Spring Cloud Gateway配置路由的方式主要有两种方式，其一是在yml文件中配置，其二是通过硬编码创建RouteLocator实例，但是这两种方式都不支持动态配置，我们的需求是通过Nacos配置中心变更路由规则，Gateway能够实时刷新然后立即生效，基于这种需求，我的思路是通过注册Nacos配置服务的监听器，待收到服务端配置变更的事件后主动刷新Gateway的路由缓存。
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通过源码Gateway自动配置类GatewayAutoConfiguration发现(如上图)，RouteDefinitionRepository的实现类是用来存储路由信息的，唯一的实现类是InMemoryRouteDefinitionRepository，根据条件判断注解，在实例化过程中首先查找Spring上下文有没有自定义的RouteDefinitionRepository实现类，如果没有默认用InMemoryRouteDefinitionRepository，所以做动态路由只要实现RouteDefinitionRepository接口即可，具体实现如下：
引入nacos客户端pom依赖：
<!-- https://mvnrepository.com/artifact/com.alibaba.nacos/nacos-api -->
<dependency>
<groupId>com.alibaba.nacos</groupId>
<artifactId>nacos-client</artifactId>
<version>1.1.4</version>
</dependency>
Nacos服务的配置类，主要为了实例化ConfigService：
@Component
@ConfigurationProperties(prefix = "nacos")
@Data
public class NacosConfig {
/* 服务地址 */
private String serverAddr;
/* 命名空间 */
private String namespace;
/**
* encode for nacos config content.
*/
private String encode = "UTF-8";
/**
* nacos maximum number of tolerable server reconnection errors.
*/
private String maxRetry = "3";
/**
* nacos get config long poll timeout.
*/
private String configLongPollTimeout;
/**
* nacos get config failure retry time.
*/
private String configRetryTime;
/**
* If you want to pull it yourself when the program starts to get the configuration
* for the first time, and the registered Listener is used for future configuration
* updates, you can keep the original code unchanged, just add the system parameter:
* enableRemoteSyncConfig = "true" ( But there is network overhead); therefore we
* recommend that you use {@link ConfigService#getConfigAndSignListener} directly.
*/
private boolean enableRemoteSyncConfig = false;
/**
* endpoint for Nacos, the domain name of a service, through which the server address
* can be dynamically obtained.
*/
private String endpoint;
/**
* access key for namespace.
*/
private String accessKey;
/**
* secret key for namespace.
*/
private String secretKey;
/**
* context path for nacos config server.
*/
private String contextPath;
/**
* nacos config cluster name.
*/
private String clusterName;
/**
* 组装配置参数
* @return
*/
public Properties assembleConfigServiceProperties() {
Properties properties = new Properties();
properties.put(SERVER_ADDR, Objects.toString(this.serverAddr, ""));
properties.put(ENCODE, Objects.toString(this.encode, ""));
properties.put(NAMESPACE, Objects.toString(this.namespace, ""));
properties.put(ACCESS_KEY, Objects.toString(this.accessKey, ""));
properties.put(SECRET_KEY, Objects.toString(this.secretKey, ""));
properties.put(CONTEXT_PATH, Objects.toString(this.contextPath, ""));
properties.put(CLUSTER_NAME, Objects.toString(this.clusterName, ""));
properties.put(MAX_RETRY, Objects.toString(this.maxRetry, ""));
properties.put(CONFIG_LONG_POLL_TIMEOUT,
Objects.toString(this.configLongPollTimeout, ""));
properties.put(CONFIG_RETRY_TIME, Objects.toString(this.configRetryTime, ""));
properties.put(ENABLE_REMOTE_SYNC_CONFIG,
Objects.toString(this.enableRemoteSyncConfig, ""));
String endpoint = Objects.toString(this.endpoint, "");
if (endpoint.contains(":")) {
int index = endpoint.indexOf(":");
properties.put(ENDPOINT, endpoint.substring(0, index));
properties.put(ENDPOINT_PORT, endpoint.substring(index + 1));
