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詳解SpringCloud eureka服務(wù)狀態(tài)監(jiān)聽

更新時(shí)間：2018年07月19日 10:06:58 作者：時(shí)光沉舊了少年

這篇文章主要介紹了詳解SpringCloud eureka服務(wù)狀態(tài)監(jiān)聽，小編覺得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過來看看吧

一.前言

近期由于公司不同平臺(tái)項(xiàng)目之間的業(yè)務(wù)整合,需要做到相互訪問! 每個(gè)平臺(tái)均有自己的注冊(cè)中心和服務(wù),且注冊(cè)中心相互之間并沒有相互注冊(cè)!

借助spring的事件監(jiān)聽,在eureka-server端監(jiān)聽服務(wù)注冊(cè),將所有服務(wù)的ip和port存放至redis庫(kù),然后讓其他平臺(tái)服務(wù)通過redis庫(kù)獲取ip和端口號(hào),進(jìn)而進(jìn)行http調(diào)用.結(jié)構(gòu)圖如下:

二.事件解析

事件列表

在org.springframework.cloud.netflix.eureka.server.event包下會(huì)發(fā)現(xiàn)如下類:

EurekaInstanceCanceledEvent: 服務(wù)下線事件
EurekaInstanceRegisteredEvent: 服務(wù)注冊(cè)事件
EurekaInstanceRenewedEvent: 服務(wù)續(xù)約事件
EurekaRegistryAvailableEvent: eureka注冊(cè)中心啟動(dòng)事件
EurekaServerStartedEvent: eureka server啟動(dòng)時(shí)間

源碼分析

打開org.springframework.cloud.netflix.eureka.server.InstanceRegistry類,會(huì)發(fā)現(xiàn)當(dāng)eureka服務(wù)續(xù)約、注冊(cè)、取消等時(shí),spring會(huì)publish不同的事件,對(duì)應(yīng)的事件類就是上面的列表.

續(xù)約事件

 @Override
 public boolean renew(final String appName, final String serverId,
   boolean isReplication) {
  log("renew " + appName + " serverId " + serverId + ", isReplication {}"
    + isReplication);
  List<Application> applications = getSortedApplications();
  for (Application input : applications) {
   if (input.getName().equals(appName)) {
    InstanceInfo instance = null;
    for (InstanceInfo info : input.getInstances()) {
     if (info.getId().equals(serverId)) {
      instance = info;
      break;
     }
    }
    // 發(fā)布續(xù)約事件
    publishEvent(new EurekaInstanceRenewedEvent(this, appName, serverId,
      instance, isReplication));
    break;
   }
  }
  return super.renew(appName, serverId, isReplication);
 }

注冊(cè)事件

 @Override
 public void register(InstanceInfo info, int leaseDuration, boolean isReplication) {
  handleRegistration(info, leaseDuration, isReplication);
  super.register(info, leaseDuration, isReplication);
 }
 
  private void handleRegistration(InstanceInfo info, int leaseDuration,
   boolean isReplication) {
  log("register " + info.getAppName() + ", vip " + info.getVIPAddress()
    + ", leaseDuration " + leaseDuration + ", isReplication "
    + isReplication);
  // 發(fā)布注冊(cè)事件
  publishEvent(new EurekaInstanceRegisteredEvent(this, info, leaseDuration,
    isReplication));
 }

事件監(jiān)聽

通過上面的源碼追溯,我們已經(jīng)得到對(duì)應(yīng)的事件類了,所以現(xiàn)在要做的僅僅是監(jiān)聽對(duì)應(yīng)的事件即可,至此已經(jīng)完成了我們所需要對(duì)事件監(jiān)聽后的業(yè)務(wù)處理!

@Component
public class EurekaStateChangeListener {

 @Value("${iptable.platform}")
 private String platform;
 
 @Autowired
 private RedisTemplate<String, String> redisTemplate;

 private static Logger logger = LoggerFactory.getLogger(EurekaStateChangeListener.class);
 private static final String COLON = ":";

 @EventListener//(condition = "#event.replication==false")
 public void listen(EurekaInstanceCanceledEvent eurekaInstanceCanceledEvent) {
  // 服務(wù)斷線事件
  String appName = eurekaInstanceCanceledEvent.getAppName();
  String serverId = eurekaInstanceCanceledEvent.getServerId();
  Objects.requireNonNull(appName, "服務(wù)名不能為空!");

  SetOperations<String, String> opsForSet = redisTemplate.opsForSet();
  opsForSet.remove((platform + appName).toLowerCase(), serverId);
  logger.info(">>>>>>> 失效服務(wù):{},已被剔除!", serverId);
 }

 @EventListener//(condition = "#event.replication==false")
 public void listen(EurekaInstanceRegisteredEvent event) {
  // 服務(wù)注冊(cè)
  InstanceInfo instanceInfo = event.getInstanceInfo();
  String appName = instanceInfo.getAppName();
  Objects.requireNonNull(appName, "服務(wù)名不能為空!");

  SetOperations<String, String> opsForSet = redisTemplate.opsForSet();
  opsForSet.add((platform + appName).toLowerCase(), instanceInfo.getIPAddr() + COLON + instanceInfo.getPort());
  logger.info(">>>>>>> 服務(wù)名:{},端口號(hào):{},已緩存至redis", appName, instanceInfo.getPort());
 }

 @EventListener//(condition = "#event.replication==false")
 public void listen(EurekaInstanceRenewedEvent event) {
  // 服務(wù)續(xù)約
  logger.info(">>>>>>>>>>>>>>>Server續(xù)約:" + event.getServerId());
 }

 @EventListener
 public void listen(EurekaRegistryAvailableEvent event) {
  // 注冊(cè)中心啟動(dòng)
  logger.info(">>>>>>>>>>>>>>>Server注冊(cè)中心:" + event);
 }

 @EventListener
 public void listen(EurekaServerStartedEvent event) {
  // Server啟動(dòng)
  logger.info(">>>>>>>>>>>>>>>Server啟動(dòng):" + event);
 }
}

注意事項(xiàng)

[ ] 版本問題:

當(dāng)時(shí)項(xiàng)目組用的SpringCloud版本是Brixton.RELEASE,該版本有一個(gè)問題就是服務(wù)注冊(cè)和下線并不會(huì)出發(fā)對(duì)應(yīng)的事件,所以導(dǎo)致一直監(jiān)聽不到.解決的辦法也很簡(jiǎn)單,只要升級(jí)版本即可,我已經(jīng)升級(jí)到最新版本Finchley.RELEASE.

傳送門,點(diǎn)我

[ ] 重復(fù)監(jiān)聽:

例如,在續(xù)約的時(shí)候,eureka會(huì)發(fā)出2條EurekaInstanceRenewedEvent事件,但是2條事件的屬性卻不一樣!一個(gè)事件的屬性replication為true,另外一個(gè)為false.如果我們只想處理replication=true的事件,如下配置即可:

 @EventListener(condition = "#event.replication==false")
 public void listen(EurekaInstanceRenewedEvent event) {
  // 服務(wù)續(xù)約
  logger.info(">>>>>>>>>>>>>>>Server續(xù)約:" + event.getServerId());
 }

GitHub代碼,點(diǎn)我

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