateway.repository.RedisRouteDefinitionRepository.GATEWAY_ROUTES;
    
    /**
     * @author wuweifeng wrote on 2018/10/25.
     */
    @Service
    public class DynamicRouteService implements ApplicationEventPublisherAware {
    
        @Resource
        private RouteDefinitionWriter routeDefinitionWriter;
    
        private ApplicationEventPublisher publisher;
    
        private void notifyChanged() {
            this.publisher.publishEvent(new RefreshRoutesEvent(this));
        }
    
    
        /**
         * 增加路由
         *
         */
        public String add(RouteDefinition definition) {
            routeDefinitionWriter.save(Mono.just(definition)).subscribe();
            notifyChanged();
            return "success";
        }
    
    
        /**
         * 更新路由
         */
        public String update(RouteDefinition definition) {
            try {
                this.routeDefinitionWriter.delete(Mono.just(definition.getId()));
            } catch (Exception e) {
                return "update fail,not find route  routeId: " + definition.getId();
            }
            try {
                routeDefinitionWriter.save(Mono.just(definition)).subscribe();
                notifyChanged();
                return "success";
            } catch (Exception e) {
                return "update route  fail";
            }
    
    
        }
    
        /**
         * 删除路由
         *
         */
        public String delete(String id) {
            try {
                this.routeDefinitionWriter.delete(Mono.just(id)).subscribe();
    
                notifyChanged();
                return "delete success";
            } catch (Exception e) {
                e.printStackTrace();
                return "delete fail";
            }
    
        }
    
        @Override
        public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
            this.publisher = applicationEventPublisher;
        }
    
        @Resource
        private StringRedisTemplate redisTemplate;
        @PostConstruct
        public void main() {
            RouteDefinition definition = new RouteDefinition();
            definition.setId("id");
            URI uri = UriComponentsBuilder.fromHttpUrl("http://127.0.0.1:8888/header").build().toUri();
           // URI uri = UriComponentsBuilder.fromHttpUrl("http://baidu.com").build().toUri();
            definition.setUri(uri);
    
            //定义第一个断言
            PredicateDefinition predicate = new PredicateDefinition();
            predicate.setName("Path");
    
            Map<String, String> predicateParams = new HashMap<>(8);
            predicateParams.put("pattern", "/jd");
            predicate.setArgs(predicateParams);
    
            //定义Filter
            FilterDefinition filter = new FilterDefinition();
            filter.setName("AddRequestHeader");
            Map<String, String> filterParams = new HashMap<>(8);
            //该_genkey_前缀是固定的，见org.springframework.cloud.gateway.support.NameUtils类
            filterParams.put("_genkey_0", "header");
            filterParams.put("_genkey_1", "addHeader");
            filter.setArgs(filterParams);
    
            FilterDefinition filter1 = new FilterDefinition();
            filter1.setName("AddRequestParameter");
            Map<String, String> filter1Params = new HashMap<>(8);
            filter1Params.put("_genkey_0", "param");
            filter1Params.put("_genkey_1", "addParam");
            filter1.setArgs(filter1Params);
    
            definition.setFilters(Arrays.asList(filter, filter1));
            definition.setPredicates(Arrays.asList(predicate));
    
            System.out.println("definition:" + JSON.toJSONString(definition));
            redisTemplate.opsForHash().put(GATEWAY_ROUTES, "key", JSON.toJSONString(definition));
        }
    }

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[https_www.jianshu.com_p_b02c7495eb5e]: https://www.jianshu.com/p/b02c7495eb5e
[https_blog.csdn.net_X5fnncxzq4_article_details_80221488]: https://blog.csdn.net/X5fnncxzq4/article/details/80221488
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[http_springcloud.cn_view_368]: http://springcloud.cn/view/368