} else {
properties.put(ENDPOINT, endpoint);
}
return properties;
}
/**
* 实例化Nacos配置服务
* @return
*/
@Bean
public ConfigService configService() throws NacosException {
return NacosFactory.createConfigService(this.assembleConfigServiceProperties());
}
/**
* 实例化Nacos路由定义存储器
* @return
*/
@Bean
public NacosRouteDefinitionRepository nacosRouteDefinitionRepository(ApplicationEventPublisher publisher,
ConfigService configService) {
return new NacosRouteDefinitionRepository(publisher, configService);
}
}
自定义Nacos路由存储器：
/**
* Nacos路由定义存储器
*/
@Slf4j
public class NacosRouteDefinitionRepository implements RouteDefinitionRepository {
/* nacos配置属性 */
private static final String NACOS_DATA_ID = "gateway";
private static final String NACOS_GROUP = "DEFAULT_GROUP";
private final Map<String, RouteDefinition> routes = Maps.newHashMap();
private ApplicationEventPublisher publisher;
private ConfigService configService;
public NacosRouteDefinitionRepository(ApplicationEventPublisher publisher,
ConfigService configService) {
this.publisher = publisher;
this.configService = configService;
initRouteDefinitions();
registerNacosListener();
}
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
return Flux.fromIterable(routes.values());
}
@Override
public Mono<Void> save(Mono<RouteDefinition> route) {
return null;
}
@Override
public Mono<Void> delete(Mono<String> routeId) {
return null;
}
/**
* 初始化路由
*/
private void initRouteDefinitions() {
this.loadRouteDefinitions();
}
/**
* 注册Nacos监听
*/
private void registerNacosListener() {
try {
this.configService.addListener(NACOS_DATA_ID, NACOS_GROUP, new NacosListener());
} catch (NacosException e) {
log.error("register nacos listener error:{}", ExceptionUtils.getStackTrace(e));
}
}
/**
* 加载路由
*/
private void loadRouteDefinitions() {
try {
String content = configService.getConfig(NACOS_DATA_ID, NACOS_GROUP,5000);
List<RouteDefinition> routeDefinitions = convert(content);
routeDefinitions.forEach(routeDefinition -> {
routes.put(routeDefinition.getId(), routeDefinition);
});
} catch (Exception e) {
if (e instanceof NacosException) {
log.error("loadRouteDefinitions from nacos error:{}", ExceptionUtils.getStackTrace(e));
} else {
log.error("loadRouteDefinitions error:{}", ExceptionUtils.getStackTrace(e));
}
}
}
/**
* 转换路由
* @param content 路由内容
* @return
*/
private List<RouteDefinition> convert(String content) throws IOException {
if (StringUtils.isNotBlank(content)) {
String result = PropertiesUtil.getKey(content, "gateway.routes");
if (StringUtils.isNotBlank(result) ) {
return JSONObject.parseArray(result, RouteDefinition.class);
}
}
return Lists.newArrayList();
}
/* Nacos配置事件监听 */
private class NacosListener implements Listener {
@Override
public Executor getExecutor() {
return null;
}
@Override
public void receiveConfigInfo(String configInfo) {
synchronized (NacosListener.class) {
loadRouteDefinitions();
}
// 发布刷新路由事件
publisher.publishEvent(new RefreshRoutesEvent(this));
}
}
}
自定义路由存储器，注册自定义的Nacos监听器，实现receiveConfigInfo方法，当收到Nacos服务端配置变更事件后，会调用receiveConfigInfo方法，然后去加载最新的路由配置信息并存入Map中(参考了InMemoryRouteDefinitionRepository实现，将路由信息用Map存储，通过路由ID去重)，最后发布刷新路由事件(RefreshRoutesEvent)，缓存路由定位器CachingRouteLocator会监听该事件，并重新拉取最新的路由配置信息，实时生效。
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