本篇内容主要讲解“nacos client中ServerListManager的start有什么作用”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“nacos client中ServerListManager的start有什么作用”吧!
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本文主要研究一下nacos client的ServerListManager的start
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/config/impl/ServerListManager.java
public class ServerListManager {
private static final Logger LOGGER = LogUtils.logger(ServerListManager.class);
private static final String HTTPS = "https://";
private static final String HTTP = "http://";
//......
public synchronized void start() throws NacosException {
if (isStarted || isFixed) {
return;
}
GetServerListTask getServersTask = new GetServerListTask(addressServerUrl);
for (int i = 0; i < initServerlistRetryTimes && serverUrls.isEmpty(); ++i) {
getServersTask.run();
try {
this.wait((i + 1) * 100L);
} catch (Exception e) {
LOGGER.warn("get serverlist fail,url: {}", addressServerUrl);
}
}
if (serverUrls.isEmpty()) {
LOGGER.error("[init-serverlist] fail to get NACOS-server serverlist! env: {}, url: {}", name,
addressServerUrl);
throw new NacosException(NacosException.SERVER_ERROR,
"fail to get NACOS-server serverlist! env:" + name + ", not connnect url:" + addressServerUrl);
}
TimerService.scheduleWithFixedDelay(getServersTask, 0L, 30L, TimeUnit.SECONDS);
isStarted = true;
}
//......
}ServerListManager的start方法在非isStarted且非isFixed的条件下会执行GetServerListTask，失败重试次数为initServerlistRetryTimes，如果serverUrls为空则抛出NacosException；如果不为空则注册该getServersTask每隔30秒执行一次来刷新server list
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/config/impl/ServerListManager.java
public class ServerListManager {
//......
class GetServerListTask implements Runnable {
final String url;
GetServerListTask(String url) {
this.url = url;
}
@Override
public void run() {
/**
* get serverlist from nameserver
*/
try {
updateIfChanged(getApacheServerList(url, name));
} catch (Exception e) {
LOGGER.error("[" + name + "][update-serverlist] failed to update serverlist from address server!",
e);
}
}
}
private void updateIfChanged(List newList) {
if (null == newList || newList.isEmpty()) {
LOGGER.warn("[update-serverlist] current serverlist from address server is empty!!!");
return;
}
List newServerAddrList = new ArrayList();
for (String server : newList) {
if (server.startsWith(HTTP) || server.startsWith(HTTPS)) {
newServerAddrList.add(server);
} else {
newServerAddrList.add(HTTP + server);
}
}
/**
* no change
*/
if (newServerAddrList.equals(serverUrls)) {
return;
}
serverUrls = new ArrayList(newServerAddrList);
iterator = iterator();
currentServerAddr = iterator.next();
EventDispatcher.fireEvent(new ServerlistChangeEvent());
LOGGER.info("[{}] [update-serverlist] serverlist updated to {}", name, serverUrls);
}
private List getApacheServerList(String url, String name) {
try {
HttpResult httpResult = HttpSimpleClient.httpGet(url, null, null, null, 3000);
if (HttpURLConnection.HTTP_OK == httpResult.code) {
if (DEFAULT_NAME.equals(name)) {
EnvUtil.setSelfEnv(httpResult.headers);
}
List lines = IOUtils.readLines(new StringReader(httpResult.content));
List result = new ArrayList(lines.size());
for (String serverAddr : lines) {
if (org.apache.commons.lang3.StringUtils.isNotBlank(serverAddr)) {
String[] ipPort = serverAddr.trim().split(":");
String ip = ipPort[0].trim();
if (ipPort.length == 1) {
result.add(ip + ":" + ParamUtil.getDefaultServerPort());
} else {
result.add(serverAddr);
}
}
}
return result;
} else {
LOGGER.error("[check-serverlist] error. addressServerUrl: {}, code: {}", addressServerUrl,
httpResult.code);
return null;
}
} catch (IOException e) {
LOGGER.error("[check-serverlist] exception. url: " + url, e);
return null;
}
}
//......
} GetServerListTask实现了Runnable接口，其run方法会通过getApacheServerList请求addressServerUrl获取服务端地址列表，然后执行updateIfChanged方法；该方法会判断server list是否有变更，有变更则更新serverUrls，然后发布ServerlistChangeEvent
ServerListManager的start方法在非isStarted且非isFixed的条件下会执行GetServerListTask，失败重试次数为initServerlistRetryTimes，如果serverUrls为空则抛出NacosException；如果不为空则注册该getServersTask每隔30秒执行一次来刷新server list
到此，相信大家对“nacos client中ServerListManager的start有什么作用”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
