Dubbo服务暴露注册原理

叔牙 • 2023-01-02 • 云技术社区 • 262 阅读

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一、概述

dubbo是java领域应用最广泛的rpc框架之一,服务端启动时把服务注册到注册中心,客户端启动时向注册中心订阅服务,然后通过客户端的负载和路由机器选择对应的服务进行连接调用。

通过上图我们可以看出,对于服务端,如果想要被调用,需要把自己注册到注册中心,以便于客户端能发现,对于客户端,需要把自己需要调用的服务订阅到注册中心。就好比,工厂生产的东西,放到商店才能够被别人购买,同样客户去商店买东西,要告诉商店想要买什么。

本篇文章将会详细的介绍dubbo服务的暴露注册流程和原理。

在分析之前还要搬一张dubbo的图,来对服务注册有一个大致的认识和概念:

注意看右半边浅绿色部分,涉及到了服务注册和服务调用,官方也给出了服务暴露的时序图:

但是只能说比较抽象和宽泛,具体的细节和实现思路还需要我们自己去理解和领会。

接下来我们将详细地分析dubbo服务暴露注册的原理。

注意

dubbo版本2.7.8

二、原理&源码分析

为了理解方便,我们将原理拆分成两部分来介绍,分别是服务实例化和服务暴露注册。

1.服务实例化

从EnableDubbo开始看:

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
@EnableDubboConfig
@DubboComponentScan
public @interface EnableDubbo {
    @AliasFor(annotation = DubboComponentScan.class, attribute = "basePackages")
    String[] scanBasePackages() default {};
    @AliasFor(annotation = DubboComponentScan.class, attribute = "basePackageClasses")
    Class<?>[] scanBasePackageClasses() default {};
    @AliasFor(annotation = EnableDubboConfig.class, attribute = "multiple")
    boolean multipleConfig() default true;
}

定义扫描的包路径,并且EnableDubbo是一个组合注解,被另外两个注解@EnableDubboConfig和@DubboComponentScan标注,@EnableDubboConfig是配置相关并注册一些基础组件BeanDefinition,暂且不管,看一下@DubboComponentScan注解。

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(DubboComponentScanRegistrar.class)
public @interface DubboComponentScan {
    String[] value() default {};
    String[] basePackages() default {};
    Class<?>[] basePackageClasses() default {};
}

该注解导入了DubboComponentScanRegistrar,是一个ImportBeanDefinitionRegistrar,容器启动时会被ConfigurationClassPostProcessor调用,可参考《ImportBeanDefinitionRegistrar原理》,DubboComponentScanRegistrar重写registerBeanDefinitions方法:

@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
    Set<String> packagesToScan = getPackagesToScan(importingClassMetadata);
    registerServiceAnnotationBeanPostProcessor(packagesToScan, registry);
    // @since 2.7.6 Register the common beans
    registerCommonBeans(registry);
}

先获取要扫描的包路径,然后注册ServiceAnnotationBeanPostProcessor类的BeanDefinition:

private void registerServiceAnnotationBeanPostProcessor(Set<String> packagesToScan, BeanDefinitionRegistry registry) {
    BeanDefinitionBuilder builder = rootBeanDefinition(ServiceAnnotationBeanPostProcessor.class);
    builder.addConstructorArgValue(packagesToScan);
    builder.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
    AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
    BeanDefinitionReaderUtils.registerWithGeneratedName(beanDefinition, registry);
}

ServiceAnnotationBeanPostProcessor是BeanFactoryProcessor也是BeanDefinitionRegistryPostProcessor,在AbstractApplicationContext#refresh刷新上下文之后会调用其

postProcessBeanDefinitionRegistry方法。看一下方法定义:

@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
    // @since 2.7.5
    registerInfrastructureBean(registry, DubboBootstrapApplicationListener.BEAN_NAME, DubboBootstrapApplicationListener.class);
    Set<String> resolvedPackagesToScan = resolvePackagesToScan(packagesToScan);
    if (!CollectionUtils.isEmpty(resolvedPackagesToScan)) {
        registerServiceBeans(resolvedPackagesToScan, registry);
    } 
}

