如何理解ZookeeperDiscoveryAutoConfiguration

本篇文章为大家展示了如何理解ZookeeperDiscoveryAutoConfiguration，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。

主要研究一下ZookeeperDiscoveryAutoConfiguration

ZookeeperDiscoveryAutoConfiguration

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperDiscoveryAutoConfiguration.java

@Configuration@ConditionalOnBean(ZookeeperDiscoveryClientConfiguration.Marker.class)@ConditionalOnZookeeperDiscoveryEnabled@AutoConfigureBefore({ CommonsClientAutoConfiguration.class,                NoopDiscoveryClientAutoConfiguration.class })@AutoConfigureAfter({ ZookeeperDiscoveryClientConfiguration.class })public class ZookeeperDiscoveryAutoConfiguration {        @Autowired(required = false)        private ZookeeperDependencies zookeeperDependencies;        @Autowired        private CuratorFramework curator;        @Bean        @ConditionalOnMissingBean        public ZookeeperDiscoveryProperties zookeeperDiscoveryProperties(                        InetUtils inetUtils) {                return new ZookeeperDiscoveryProperties(inetUtils);        }        @Bean        @ConditionalOnMissingBean        // currently means auto-registration is false. That will change when        // ZookeeperServiceDiscovery is gone        public ZookeeperDiscoveryClient zookeeperDiscoveryClient(                        ServiceDiscovery serviceDiscovery,                        ZookeeperDiscoveryProperties zookeeperDiscoveryProperties) {                return new ZookeeperDiscoveryClient(serviceDiscovery, this.zookeeperDependencies,                                zookeeperDiscoveryProperties);        }        @Bean        public ZookeeperServiceWatch zookeeperServiceWatch(                        ZookeeperDiscoveryProperties zookeeperDiscoveryProperties) {                return new ZookeeperServiceWatch(this.curator, zookeeperDiscoveryProperties);        }        @Configuration        @ConditionalOnEnabledHealthIndicator("zookeeper")        @ConditionalOnClass(Endpoint.class)        protected static class ZookeeperDiscoveryHealthConfig {                @Autowired(required = false)                private ZookeeperDependencies zookeeperDependencies;                @Bean                @ConditionalOnMissingBean                public ZookeeperDiscoveryHealthIndicator zookeeperDiscoveryHealthIndicator(                                CuratorFramework curatorFramework,                                ServiceDiscovery serviceDiscovery,                                ZookeeperDiscoveryProperties properties) {                        return new ZookeeperDiscoveryHealthIndicator(curatorFramework,                                        serviceDiscovery, this.zookeeperDependencies, properties);                }        }}

• ZookeeperDiscoveryAutoConfiguration注册了ZookeeperDiscoveryProperties、ZookeeperDiscoveryClient、ZookeeperServiceWatch、ZookeeperDiscoveryHealthIndicator

ZookeeperDiscoveryProperties

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperDiscoveryProperties.java

@ConfigurationProperties("spring.cloud.zookeeper.discovery")public class ZookeeperDiscoveryProperties {        /**         * Default URI spec.         */        public static final String DEFAULT_URI_SPEC = "{scheme}://{address}:{port}";        private InetUtils.HostInfo hostInfo;        private boolean enabled = true;        /**         * Root Zookeeper folder in which all instances are registered.         */        private String root = "/services";        /**         * The URI specification to resolve during service registration in Zookeeper.         */        private String uriSpec = DEFAULT_URI_SPEC;        /** Id used to register with zookeeper. Defaults to a random UUID. */        private String instanceId;        /**         * Predefined host with which a service can register itself in Zookeeper. Corresponds         * to the {code address} from the URI spec.         */        private String instanceHost;        /**         * IP address to use when accessing service (must also set preferIpAddress to use).         */        private String instanceIpAddress;        /**         * Use ip address rather than hostname during registration.         */        private boolean preferIpAddress = false;        /** Port to register the service under (defaults to listening port). */        private Integer instancePort;        /** Ssl port of the registered service. */        private Integer instanceSslPort;        /**         * Register as a service in zookeeper.         */        private boolean register = true;        /**         * Gets the metadata name/value pairs associated with this instance. This information         * is sent to zookeeper and can be used by other instances.         */        private Map metadata = new HashMap<>();        /**         * The initial status of this instance (defaults to         * {@link StatusConstants#STATUS_UP}).         */        private String initialStatus = StatusConstants.STATUS_UP;        /**         * Order of the discovery client used by `CompositeDiscoveryClient` for sorting         * available clients.         */        private int order = 0;        //......}

