补充注释

spring-boot-admin-server-cloud/src/main/java/de/codecentric/boot/admin/server/cloud/discovery/InstanceDiscoveryListener.java

@@ -27,6 +27,7 @@ import reactor.core.publisher.Mono;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -43,6 +44,8 @@ import org.springframework.util.PatternMatchUtils;
 /**
  * Listener for Heartbeats events to publish all services to the instance registry.
  *
+ * 监听Heartbeats事件以将所有服务发布到实例注册表。
+ *
  * @author Johannes Edmeier
  */
 public class InstanceDiscoveryListener {
@@ -89,6 +92,10 @@ public class InstanceDiscoveryListener {
         discoverIfNeeded(event.getValue());
     }
 
+    /**
+     * 监听eureka的心跳
+     * @param event
+     */
     @EventListener
     public void onApplicationEvent(HeartbeatEvent event) {
         discoverIfNeeded(event.getValue());
@@ -101,13 +108,31 @@ public class InstanceDiscoveryListener {
     }
 
     protected void discover() {
+        // 开始进行发现逻辑，获取所有注册上去的服务
         Flux.fromIterable(discoveryClient.getServices())
+            // 是否需要进行注册，可以控制有的服务不被发现
             .filter(this::shouldRegisterService)
-            .flatMapIterable(discoveryClient::getInstances)
-            .flatMap(this::registerInstance)
+            .flatMapIterable(new Function<String, Iterable<ServiceInstance>>() {
+                @Override
+                public Iterable<ServiceInstance> apply(String s) {
+                    return discoveryClient.getInstances(s);
+                }
+            })
+            .flatMap(new Function<ServiceInstance, Mono<InstanceId>>() {
+                @Override
+                public Mono<InstanceId> apply(ServiceInstance serviceInstance) {
+                    return registerInstance(serviceInstance);
+                }
+            })
             .collect(Collectors.toSet())
-            .flatMap(this::removeStaleInstances)
-            .subscribe(v -> { }, ex -> log.error("Unexpected error.", ex));
+            .flatMap(new Function<Set<InstanceId>, Mono<Void>>() {
+                @Override
+                public Mono<Void> apply(Set<InstanceId> objects) {
+                    return removeStaleInstances(objects);
+                }
+            })
+            .subscribe(v -> {
+            }, ex -> log.error("Unexpected error.", ex));
     }
 
     protected Mono<Void> removeStaleInstances(Set<InstanceId> registeredInstanceIds) {

spring-boot-admin-server/src/main/java/de/codecentric/boot/admin/server/services/InstanceRegistry.java

@@ -48,12 +48,16 @@ public class InstanceRegistry {
      */
     public Mono<InstanceId> register(Registration registration) {
         Assert.notNull(registration, "'registration' must not be null");
+        // 通过某种算法生成InstanceId
         InstanceId id = generator.generateId(registration);
         Assert.notNull(id, "'id' must not be null");
+        // 然后更新这个id对应的实例信息
         return repository.compute(id, (key, instance) -> {
+            // 如果这个对应的实例信息为空，会创建一个信息实例上去
             if (instance == null) {
                 instance = Instance.create(key);
             }
+            // 然后把注册实例注册上去
             return Mono.just(instance.register(registration));
         }).map(Instance::getId);
     }