先注册了DubboBootstrapApplicationListener类定义(后边分析服务注册会用到),然后调用registerServiceBeans方法注册ServiceBean:

private void registerServiceBeans(Set<String> packagesToScan, BeanDefinitionRegistry registry) {
    DubboClassPathBeanDefinitionScanner scanner =
            new DubboClassPathBeanDefinitionScanner(registry, environment, resourceLoader);
    BeanNameGenerator beanNameGenerator = resolveBeanNameGenerator(registry);
    scanner.setBeanNameGenerator(beanNameGenerator);
    // refactor @since 2.7.7
    serviceAnnotationTypes.forEach(annotationType -> {
        scanner.addIncludeFilter(new AnnotationTypeFilter(annotationType));
    });
    for (String packageToScan : packagesToScan) {
        // Registers @Service Bean first
        scanner.scan(packageToScan);
        // Finds all BeanDefinitionHolders of @Service whether @ComponentScan scans or not.
        Set<BeanDefinitionHolder> beanDefinitionHolders =
                findServiceBeanDefinitionHolders(scanner, packageToScan, registry, beanNameGenerator);
        if (!CollectionUtils.isEmpty(beanDefinitionHolders)) {
            for (BeanDefinitionHolder beanDefinitionHolder : beanDefinitionHolders) {
                registerServiceBean(beanDefinitionHolder, registry, scanner);
            }
        }
    }
}

在指定包路径下扫描所支持服务注解的类,然后调用registerServiceBean逐个注册成ServiceBean:

private void registerServiceBean(BeanDefinitionHolder beanDefinitionHolder, BeanDefinitionRegistry registry,
                                 DubboClassPathBeanDefinitionScanner scanner) {
    Class<?> beanClass = resolveClass(beanDefinitionHolder);
    Annotation service = findServiceAnnotation(beanClass);
    AnnotationAttributes serviceAnnotationAttributes = getAnnotationAttributes(service, false, false);
    Class<?> interfaceClass = resolveServiceInterfaceClass(serviceAnnotationAttributes, beanClass);
    String annotatedServiceBeanName = beanDefinitionHolder.getBeanName();
    AbstractBeanDefinition serviceBeanDefinition =
            buildServiceBeanDefinition(service, serviceAnnotationAttributes, interfaceClass, annotatedServiceBeanName);
    String beanName = generateServiceBeanName(serviceAnnotationAttributes, interfaceClass);
    if (scanner.checkCandidate(beanName, serviceBeanDefinition)) { // check duplicated candidate bean
        registry.registerBeanDefinition(beanName, serviceBeanDefinition);
    } 
}

该方法将扫描得到的BeanDefinition包装转换成ServiceBean然后注册到容器中:

private AbstractBeanDefinition buildServiceBeanDefinition(Annotation serviceAnnotation,
                                                          AnnotationAttributes serviceAnnotationAttributes,
                                                          Class<?> interfaceClass,
                                                          String annotatedServiceBeanName) {
    BeanDefinitionBuilder builder = rootBeanDefinition(ServiceBean.class);
    AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
    //省略···
    return builder.getBeanDefinition();
}

到这里我们可以看到,改BeanFactoryProcessor回把我们应用中使用Service和DubboService标注的接口注册成ServiceBean类型的BeanDefinition;目前服务暴露支持三个注解:

private final static List<Class<? extends Annotation>> serviceAnnotationTypes = asList(
        // @since 2.7.7 Add the @DubboService , the issue : https://github.com/apache/dubbo/issues/6007
        DubboService.class,
        // @since 2.7.0 the substitute @com.alibaba.dubbo.config.annotation.Service
        Service.class,
        // @since 2.7.3 Add the compatibility for legacy Dubbo's @Service , the issue : https://github.com/apache/dubbo/issues/4330
        com.alibaba.dubbo.config.annotation.Service.class
);

在AbstractApplicationContext#refresh最后会调用finishBeanFactoryInitialization方法完成普通BeanDefinition的实例化。

然后我们看一下ServiceBean是个什么东东.

