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6 nacos注册中心之服务地址的查询
nacos的服务端给我们提供了获取注册中心中服务地址的查询api，对应的Open API如下：
发送get请求
http://127.0.0.1:848/nacos/v1/ns/instance/list?serviceName=example
下载nacos服务端的源码，我们找到InstanceController类，有关实例的接口都在这个类中，我们从调用的api找到对应的Controller层
查询服务地址的方法是对应InstanceController的list方法：
InstanceController的list()方法
@GetMapping("/list")
public JSONObject list(HttpServletRequest request) throws Exception {
String namespaceId = WebUtils.optional(request, CommonParams.NAMESPACE_ID,
Constants.DEFAULT_NAMESPACE_ID);
String serviceName = WebUtils.required(request, CommonParams.SERVICE_NAME);
String agent = WebUtils.getUserAgent(request);
String clusters = WebUtils.optional(request, "clusters", StringUtils.EMPTY);
String clientIP = WebUtils.optional(request, "clientIP", StringUtils.EMPTY);
Integer udpPort = Integer.parseInt(WebUtils.optional(request, "udpPort", "0"));
String env = WebUtils.optional(request, "env", StringUtils.EMPTY);
boolean isCheck = Boolean.parseBoolean(WebUtils.optional(request, "isCheck", "false"));
String app = WebUtils.optional(request, "app", StringUtils.EMPTY);
String tenant = WebUtils.optional(request, "tid", StringUtils.EMPTY);
boolean healthyOnly = Boolean.parseBoolean(WebUtils.optional(request, "healthyOnly", "false"));
return doSrvIPXT(namespaceId, serviceName, agent, clusters, clientIP, udpPort, env, isCheck, app, tenant,
healthyOnly);
}
- 解析请求参数，包括namespaceId、服务名、代理、集群、客户端ip等等信息
- 通过doSrvIPXT()方法返回服务列表数据
我们看一下doSrvIPXT()方法中做了什么
doSrvIPXT()方法
doSrvIPXT()方法的主要功能是获取服务信息和所有的节点内容
public JSONObject doSrvIPXT(String namespaceId, String serviceName, String agent, String clusters, String clientIP,
int udpPort,
String env, boolean isCheck, String app, String tid, boolean healthyOnly)
throws Exception {
ClientInfo clientInfo = new ClientInfo(agent);
JSONObject result = new JSONObject();
Service service = serviceManager.getService(namespaceId, serviceName);
if (service == null) {
if (Loggers.SRV_LOG.isDebugEnabled()) {
Loggers.SRV_LOG.debug("no instance to serve for service: {}", serviceName);
}
result.put("name", serviceName);
result.put("clusters", clusters);
result.put("hosts", new JSONArray());
return result;
}
checkIfDisabled(service);
long cacheMillis = switchDomain.getDefaultCacheMillis();
// now try to enable the push
try {
if (udpPort > 0 && pushService.canEnablePush(agent)) {
pushService.addClient(namespaceId, serviceName,
clusters,
agent,
new InetSocketAddress(clientIP, udpPort),
pushDataSource,
tid,
app);
cacheMillis = switchDomain.getPushCacheMillis(serviceName);
}
} catch (Exception e) {
Loggers.SRV_LOG.error("[NACOS-API] failed to added push client", e);
cacheMillis = switchDomain.getDefaultCacheMillis();
}
List<Instance> srvedIPs;
srvedIPs = service.srvIPs(Arrays.asList(StringUtils.split(clusters, ",")));
// filter ips using selector:
if (service.getSelector() != null && StringUtils.isNotBlank(clientIP)) {
srvedIPs = service.getSelector().select(clientIP, srvedIPs);
}
if (CollectionUtils.isEmpty(srvedIPs)) {
if (Loggers.SRV_LOG.isDebugEnabled()) {
Loggers.SRV_LOG.debug("no instance to serve for service: {}", serviceName);
}
if (clientInfo.type == ClientInfo.ClientType.JAVA &&
clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {
result.put("dom", serviceName);
} else {
result.put("dom", NamingUtils.getServiceName(serviceName));
}
