前一篇springCloud 篇幅较长，看起来比较累。这一篇dubbo源码分析，将拆分3篇来分析。

1.版本

这里源码是从git 上拉下来的，现在注解用的多，这也是一篇分析注解版本的。

2.入口

这是spring 容器启动，回加载ProviderConfiguration.class,这个类的 @EnableDubbo 是dubbo 启动的入口。

2.1 跟进 @EnableDubbo

2.2 跟进 @EnableDubboConfig

这个和springCloud 其他组件引入差不多也是通过@Import 注解引入的

2.3 跟进 DubboConfigConfigurationRegistrar.class

import static com.alibaba.spring.util.AnnotatedBeanDefinitionRegistryUtils.registerBeans;
// 静态方法引入
import static org.apache.dubbo.config.spring.util.DubboBeanUtils.registerCommonBeans;/*** Dubbo {@link AbstractConfig Config} {@link ImportBeanDefinitionRegistrar register}, which order can be configured** @see EnableDubboConfig* @see DubboConfigConfiguration* @see Ordered* @since 2.5.8*///实现了这个ImportBeanDefinitionRegistrar  容器刷线会调用registerBeanDefinitions() // 该方法提供往容器注入的接口
public class DubboConfigConfigurationRegistrar implements ImportBeanDefinitionRegistrar {@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {AnnotationAttributes attributes = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(EnableDubboConfig.class.getName()));boolean multiple = attributes.getBoolean("multiple");// Single Config BindingsregisterBeans(registry, DubboConfigConfiguration.Single.class);if (multiple) { // Since 2.6.6 https://github.com/apache/dubbo/issues/3193// 这个就是具体的往容器注入一个beanDefineregisterBeans(registry, DubboConfigConfiguration.Multiple.class);}// Since 2.7.6// 详细看一下这个借口registerCommonBeans(registry);}
}

2.4 DubboBeanUtils.java ->registerCommonBeans（）

 static void registerCommonBeans(BeanDefinitionRegistry registry) {// 这个是处理@Reference 注解既消费者 所依赖的代理入口// spring 属性注入采用的得是 迭代设计模式会依次加载各个组件来进行属性的注入registerInfrastructureBean(registry, ReferenceAnnotationBeanPostProcessor.BEAN_NAME,ReferenceAnnotationBeanPostProcessor.class);// Since 2.7.4 [Feature] https://github.com/apache/dubbo/issues/5093registerInfrastructureBean(registry, DubboConfigAliasPostProcessor.BEAN_NAME,DubboConfigAliasPostProcessor.class);// Since 2.7.5 Register DubboLifecycleComponentApplicationListener as an infrastructure BeanregisterInfrastructureBean(registry, DubboLifecycleComponentApplicationListener.BEAN_NAME,DubboLifecycleComponentApplicationListener.class);// 这里是 生产者 入口地方 他是spring 的观察者模式 在容器刷新会触发registerInfrastructureBean(registry, DubboBootstrapApplicationListener.BEAN_NAME,DubboBootstrapApplicationListener.class);// Since 2.7.6 Register DubboConfigDefaultPropertyValueBeanPostProcessor as an infrastructure BeanregisterInfrastructureBean(registry, DubboConfigDefaultPropertyValueBeanPostProcessor.BEAN_NAME,DubboConfigDefaultPropertyValueBeanPostProcessor.class);}

2.5 DubboBootstrapApplicationListener.class

spring 容器刷新会触发该事件。

2.6 DubboBootstrapApplicationListener.class->onContextRefreshedEvent（）

2.7 DubboBootstrap.class ->start（）

大概是 先cas 避免重复注册。里面大概有三个方法，initialize() 初始化主键，exportServices() 暴露服务,
以及referServices(); 重点看一下 exportServices()

2.8 DubboBootstrap.class ->exportServices（）

configManager.getServices() 获取需要暴露的服务 ，并且把它放到一个map 中依次遍历，依次暴露。
这里 exportAsync=false,方法会执行到 sc.export()

2.9 ServiceConfig.class->export()

这里大概是 先初始化一个服务信息 比如版本 ，判断是否需要延迟加载等。重点是doExport()；

2.9 ServiceConfig.class ->doExport（）

2.10 ServiceConfig.class ->doExportUrls（）

首先拿到注册中心repository，拿到注册地址registryURLs

protocols 协议 是一个

继续跟进 doExportUrlsFor1Protocol(protocolConfig, registryURLs)