从继承关系中分析出,服务暴露在ServiceConfig中实现,并且在父类AbstractConfig中定义了初始化方法addInfoConfigManager.

@PostConstruct
public void addIntoConfigManager() {
    ApplicationModel.getConfigManager().addConfig(this);
}

在之前文章《spring bean生命周期管理》中有分析到@PostConstruct会在bean实例化之后,InitializingBean和自定义init方法之前执行。

该方法执行后,会把ServiceBean实例添加到ConfigManager中的configsCache缓存中等后续备用。

到这里,ServiceBean实例化就完成了,整个流程大致如下:

2.服务暴露注册

服务的暴露与注册是两个不同的概念;在Dubbo中，微服务之间的交互默认是通过Netty进行的，而服务之间的通信是基于TCP方式进行的。也就是说，每个服务都会存在一个ip和port。所谓的服务暴露就是指根据配置将当前服务使用Netty绑定一个本地的端口号(对于消费者而言，则是尝试连接目标服务的ip和端口)。至于注册，由于微服务架构中对于新添加的服务，需要一定的机制来通知消费者，有新的服务可用，或者对于某些下线的服务，也需要通知消费者，将这个已经下线的服务给移除。

前边有说过ServiceClassPostProcessor会注册DubboBootstrapApplicationListener类定义,应用启动会初始化。

它是一个ApplicationListener,会接受Spring容器的事件,重写onApplicationContextEvent接收上下文刷新和上下文关闭事件:

@Override
public void onApplicationContextEvent(ApplicationContextEvent event) {
    if (event instanceof ContextRefreshedEvent) {
        onContextRefreshedEvent((ContextRefreshedEvent) event);
    } else if (event instanceof ContextClosedEvent) {
        onContextClosedEvent((ContextClosedEvent) event);
    }
}

处理接收到上下文刷新成功事件调用了DubboBootstrap的start方法:

public DubboBootstrap start() {
    if (started.compareAndSet(false, true)) {
        ready.set(false);
        initialize();
        if (logger.isInfoEnabled()) {
            logger.info(NAME + " is starting...");
        }
        // 1. export Dubbo Services
        exportServices();
        //省略
    }
    return this;
}

做一些初始化操作之后调用exportServices导出服务:

private void exportServices() {
    configManager.getServices().forEach(sc -> {
        ServiceConfig serviceConfig = (ServiceConfig) sc;
        serviceConfig.setBootstrap(this);
        if (exportAsync) {
            ExecutorService executor = executorRepository.getServiceExporterExecutor();
            Future<?> future = executor.submit(() -> {
                sc.export();
                exportedServices.add(sc);
            });
            asyncExportingFutures.add(future);
        } else {
            sc.export();
            exportedServices.add(sc);
        }
    });
}

这里会用到前边我们分析的ServiceBean实例化之后会调用@PostConstruct将其添加到ConfigManager中,这里会拿到ServiceBean实例列表遍历,然后调用export方法,会调用ServiceBean的父类ServiceConfig的export方法:

public synchronized void export() {
    if (!shouldExport()) {
        return;
    }
    if (bootstrap == null) {
        bootstrap = DubboBootstrap.getInstance();
        bootstrap.initialize();
    }
    checkAndUpdateSubConfigs();
    //init serviceMetadata
    serviceMetadata.setVersion(getVersion());
    serviceMetadata.setGroup(getGroup());
    serviceMetadata.setDefaultGroup(getGroup());
    serviceMetadata.setServiceType(getInterfaceClass());
    serviceMetadata.setServiceInterfaceName(getInterface());
    serviceMetadata.setTarget(getRef());
    if (shouldDelay()) {
        DELAY_EXPORT_EXECUTOR.schedule(this::doExport, getDelay(), TimeUnit.MILLISECONDS);
    } else {
        doExport();
    }
    exported();
}

