Dubbo-服务提供者初始化
服务提供者初始化过程，即ServiceBean 初始化过程
一、解析配置文件
spring在解析配置文件的过程中，会找到dubbo 命名空间对应的handler，DubboNamespaceHandler
public class DubboNamespaceHandler extends NamespaceHandlerSupport { static { Version.checkDuplicate(DubboNamespaceHandler.class); } public void init() { registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true)); registerBeanDefinitionParser("module", new DubboBeanDefinitionParser(ModuleConfig.class, true)); registerBeanDefinitionParser("registry", new DubboBeanDefinitionParser(RegistryConfig.class, true)); registerBeanDefinitionParser("monitor", new DubboBeanDefinitionParser(MonitorConfig.class, true)); registerBeanDefinitionParser("provider", new DubboBeanDefinitionParser(ProviderConfig.class, true)); registerBeanDefinitionParser("consumer", new DubboBeanDefinitionParser(ConsumerConfig.class, true)); registerBeanDefinitionParser("protocol", new DubboBeanDefinitionParser(ProtocolConfig.class, true)); registerBeanDefinitionParser("service", new DubboBeanDefinitionParser(ServiceBean.class, true)); registerBeanDefinitionParser("reference", new DubboBeanDefinitionParser(ReferenceBean.class, false)); registerBeanDefinitionParser("annotation", new DubboBeanDefinitionParser(AnnotationBean.class, true)); } }
启动大致流程
流程如下
- spring容器启动
- ServiceBean初始化
- 事件发布，执行onApplicationEvent，开始执行ServiceBean暴露export操作
- 启动NettyServer
- 注册中心服务暴露export
二、ServiceBean执行export
当Spring容器处理完<dubbo:service>标签后，会在Spring容器中生成一个ServiceBean ，服务的发布也会在ServiceBean中完成。不妨看一下ServiceBean的定义
public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener, BeanNameAware { }
而在Spring初始化完成Bean的组装，会调用InitializingBean的afterPropertiesSet方法，在Spring容器加载完成，会接收到事件ContextRefreshedEvent，调用ApplicationListener的onApplicationEvent方法。
public void afterPropertiesSet() throws Exception { // if (!isDelay()) { // 暴露服务 export(); } }
ServiceBean 实现了ApplicationListener接口，实现onApplicationEvent方法，该方法在spring容器启动完成后“自动”执行
public void onApplicationEvent(ApplicationEvent event) {
if (ContextRefreshedEvent.class.getName().equals(event.getClass().getName())) {
if (isDelay() && !isExported() && !isUnexported()) {
if (logger.isInfoEnabled()) {
logger.info("The service ready on spring started. service: " + getInterface());
}
//
export();
}
}
}
public synchronized void export() {
// 延时暴露
if (delay != null && delay > 0) {
delayExportExecutor.schedule(new Runnable() {
public void run() {
// 暴露服务
doExport();
}
}, delay, TimeUnit.MILLISECONDS);
} else {
// 直接暴露服务
doExport();
}
}
protected synchronized void doExport() { // checkApplication(); checkRegistry(); checkProtocol(); appendProperties(this); checkStubAndMock(interfaceClass); if (path == null || path.length() == 0) { path = interfaceName; } doExportUrls(); }
private void doExportUrls() { List<URL> registryURLs = loadRegistries(true); for (ProtocolConfig protocolConfig : protocols) { doExportUrlsFor1Protocol(protocolConfig, registryURLs); } }
private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) { //如果不是remote，则暴露本地服务 if (!Constants.SCOPE_REMOTE.toString().equalsIgnoreCase(scope)) { exportLocal(url); } // 如果配置不是local则暴露为远程服务 if (!Constants.SCOPE_LOCAL.toString().equalsIgnoreCase(scope)) { // 如果注册中心地址不为null if (registryURLs != null && registryURLs.size() > 0) { for (URL registryURL : registryURLs) { url = url.addParameterIfAbsent("dynamic", registryURL.getParameter("dynamic")); // 忽略不相干的代码 ... // 通过代理工厂将ref对象转化成invoker对象 Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString())); // 代理invoker对象 DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this); // 暴露服务 Exporter<?> exporter = protocol.export(wrapperInvoker); // 一个服务可能有多个提供者，保存在一起 exporters.add(exporter); } } else { Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url); DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this); Exporter<?> exporter = protocol.export(wrapperInvoker); exporters.add(exporter); } } }
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException { URL url = invoker.getUrl(); //忽略若干代码 //打开服务 openServer(url); optimizeSerialization(url); return exporter; }
private void openServer(URL url) { String key = url.getAddress(); boolean isServer = url.getParameter(Constants.IS_SERVER_KEY, true); //是否server端 if (isServer) { ExchangeServer server = serverMap.get(key); if (server == null) { //如果服务不存在，创建服务 serverMap.put(key, createServer(url)); } else { server.reset(url); } } }
private ExchangeServer createServer(URL url) { //忽略若干代码 ExchangeServer server; try { server = Exchangers.bind(url, requestHandler); } catch (RemotingException e) { throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e); } return server; }
生成的Adpative
import com.alibaba.dubbo.common.extension.ExtensionLoader; public class Protocol$Adpative implements com.alibaba.dubbo.rpc.Protocol { public void destroy() { // 抛出异常，省略 } public int getDefaultPort() { // 抛出异常，省略 } // export public com.alibaba.dubbo.rpc.Exporter export(com.alibaba.dubbo.rpc.Invoker arg0) throws RpcException { if (arg0 == null) throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument == null"); if (arg0.getUrl() == null) throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument getUrl() == null"); com.alibaba.dubbo.common.URL url = arg0.getUrl(); String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() ); if(extName == null) throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(" + url.toString() + ") use keys([protocol])"); Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName); return extension.export(arg0); } public Invoker refer(java.lang.Class arg0, com.alibaba.dubbo.common.URL arg1) throws RpcException { if (arg1 == null) throw new IllegalArgumentException("url == null"); com.alibaba.dubbo.common.URL url = arg1; String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() ); if(extName == null) throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(" + url.toString() + ") use keys([protocol])"); Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName); return extension.refer(arg0, arg1); } }
