Spring Cloud Alibaba实现服务的无损下线功能(案例讲解)

<dependencies>
	<!-- 服务发现 -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
    <!-- nacos 配置 -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
    </dependency>
    <!-- 引入这个是为了使 @NacosConfigListener 注解生效 -->
    <dependency>
        <groupId>com.alibaba.nacos</groupId>
        <artifactId>nacos-spring-context</artifactId>
        <version>1.1.1</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
    <!-- 负载均衡组件 -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-loadbalancer</artifactId>
    </dependency>
    <!-- 使bootstrap.yaml中的配置生效 -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-bootstrap</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

@Component
@Slf4j
public class LosslessOfflineApi {

    @Resource
    private NacosConfigManager nacosConfigManager;
    @Resource
    private NacosServiceManager nacosServiceManager;
    @Resource
    private NacosDiscoveryProperties nacosDiscoveryProperties;

    /**
     * 服务下线
     *
     * @throws NacosException NacosException
     */
    public void offlineService() throws NacosException {
        log.info("触发服务下线 serviceName:[{}]", nacosDiscoveryProperties.getService());
        nacosServiceManager.nacosServiceShutDown();
        nacosConfigManager.getConfigService()
                .publishConfig(NacosConstant.DATA_ID, NacosConstant.GROUP,
                        nacosDiscoveryProperties.getService() + NacosConstant.SPLIT + System.currentTimeMillis());
    }
}

<dependency>
    <groupId>com.alibaba.nacos</groupId>
    <artifactId>nacos-spring-context</artifactId>
    <version>1.1.1</version>
</dependency>

@Configuration
@EnableNacos(globalProperties =
	@NacosProperties(serverAddr = "${spring.cloud.nacos.config.server-addr}")
)
public class NacosConfiguration {
}

@Component
@RequiredArgsConstructor
@Slf4j
public class ListenerConfigChange {
    @Resource
    private DefaultLoadBalancerCacheManager defaultLoadBalancerCacheManager;
    @Resource
    private NacosServiceManager nacosServiceManager;
    @Resource
    private NacosDiscoveryProperties nacosDiscoveryProperties;
    @Resource
    private NacosServiceDiscovery nacosServiceDiscovery;
    @Resource
    private NacosConfigManager nacosConfigManager;

    @NacosConfigListener(groupId = GROUP, dataId = DATA_ID)
    public void configChange(String config) {
        log.warn("==>接收到 无损服务下线 配置变更:[{}]", config);
        String serviceName = config.split(SPLIT)[0];
        log.info("需要无损下线的服务名:[{}]", serviceName);

        Cache cache = defaultLoadBalancerCacheManager.getCache(SERVICE_INSTANCE_CACHE_NAME);
        if (null != cache) {
            cache.evict(serviceName);
            log.info("失效serviceName:[{}]的缓存", serviceName);
        }
    }
}