• ZookeeperDiscoveryProperties定义了enabled、root、uriSpec、instanceId、instanceHost、instanceIpAddress、preferIpAddress、instancePort、instanceSslPort、register、metadata、initialStatus、order属性

ZookeeperDiscoveryClient

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperDiscoveryClient.java

public class ZookeeperDiscoveryClient implements DiscoveryClient {        private static final Log log = LogFactory.getLog(ZookeeperDiscoveryClient.class);        private final ZookeeperDependencies zookeeperDependencies;        private final ServiceDiscovery serviceDiscovery;        private final ZookeeperDiscoveryProperties zookeeperDiscoveryProperties;        public ZookeeperDiscoveryClient(ServiceDiscovery serviceDiscovery,                        ZookeeperDependencies zookeeperDependencies,                        ZookeeperDiscoveryProperties zookeeperDiscoveryProperties) {                this.serviceDiscovery = serviceDiscovery;                this.zookeeperDependencies = zookeeperDependencies;                this.zookeeperDiscoveryProperties = zookeeperDiscoveryProperties;        }        @Override        public String description() {                return "Spring Cloud Zookeeper Discovery Client";        }        private static org.springframework.cloud.client.ServiceInstance createServiceInstance(                        String serviceId, ServiceInstance serviceInstance) {                return new ZookeeperServiceInstance(serviceId, serviceInstance);        }        @Override        public List getInstances(                        final String serviceId) {                try {                        if (getServiceDiscovery() == null) {                                return Collections.EMPTY_LIST;                        }                        String serviceIdToQuery = getServiceIdToQuery(serviceId);                        Collection> zkInstances = getServiceDiscovery()                                        .queryForInstances(serviceIdToQuery);                        List instances = new ArrayList<>();                        for (ServiceInstance instance : zkInstances) {                                instances.add(createServiceInstance(serviceIdToQuery, instance));                        }                        return instances;                }                catch (KeeperException.NoNodeException e) {                        if (log.isDebugEnabled()) {                                log.debug(                                                "Error getting instances from zookeeper. Possibly, no service has registered.",                                                e);                        }                        // this means that nothing has registered as a service yes                        return Collections.emptyList();                }                catch (Exception exception) {                        rethrowRuntimeException(exception);                }                return new ArrayList<>();        }        private ServiceDiscovery getServiceDiscovery() {                return this.serviceDiscovery;        }        private String getServiceIdToQuery(String serviceId) {                if (this.zookeeperDependencies != null                                && this.zookeeperDependencies.hasDependencies()) {                        String pathForAlias = this.zookeeperDependencies.getPathForAlias(serviceId);                        return pathForAlias.isEmpty() ? serviceId : pathForAlias;                }                return serviceId;        }        @Override        public List getServices() {                List services = null;                if (getServiceDiscovery() == null) {                        log.warn(                                        "Service Discovery is not yet ready - returning empty list of services");                        return Collections.emptyList();                }                try {                        Collection names = getServiceDiscovery().queryForNames();                        if (names == null) {                                return Collections.emptyList();                        }                        services = new ArrayList<>(names);                }                catch (KeeperException.NoNodeException e) {                        if (log.isDebugEnabled()) {                                log.debug(                                                "Error getting services from zookeeper. Possibly, no service has registered.",                                                e);                        }                        // this means that nothing has registered as a service yes                        return Collections.emptyList();                }                catch (Exception e) {                        rethrowRuntimeException(e);                }                return services;        }        @Override        public int getOrder() {                return this.zookeeperDiscoveryProperties.getOrder();        }}

• ZookeeperDiscoveryClient实现了org.springframework.cloud.client.discovery.DiscoveryClient接口，其getInstances使用curator的ServiceDiscovery.queryForInstances获取服务实例信息，然后转换为org.springframework.cloud.client.ServiceInstance类型；getServices则是使用curator的ServiceDiscovery.queryForNames获取服务名信息

ZookeeperServiceWatch

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperServiceWatch.java

public class ZookeeperServiceWatch                implements ApplicationListener>, TreeCacheListener,                ApplicationEventPublisherAware {        private final CuratorFramework curator;        private final ZookeeperDiscoveryProperties properties;        private final AtomicLong cacheChange = new AtomicLong(0);        private ApplicationEventPublisher publisher;        private TreeCache cache;        public ZookeeperServiceWatch(CuratorFramework curator,                        ZookeeperDiscoveryProperties properties) {                this.curator = curator;                this.properties = properties;        }        @Override        public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {                this.publisher = publisher;        }        public TreeCache getCache() {                return this.cache;        }        @Override        public void onApplicationEvent(InstanceRegisteredEvent event) {                this.cache = TreeCache.newBuilder(this.curator, this.properties.getRoot())                                .build();                this.cache.getListenable().addListener(this);                try {                        this.cache.start();                }                catch (Exception e) {                        ReflectionUtils.rethrowRuntimeException(e);                }        }        @PreDestroy        public void stop() throws Exception {                if (this.cache != null) {                        this.cache.close();                }        }        @Override        public void childEvent(CuratorFramework client, TreeCacheEvent event)                        throws Exception {                if (event.getType().equals(TreeCacheEvent.Type.NODE_ADDED)                                || event.getType().equals(TreeCacheEvent.Type.NODE_REMOVED)                                || event.getType().equals(TreeCacheEvent.Type.NODE_UPDATED)) {                        long newCacheChange = this.cacheChange.incrementAndGet();                        this.publisher.publishEvent(new HeartbeatEvent(this, newCacheChange));                }        }}