2.11 ServiceConfig.class ->doExportUrlsFor1Protocol（）

private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {String name = protocolConfig.getName();if (StringUtils.isEmpty(name)) {name = DUBBO;}Map<String, String> map = new HashMap<String, String>();map.put(SIDE_KEY, PROVIDER_SIDE);ServiceConfig.appendRuntimeParameters(map);AbstractConfig.appendParameters(map, getMetrics());AbstractConfig.appendParameters(map, getApplication());AbstractConfig.appendParameters(map, getModule());// remove 'default.' prefix for configs from ProviderConfig// appendParameters(map, provider, Constants.DEFAULT_KEY);AbstractConfig.appendParameters(map, provider);AbstractConfig.appendParameters(map, protocolConfig);AbstractConfig.appendParameters(map, this);MetadataReportConfig metadataReportConfig = getMetadataReportConfig();if (metadataReportConfig != null && metadataReportConfig.isValid()) {map.putIfAbsent(METADATA_KEY, REMOTE_METADATA_STORAGE_TYPE);}if (CollectionUtils.isNotEmpty(getMethods())) {for (MethodConfig method : getMethods()) {AbstractConfig.appendParameters(map, method, method.getName());String retryKey = method.getName() + ".retry";if (map.containsKey(retryKey)) {String retryValue = map.remove(retryKey);if ("false".equals(retryValue)) {map.put(method.getName() + ".retries", "0");}}List<ArgumentConfig> arguments = method.getArguments();if (CollectionUtils.isNotEmpty(arguments)) {for (ArgumentConfig argument : arguments) {// convert argument typeif (argument.getType() != null && argument.getType().length() > 0) {Method[] methods = interfaceClass.getMethods();// visit all methodsif (methods.length > 0) {for (int i = 0; i < methods.length; i++) {String methodName = methods[i].getName();// target the method, and get its signatureif (methodName.equals(method.getName())) {Class<?>[] argtypes = methods[i].getParameterTypes();// one callback in the methodif (argument.getIndex() != -1) {if (argtypes[argument.getIndex()].getName().equals(argument.getType())) {AbstractConfig.appendParameters(map, argument, method.getName() + "." + argument.getIndex());} else {throw new IllegalArgumentException("Argument config error : the index attribute and type attribute not match :index :" + argument.getIndex() + ", type:" + argument.getType());}} else {// multiple callbacks in the methodfor (int j = 0; j < argtypes.length; j++) {Class<?> argclazz = argtypes[j];if (argclazz.getName().equals(argument.getType())) {AbstractConfig.appendParameters(map, argument, method.getName() + "." + j);if (argument.getIndex() != -1 && argument.getIndex() != j) {throw new IllegalArgumentException("Argument config error : the index attribute and type attribute not match :index :" + argument.getIndex() + ", type:" + argument.getType());}}}}}}}} else if (argument.getIndex() != -1) {AbstractConfig.appendParameters(map, argument, method.getName() + "." + argument.getIndex());} else {throw new IllegalArgumentException("Argument config must set index or type attribute.eg: <dubbo:argument index='0' .../> or <dubbo:argument type=xxx .../>");}}}} // end of methods for}if (ProtocolUtils.isGeneric(generic)) {map.put(GENERIC_KEY, generic);map.put(METHODS_KEY, ANY_VALUE);} else {String revision = Version.getVersion(interfaceClass, version);if (revision != null && revision.length() > 0) {map.put(REVISION_KEY, revision);}String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();if (methods.length == 0) {logger.warn("No method found in service interface " + interfaceClass.getName());map.put(METHODS_KEY, ANY_VALUE);} else {map.put(METHODS_KEY, StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));}}/*** Here the token value configured by the provider is used to assign the value to ServiceConfig#token*/if(ConfigUtils.isEmpty(token) && provider != null) {token = provider.getToken();}if (!ConfigUtils.isEmpty(token)) {if (ConfigUtils.isDefault(token)) {map.put(TOKEN_KEY, UUID.randomUUID().toString());} else {map.put(TOKEN_KEY, token);}}//init serviceMetadata attachmentsserviceMetadata.getAttachments().putAll(map);// export serviceString host = findConfigedHosts(protocolConfig, registryURLs, map);Integer port = findConfigedPorts(protocolConfig, name, map);URL url = new URL(name, host, port, getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), map);// You can customize Configurator to append extra parametersif (ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).hasExtension(url.getProtocol())) {url = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).getExtension(url.getProtocol()).getConfigurator(url).configure(url);}String scope = url.getParameter(SCOPE_KEY);// don't export when none is configuredif (!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)) {// 本地调用 确保在同一个jvm 进程中 能够调用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 registerif (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());}if (logger.isInfoEnabled()) {if (url.getParameter(REGISTER_KEY, true)) {logger.info("Register dubbo service " + interfaceClass.getName() + " url " + url + " to registry " + registryURL);} else {logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);}}// For providers, this is used to enable custom proxy to generate invokerString proxy = url.getParameter(PROXY_KEY);if (StringUtils.isNotEmpty(proxy)) {registryURL = registryURL.addParameter(PROXY_KEY, proxy);}// 将实现类包装一个invoker 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 {if (logger.isInfoEnabled()) {logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);}Invoker<?> invoker = PROXY_FACTORY.getInvoker(ref, (Class) interfaceClass, url);DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);// 远程调用 包括zookeerper 的注册Exporter<?> exporter = PROTOCOL.export(wrapperInvoker);exporters.add(exporter);}/*** @since 2.7.0* ServiceData Store*/WritableMetadataService metadataService = WritableMetadataService.getExtension(url.getParameter(METADATA_KEY, DEFAULT_METADATA_STORAGE_TYPE));if (metadataService != null) {metadataService.publishServiceDefinition(url);}}}this.urls.add(url);}

