nacos NamingProxy中getServiceList的原理及用法
本篇内容主要讲解"nacos NamingProxy中getServiceList的原理及用法"，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 NamingProxy中getServiceList的原理及用法"吧!
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本文主要研究一下nacos NamingProxy的getServiceList
NamingProxy.initRefreshSrvIfNeed
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/net/NamingProxy.java
public class NamingProxy { private static final int DEFAULT_SERVER_PORT = 8848; private int serverPort = DEFAULT_SERVER_PORT; private String namespaceId; private String endpoint; private String nacosDomain; private List serverList; private List serversFromEndpoint = new ArrayList(); private long lastSrvRefTime = 0L; private long vipSrvRefInterMillis = TimeUnit.SECONDS.toMillis(30); private Properties properties; public NamingProxy(String namespaceId, String endpoint, String serverList) { this.namespaceId = namespaceId; this.endpoint = endpoint; if (StringUtils.isNotEmpty(serverList)) { this.serverList = Arrays.asList(serverList.split(",")); if (this.serverList.size() == 1) { this.nacosDomain = serverList; } } initRefreshSrvIfNeed(); } private void initRefreshSrvIfNeed() { if (StringUtils.isEmpty(endpoint)) { return; } ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1, new ThreadFactory() { @Override public Thread newThread(Runnable r) { Thread t = new Thread(r); t.setName("com.alibaba.nacos.client.naming.serverlist.updater"); t.setDaemon(true); return t; } }); executorService.scheduleWithFixedDelay(new Runnable() { @Override public void run() { refreshSrvIfNeed(); } }, 0, vipSrvRefInterMillis, TimeUnit.MILLISECONDS); refreshSrvIfNeed(); } //...... private void refreshSrvIfNeed() { try { if (!CollectionUtils.isEmpty(serverList)) { NAMING_LOGGER.debug("server list provided by user: " + serverList); return; } if (System.currentTimeMillis() - lastSrvRefTime < vipSrvRefInterMillis) { return; } List list = getServerListFromEndpoint(); if (CollectionUtils.isEmpty(list)) { throw new Exception("Can not acquire Nacos list"); } if (!CollectionUtils.isEqualCollection(list, serversFromEndpoint)) { NAMING_LOGGER.info("[SERVER-LIST] server list is updated: " + list); } serversFromEndpoint = list; lastSrvRefTime = System.currentTimeMillis(); } catch (Throwable e) { NAMING_LOGGER.warn("failed to update server list", e); } } public List getServerListFromEndpoint() { try { String urlString = "http://" + endpoint + "/nacos/serverlist"; List headers = builderHeaders(); HttpClient.HttpResult result = HttpClient.httpGet(urlString, headers, null, UtilAndComs.ENCODING); if (HttpURLConnection.HTTP_OK != result.code) { throw new IOException("Error while requesting: " + urlString + "'. Server returned: " + result.code); } String content = result.content; List list = new ArrayList(); for (String line : IoUtils.readLines(new StringReader(content))) { if (!line.trim().isEmpty()) { list.add(line.trim()); } } return list; } catch (Exception e) { e.printStackTrace(); } return null; } //......} NamingProxy的构造器执行了initRefreshSrvIfNeed方法，该方法在endpoint不为空的时候，会注册一个定时任务，每隔vipSrvRefInterMillis时间执行一次refreshSrvIfNeed方法，同时立马调用了refreshSrvIfNeed方法
refreshSrvIfNeed方法在serverList为空，且距离lastSrvRefTime大于等于vipSrvRefInterMillis时会通过getServerListFromEndpoint()方法获取serverList更新serversFromEndpoint及lastSrvRefTime
getServerListFromEndpoint方法会向endpoint请求/serverlist接口，获取server端返回的serverList
NamingProxy.getServiceList
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/net/NamingProxy.java