• ZookeeperServiceWatch实现了ApplicationListener、TreeCacheListener、ApplicationEventPublisherAware接口；其childEvent方法在event类型是NODE_ADDED、NODE_REMOVED、NODE_UPDATED类型时会发布HeartbeatEvent事件

ZookeeperDiscoveryHealthIndicator

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperDiscoveryHealthIndicator.java

public class ZookeeperDiscoveryHealthIndicator implements DiscoveryHealthIndicator {        private static final Log log = LogFactory                        .getLog(ZookeeperDiscoveryHealthIndicator.class);        private CuratorFramework curatorFramework;        private ServiceDiscovery serviceDiscovery;        private final ZookeeperDependencies zookeeperDependencies;        private final ZookeeperDiscoveryProperties zookeeperDiscoveryProperties;        public ZookeeperDiscoveryHealthIndicator(CuratorFramework curatorFramework,                        ServiceDiscovery serviceDiscovery,                        ZookeeperDependencies zookeeperDependencies,                        ZookeeperDiscoveryProperties zookeeperDiscoveryProperties) {                this.curatorFramework = curatorFramework;                this.serviceDiscovery = serviceDiscovery;                this.zookeeperDependencies = zookeeperDependencies;                this.zookeeperDiscoveryProperties = zookeeperDiscoveryProperties;        }        @Override        public String getName() {                return "zookeeper";        }        @Override        public Health health() {                Health.Builder builder = Health.unknown();                try {                        Iterable> allInstances = new ZookeeperServiceInstances(                                        this.curatorFramework, this.serviceDiscovery,                                        this.zookeeperDependencies, this.zookeeperDiscoveryProperties);                        builder.up().withDetail("services", allInstances);                }                catch (Exception e) {                        log.error("Error", e);                        builder.down(e);                }                return builder.build();        }}

• ZookeeperDiscoveryHealthIndicator实现了DiscoveryHealthIndicator接口，其health方法创建ZookeeperServiceInstances

ZookeeperServiceInstances

spring-cloud-zookeeper-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/zookeeper/discovery/ZookeeperServiceInstances.java

public class ZookeeperServiceInstances                implements Iterable> {        private static final Log log = LogFactory.getLog(ZookeeperServiceInstances.class);        private ServiceDiscovery serviceDiscovery;        private final ZookeeperDependencies zookeeperDependencies;        private final ZookeeperDiscoveryProperties zookeeperDiscoveryProperties;        private final List> allInstances;        private final CuratorFramework curator;        public ZookeeperServiceInstances(CuratorFramework curator,                        ServiceDiscovery serviceDiscovery,                        ZookeeperDependencies zookeeperDependencies,                        ZookeeperDiscoveryProperties zookeeperDiscoveryProperties) {                this.curator = curator;                this.serviceDiscovery = serviceDiscovery;                this.zookeeperDependencies = zookeeperDependencies;                this.zookeeperDiscoveryProperties = zookeeperDiscoveryProperties;                this.allInstances = getZookeeperInstances();        }        private List> getZookeeperInstances() {                ArrayList> allInstances = new ArrayList<>();                try {                        Collection namesToQuery = getNamesToQuery();                        if (log.isDebugEnabled()) {                                log.debug("Querying the following names [" + namesToQuery + "]");                        }                        for (String name : namesToQuery) {                                allInstances.addAll(nestedInstances(allInstances, name));                        }                        return allInstances;                }                catch (Exception e) {                        log.debug("Exception occurred while trying to build the list of instances",                                        e);                        return allInstances;                }        }        //......}

• ZookeeperServiceInstances的构造器会调用getZookeeperInstances拉取ServiceInstance

小结

ZookeeperDiscoveryAutoConfiguration注册了ZookeeperDiscoveryProperties、ZookeeperDiscoveryClient、ZookeeperServiceWatch、ZookeeperDiscoveryHealthIndicator

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