然后调用内部方法doExportUrlsFor1Protocol导出服务:

private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
    //省略
    // export service
    String scope = url.getParameter(SCOPE_KEY);
    // don't export when none is configured
    if (!SCOPE_NONE.equalsIgnoreCase(scope)) {
        // export to local if the config is not remote (export to remote only when config is remote)
        if (!SCOPE_REMOTE.equalsIgnoreCase(scope)) {
            exportLocal(url);
        }
        // export to remote if the config is not local (export to local only when config is local)
        if (!SCOPE_LOCAL.equalsIgnoreCase(scope)) {
            if (CollectionUtils.isNotEmpty(registryURLs)) {
                for (URL registryURL : registryURLs) {
                    //if protocol is only injvm ,not register
                    if (LOCAL_PROTOCOL.equalsIgnoreCase(url.getProtocol())) {
                        continue;
                    }
                    url = url.addParameterIfAbsent(DYNAMIC_KEY, registryURL.getParameter(DYNAMIC_KEY));
                    URL monitorUrl = ConfigValidationUtils.loadMonitor(this, registryURL);
                    if (monitorUrl != null) {
                        url = url.addParameterAndEncoded(MONITOR_KEY, monitorUrl.toFullString());
                    }
                    // For providers, this is used to enable custom proxy to generate invoker
                    String proxy = url.getParameter(PROXY_KEY);
                    if (StringUtils.isNotEmpty(proxy)) {
                        registryURL = registryURL.addParameter(PROXY_KEY, proxy);
                    }
                    Invoker<?> invoker = PROXY_FACTORY.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(EXPORT_KEY, url.toFullString()));
                    DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
                    Exporter<?> exporter = PROTOCOL.export(wrapperInvoker);
                    exporters.add(exporter);
                }
            } else {
                Invoker<?> invoker = PROXY_FACTORY.getInvoker(ref, (Class) interfaceClass, url);
                DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);

                Exporter<?> exporter = PROTOCOL.export(wrapperInvoker);
                exporters.add(exporter);
            }
        }
    }
    this.urls.add(url);
}

重点是PROTOCOL.export调用,Protocol是自定义扩展实现,常见的有InjvmProtocol、DubboProtocol和RegistryProtocol,RegistryProtocol不是真正的协议,是其他类型实现的包装,因为我们需要向注册中心注册服务,所以会调用RegistryProtocol实现:

@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
    URL registryUrl = getRegistryUrl(originInvoker);
    // url to export locally
    URL providerUrl = getProviderUrl(originInvoker);
    final URL overrideSubscribeUrl = getSubscribedOverrideUrl(providerUrl);
    final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
    overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
    providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
    //export invoker
    final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
    // url to registry
    final Registry registry = getRegistry(originInvoker);
    final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);
    boolean register = providerUrl.getParameter(REGISTER_KEY, true);
    if (register) {
        register(registryUrl, registeredProviderUrl);
    }
    //省略
    return new DestroyableExporter<>(exporter);
}

该方法有两个核心功能,调用doLocalExport暴露服务和调用register注册服务。先看一下暴露服务实现:

private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker, URL providerUrl) {
    String key = getCacheKey(originInvoker);
    return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {
        Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);
        return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);
    });
}

这里protocol.export会调用DubboProtocol实现:

@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
    URL url = invoker.getUrl();
    // export service.
    String key = serviceKey(url);
    DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
    exporterMap.put(key, exporter);
    //export an stub service for dispatching event
    Boolean isStubSupportEvent = url.getParameter(STUB_EVENT_KEY, DEFAULT_STUB_EVENT);
    Boolean isCallbackservice = url.getParameter(IS_CALLBACK_SERVICE, false);
    openServer(url);
    optimizeSerialization(url);
    return exporter;
}

openServer其实是进行服务的本地暴露,本质上就是根据配置使用Netty绑定本地的某个端口,从而完成服务暴露工作。然后调用到

@Override
public ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
    return new HeaderExchangeServer(Transporters.bind(url, new DecodeHandler(new HeaderExchangeHandler(handler))));
}