public class NamingProxy { private static final int DEFAULT_SERVER_PORT = 8848; private int serverPort = DEFAULT_SERVER_PORT; private String namespaceId; private String endpoint; private String nacosDomain; private List serverList; private List serversFromEndpoint = new ArrayList(); private long lastSrvRefTime = 0L; private long vipSrvRefInterMillis = TimeUnit.SECONDS.toMillis(30); private Properties properties; //...... public ListView getServiceList(int pageNo, int pageSize, String groupName) throws NacosException { return getServiceList(pageNo, pageSize, groupName, null); } public ListView getServiceList(int pageNo, int pageSize, String groupName, AbstractSelector selector) throws NacosException { Map params = new HashMap(4); params.put("pageNo", String.valueOf(pageNo)); params.put("pageSize", String.valueOf(pageSize)); params.put(CommonParams.NAMESPACE_ID, namespaceId); params.put(CommonParams.GROUP_NAME, groupName); if (selector != null) { switch (SelectorType.valueOf(selector.getType())) { case none: break; case label: ExpressionSelector expressionSelector = (ExpressionSelector) selector; params.put("selector", JSON.toJSONString(expressionSelector)); break; default: break; } } String result = reqAPI(UtilAndComs.NACOS_URL_BASE + "/service/list", params); JSONObject json = JSON.parseObject(result); ListView listView = new ListView(); listView.setCount(json.getInteger("count")); listView.setData(JSON.parseObject(json.getString("doms"), new TypeReference>() { })); return listView; } public String reqAPI(String api, Map params) throws NacosException { List snapshot = serversFromEndpoint; if (!CollectionUtils.isEmpty(serverList)) { snapshot = serverList; } return reqAPI(api, params, snapshot); } public String reqAPI(String api, Map params, List servers) { return reqAPI(api, params, servers, HttpMethod.GET); } public String reqAPI(String api, Map params, List servers, String method) { params.put(CommonParams.NAMESPACE_ID, getNamespaceId()); if (CollectionUtils.isEmpty(servers) && StringUtils.isEmpty(nacosDomain)) { throw new IllegalArgumentException("no server available"); } Exception exception = new Exception(); if (servers != null && !servers.isEmpty()) { Random random = new Random(System.currentTimeMillis()); int index = random.nextInt(servers.size()); for (int i = 0; i < servers.size(); i++) { String server = servers.get(index); try { return callServer(api, params, server, method); } catch (NacosException e) { exception = e; NAMING_LOGGER.error("request {} failed.", server, e); } catch (Exception e) { exception = e; NAMING_LOGGER.error("request {} failed.", server, e); } index = (index + 1) % servers.size(); } throw new IllegalStateException("failed to req API:" + api + " after all servers(" + servers + ") tried: " + exception.getMessage()); } for (int i = 0; i < UtilAndComs.REQUEST_DOMAIN_RETRY_COUNT; i++) { try { return callServer(api, params, nacosDomain); } catch (Exception e) { exception = e; NAMING_LOGGER.error("[NA] req api:" + api + " failed, server(" + nacosDomain, e); } } throw new IllegalStateException("failed to req API:/api/" + api + " after all servers(" + servers + ") tried: " + exception.getMessage()); } //......} getServiceList方法有个AbstractSelector参数，它会往请求的参数里头添加selector参数，目前label类型会添加ExpressionSelector，之后调用reqAPI方法请求/service/list接口
reqAPI方法首先将serversFromEndpoint赋值给snapshot，但是serverList不为空的情况下会重置snapshot为serverList，然后进行reqAPI请求
reqAPI方法会根据servers.size()随机一个index，然后以servers.size()为最大循环次数开始for循环，循环里头根据index获取server然后通过callServer请求，请求成功则跳出循环返回，请求失败则递增index并对servers.size()取余继续下次循环，如果都请求失败则最后抛出IllegalStateException
小结
NamingProxy的构造器执行了initRefreshSrvIfNeed方法，该方法在endpoint不为空的时候，会注册一个定时任务，每隔vipSrvRefInterMillis时间执行一次refreshSrvIfNeed方法
refreshSrvIfNeed方法在serverList为空，且距离lastSrvRefTime大于等于vipSrvRefInterMillis时会通过getServerListFromEndpoint()方法获取serverList更新serversFromEndpoint及lastSrvRefTime
getServiceList方法优先以serverList作为server端地址列表，如果它为空再以serversFromEndpoint为准，然后通过reqAPI方法请求的时候，随机选择一个server进行请求，最多请求server.size()次，请求成功则跳出循环返回，请求失败则递增index并对servers.size()取余继续下次循环，如果都请求失败则最后抛出IllegalStateException
到此，相信大家对"nacos NamingProxy中getServiceList的原理及用法"有了更深的了解，不妨来实际操作一番吧！这里是网站，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！