result.put("hosts", new JSONArray());
result.put("name", serviceName);
result.put("cacheMillis", cacheMillis);
result.put("lastRefTime", System.currentTimeMillis());
result.put("checksum", service.getChecksum());
result.put("useSpecifiedURL", false);
result.put("clusters", clusters);
result.put("env", env);
result.put("metadata", service.getMetadata());
return result;
}
Map<Boolean, List<Instance>> ipMap = new HashMap<>(2);
ipMap.put(Boolean.TRUE, new ArrayList<>());
ipMap.put(Boolean.FALSE, new ArrayList<>());
for (Instance ip : srvedIPs) {
ipMap.get(ip.isHealthy()).add(ip);
}
if (isCheck) {
result.put("reachProtectThreshold", false);
}
double threshold = service.getProtectThreshold();
if ((float) ipMap.get(Boolean.TRUE).size() / srvedIPs.size() <= threshold) {
Loggers.SRV_LOG.warn("protect threshold reached, return all ips, service: {}", serviceName);
if (isCheck) {
result.put("reachProtectThreshold", true);
}
ipMap.get(Boolean.TRUE).addAll(ipMap.get(Boolean.FALSE));
ipMap.get(Boolean.FALSE).clear();
}
if (isCheck) {
result.put("protectThreshold", service.getProtectThreshold());
result.put("reachLocalSiteCallThreshold", false);
return new JSONObject();
}
JSONArray hosts = new JSONArray();
for (Map.Entry<Boolean, List<Instance>> entry : ipMap.entrySet()) {
List<Instance> ips = entry.getValue();
if (healthyOnly && !entry.getKey()) {
continue;
}
for (Instance instance : ips) {
// remove disabled instance:
if (!instance.isEnabled()) {
continue;
}
JSONObject ipObj = new JSONObject();
ipObj.put("ip", instance.getIp());
ipObj.put("port", instance.getPort());
// deprecated since nacos 1.0.0:
ipObj.put("valid", entry.getKey());
ipObj.put("healthy", entry.getKey());
ipObj.put("marked", instance.isMarked());
ipObj.put("instanceId", instance.getInstanceId());
ipObj.put("metadata", instance.getMetadata());
ipObj.put("enabled", instance.isEnabled());
ipObj.put("weight", instance.getWeight());
ipObj.put("clusterName", instance.getClusterName());
if (clientInfo.type == ClientInfo.ClientType.JAVA &&
clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {
ipObj.put("serviceName", instance.getServiceName());
} else {
ipObj.put("serviceName", NamingUtils.getServiceName(instance.getServiceName()));
}
ipObj.put("ephemeral", instance.isEphemeral());
hosts.add(ipObj);
}
}
result.put("hosts", hosts);
if (clientInfo.type == ClientInfo.ClientType.JAVA &&
clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {
result.put("dom", serviceName);
} else {
result.put("dom", NamingUtils.getServiceName(serviceName));
}
result.put("name", serviceName);
result.put("cacheMillis", cacheMillis);
result.put("lastRefTime", System.currentTimeMillis());
result.put("checksum", service.getChecksum());
result.put("useSpecifiedURL", false);
result.put("clusters", clusters);
result.put("env", env);
result.put("metadata", service.getMetadata());
return result;
}
代码虽然有点长，但内容非常好理解，主要做三件事：
- 调用serviceManager.getService()方法根据传入的namespaceId serviceName获得Service实例，如果获得的实例为空，就打印没有相关实例的日志，并返回结果，如果Service实例不为空，执行下面的逻辑
- 检查Service是否禁用
- 试着开启推送，添加推送的客户端
- 从Service实例中调用srvIPs方法得到所有服务提供者的实例信息。
- 使用过滤器来获取到的实例信息
- 遍历组装JSON字符串并返回。
总结
这就是nacos的服务查询功能呢，对应接口就是这个
get请求
http://127.0.0.1:848/nacos/v1/ns/instance/list?serviceName=example
整体逻辑 深入源码，了解它的本质，它的实现也比较好理解，和我们经常开发的Controller等业务服务差不多，核心代码就是通过srvIPs()方法来获取实例列表，然后封装成JSON，返回给客户端，让我们一起学习，一起进步，一起了解nacos源码