最后会调用到Dubbo封装的NettyServer的构造方法。

NettyServer会调用父类的构造方法:

public AbstractServer(URL url, ChannelHandler handler) throws RemotingException {
    super(url, handler);
    localAddress = getUrl().toInetSocketAddress();

    String bindIp = getUrl().getParameter(Constants.BIND_IP_KEY, getUrl().getHost());
    int bindPort = getUrl().getParameter(Constants.BIND_PORT_KEY, getUrl().getPort());
    if (url.getParameter(ANYHOST_KEY, false) || NetUtils.isInvalidLocalHost(bindIp)) {
        bindIp = ANYHOST_VALUE;
    }
    bindAddress = new InetSocketAddress(bindIp, bindPort);
    this.accepts = url.getParameter(ACCEPTS_KEY, DEFAULT_ACCEPTS);
    this.idleTimeout = url.getParameter(IDLE_TIMEOUT_KEY, DEFAULT_IDLE_TIMEOUT);
    try {
        doOpen();
    } catch (Throwable t) {
        throw new RemotingException(url.toInetSocketAddress(), null, "Failed to bind " + getClass().getSimpleName()
                + " on " + getLocalAddress() + ", cause: " + t.getMessage(), t);
    }
    executor = executorRepository.createExecutorIfAbsent(url);
}

然后会调用NettyServer的doOpen实现开启服务:

@Override
protected void doOpen() throws Throwable {
    bootstrap = new ServerBootstrap();
    bossGroup = NettyEventLoopFactory.eventLoopGroup(1, "NettyServerBoss");
    workerGroup = NettyEventLoopFactory.eventLoopGroup(
            getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS),
            "NettyServerWorker");
    final NettyServerHandler nettyServerHandler = new NettyServerHandler(getUrl(), this);
    channels = nettyServerHandler.getChannels();
    bootstrap.group(bossGroup, workerGroup)
            .channel(NettyEventLoopFactory.serverSocketChannelClass())
            .option(ChannelOption.SO_REUSEADDR, Boolean.TRUE)
            .childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE)
            .childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
            .childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    // FIXME: should we use getTimeout()?
                    int idleTimeout = UrlUtils.getIdleTimeout(getUrl());
                    NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);
                    if (getUrl().getParameter(SSL_ENABLED_KEY, false)) {
                        ch.pipeline().addLast("negotiation",
                                SslHandlerInitializer.sslServerHandler(getUrl(), nettyServerHandler));
                    }
                    ch.pipeline()
                            .addLast("decoder", adapter.getDecoder())
                            .addLast("encoder", adapter.getEncoder())
                            .addLast("server-idle-handler", new IdleStateHandler(0, 0, idleTimeout, MILLISECONDS))
                            .addLast("handler", nettyServerHandler);
                }
            });
    // bind
    ChannelFuture channelFuture = bootstrap.bind(getBindAddress());
    channelFuture.syncUninterruptibly();
    channel = channelFuture.channel();
}

这段代码看起来应该比较熟悉,就是开启netty服务,并且会添加一些编解码组件,服务调用处理组件等。

然后接着看服务注册register方法实现:

private void register(URL registryUrl, URL registeredProviderUrl) {
    Registry registry = registryFactory.getRegistry(registryUrl);
    registry.register(registeredProviderUrl);
}

注册中心我们选择Nacos进行分析,RegistryFactory会生成NacosRegistry并返回。

register会调用父类FailbackRegistry实现:

@Override
public void register(URL url) {
    if (!acceptable(url)) {
        return;
    }
    super.register(url);
    removeFailedRegistered(url);
    removeFailedUnregistered(url);
    try {
        // Sending a registration request to the server side
        doRegister(url);
    } catch (Exception e) {
        //省略
    }
}