接下来我们主要看 exportLocal(url); 和 Exporter<?> exporter = PROTOCOL.export(wrapperInvoker);
其他的代码逻辑还是比较清晰的。

2.11.1 ServiceConfig.class -> exportLocal(url)

将接口包装成一个Exporter 并放到一个list 中。
重点 看一下这个方法。
Exporter<?> exporter = PROTOCOL.export(wrapperInvoker);

这是export调用的堆栈信息，

@SPI("dubbo")
public interface Protocol {/***这里会根据dubbo的spi 生产一个带来类，看了上面的堆栈信息，dubbo 采用javasist 生成一个adaptive的class 经过* 类加载器的变异加载最终生成一个Protocol$Adaptive 对象*/@Adaptive<T> Exporter<T> export(Invoker<T> invoker) throws RpcException;

经过ProtocolListenerWrapper.class->export（）—>ProtocolFilterWrapper.class->export（）
–>RegistryProtocol.class ->export（）

2.11.2 RegistryProtocol.class ->export（）

public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {URL registryUrl = getRegistryUrl(originInvoker);// url to export locallyURL providerUrl = getProviderUrl(originInvoker);// Subscribe the override data// FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call//  the same service. Because the subscribed is cached key with the name of the service, it causes the//  subscription information to cover.final URL overrideSubscribeUrl = getSubscribedOverrideUrl(providerUrl);final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);//export invokerfinal ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);// url to registryfinal Registry registry = getRegistry(originInvoker);final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);// decide if we need to delay publishboolean register = providerUrl.getParameter(REGISTER_KEY, true);if (register) {// 注册register(registryUrl, registeredProviderUrl);}// register stated url on provider modelregisterStatedUrl(registryUrl, registeredProviderUrl, register);// Deprecated! Subscribe to override rules in 2.6.x or before.registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);exporter.setRegisterUrl(registeredProviderUrl);// 订阅 就是zookeeper的watcha事件exporter.setSubscribeUrl(overrideSubscribeUrl);notifyExport(exporter);//Ensure that a new exporter instance is returned every time exportreturn new DestroyableExporter<>(exporter);}

2.11.3 RegistryProtocol.class->register（）

2.11.4 ListenerRegistryWrapper.class ->register（）

2.11.5 FailbackRegistry.class ->register（）

2.11.6 ZookeeperRegistry.class ->doRegister（）

void create(String path, boolean ephemeral); 前者传的是路径，后者是否是临时节点。
这里 toUrlPath(url)为:

/dubbo/org.apache.dubbo.demo.DemoService/providers/dubbo%3A%2F%2F192.168.56.1%3A20880%2Forg.apache.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Ddubbo-demo-annotation-provider%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26interface%3Dorg.apache.dubbo.demo.DemoService%26methods%3DsayHello%2CsayHelloAsync%26pid%3D24544%26release%3D%26side%3Dprovider%26timestamp%3D1594951395200

url.getParameter(DYNAMIC_KEY, true)=true；
小结一下：

生产者 在@EnableDubbo 会注入一个监听器，在容器刷新时候会触发，他会暴露本地和远程服务，同时会创建一个临时节点，同时会订阅watch事件。