然后就调用到子类NacosRegistry的doRegister实现:

@Override
public void doRegister(URL url) {
    final String serviceName = getServiceName(url);
    final Instance instance = createInstance(url);

    execute(namingService -> namingService.registerInstance(serviceName,
            getUrl().getParameter(GROUP_KEY, Constants.DEFAULT_GROUP), instance));
}

接着调用NamingProxy#registerService注册服务:

public void registerService(String serviceName, String groupName, Instance instance) throws NacosException {
    final Map<String, String> params = new HashMap<String, String>(16);
    params.put(CommonParams.NAMESPACE_ID, namespaceId);
    params.put(CommonParams.SERVICE_NAME, serviceName);
    params.put(CommonParams.GROUP_NAME, groupName);
    params.put(CommonParams.CLUSTER_NAME, instance.getClusterName());
    params.put("ip", instance.getIp());
    params.put("port", String.valueOf(instance.getPort()));
    params.put("weight", String.valueOf(instance.getWeight()));
    params.put("enable", String.valueOf(instance.isEnabled()));
    params.put("healthy", String.valueOf(instance.isHealthy()));
    params.put("ephemeral", String.valueOf(instance.isEphemeral()));
    params.put("metadata", JacksonUtils.toJson(instance.getMetadata()));
    
    reqApi(UtilAndComs.nacosUrlInstance, params, HttpMethod.POST);
}

最后会调用到callSever方法,通过http请求将服务信息写到Nacos对应节点:

public String callServer(String api, Map<String, String> params, Map<String, String> body, String curServer,
        String method) throws NacosException {
    long start = System.currentTimeMillis();
    long end = 0;
    injectSecurityInfo(params);
    Header header = builderHeader();
    String url;
    if (curServer.startsWith(UtilAndComs.HTTPS) || curServer.startsWith(UtilAndComs.HTTP)) {
        url = curServer + api;
    } else {
        if (!curServer.contains(UtilAndComs.SERVER_ADDR_IP_SPLITER)) {
            curServer = curServer + UtilAndComs.SERVER_ADDR_IP_SPLITER + serverPort;
        }
        url = NamingHttpClientManager.getInstance().getPrefix() + curServer + api;
    }
    try {
        HttpRestResult<String> restResult = nacosRestTemplate
                .exchangeForm(url, header, Query.newInstance().initParams(params), body, method, String.class);
        end = System.currentTimeMillis();
        if (restResult.ok()) {
            return restResult.getData();
        }
        if (HttpStatus.SC_NOT_MODIFIED == restResult.getCode()) {
            return StringUtils.EMPTY;
        }
        throw new NacosException(restResult.getCode(), restResult.getMessage());
    } catch (Exception e) {
        throw new NacosException(NacosException.SERVER_ERROR, e);
    }
}

到这里服务暴露和服务注册都完成了,看一下整个流程:

三、总结

本篇文章分析了dubbo服务的暴露和注册,里边涉及了spring的扩展能力、dubbo自定义SPI实现、分层和模块化设计等众多内容,希望对大家平时dubbo的使用和理解有所帮助,同时作为文末彩蛋,感兴趣的读者可以关注下一下几个知识点或问题:

  1. dubbo的injvm是怎么一回事,并且是如何实现的？
  2. 对于使用dubbo注解@Service或者@DubboService标注的类,应用启动后能否像spring管理的组件一样注入和使用？
  3. 被@Service或者@DubboService标注的类,会被解析定义成ServiceBean,而ServiceBean不是FactoryBean,如何保证上下文管理差异化？
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Dubbo服务暴露注册原理
dubbo是java领域应用最广泛的rpc框架之一,服务端启动时把服务注册到注册中心,客户端启动时向注册中心订阅服务,然后通过客户端的负载和路由机器选择对应的服...
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