dubbo源码——服务提供者的服务暴露过程(一)
原创
一、前言
最近在学习dubbo源码，故写下学习dubbo时的一些心得。。
dubbo源码版本：2.6.1
二、自定义标签
<dubbo:xxx/>标签是Spring的自定义标签，可以查看dubbo.jar包下的META-INF->spring.handlers
//file:spring.handlers
http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler它是通过DubboNamespaceHandler继承Spring提供的NamespaceHandlerSupport来对标签进行解析的
//DubboNamespaceHandler.java
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 AnnotationBeanDefinitionParser());
}
}本篇博客主要讲解的是服务提供者的服务暴露过程，也就是<dubbo:service/>标签，那么我们就只需要关心newDubboBeanDefinitionParser(ServiceBean.class,true)，ServiceBean的实现即可。
三、ServiceBean
先附上一张ServiceBean架构图。可以看到ServiceBean实现了一系列的Spring生命周期接口来完成服务的暴露、注册、销毁等操作。
我们暂不必关心其它接口的实现，我们更关心的是InitializingBean的实现，因为它包含了我们所要研究的服务提供者暴露过程。
哇哦，这代码还真tm长啊，一会还有更长的.....
#1：获取<dubbo:service />的provider属性，如果为空，那么就获取<dubbo:provider/>的实例。(dubbo:provider标签配置的是一些缺省值)
①如果没有配置<dubbo:protocol/>协议，并且，<dubbo:provider/>配置了一个以上，那么会选择provider标签配置了default属性的ProviderConfig
②如果配置了<dubbo:protocol/>协议，如果<dubbo:provider/>配置了一个以上那么会报Duplicate provider configs：异常，否则将会选择一个ProviderConfig。
#2获取application属性，如果属性为空，且provider也为空；或者属性为空，provider中application也为空，那么会获取<dubbo:application/>的实例，如果配置了多个<dubbo:application/>标签，则会抛出异常Duplicate application configs:#3获取module属性，和application一样，如果属性为空，且provider也为空；或者属性为空，provider中module也为空那么会获取<dubbo:module/>的实例，如果配置了多个<dubbo:module/>标签，则会抛出异常Duplicate module configs:#4获取registries属性，如果为空，则获取provider中的registries属性，如果也为空，则获取application中的registries属性，如果还为空，那么就去找<dubbo:registry/>标签的实例，dubbo允许配置多个注册中心，将服务注册在不同的注册中心上。#5获取monitor属性，如果为空，则尝试从provider、application中获取，否则，会获取<dubbo:monitor/>标签的实例，monitor可有可无，不过只能配置一个，存在多个会抛出异常Duplicate monitor configs:#6获取protocol属性，如果为空，则获取provider中protocol属性，如果为空，则会获取<dubbo:protocol/>标签的实例，protocol可配置多个，dubbo允许将服务通过不同协议进行暴露。#7延时暴露，如果delay没有设置，或者delay设置为-1将会启用延时加载。是通过实现ApplicationListener接口在SpringIOC初始化完毕后通知ServiceBean完成服务暴露回调，schedule定时任务(单位毫秒)。来实现的。
private boolean isDelay() {
Integer delay = getDelay();
ProviderConfig provider = getProvider();
if (delay == null && provider != null) {
delay = provider.getDelay();
}
return supportedApplicationListener && (delay == null || delay == -1);
} public void onApplicationEvent(ContextRefreshedEvent event) {
if (isDelay() && !isExported() && !isUnexported()) {
if (logger.isInfoEnabled()) {
logger.info("The service ready on spring started. service: " + getInterface());
}
export();
}
}//ServiceBean->afterPropertiesSet()
@SuppressWarnings({"unchecked", "deprecation"})
public void afterPropertiesSet() throws Exception {
if (getProvider() == null) { #1
Map<String, ProviderConfig> providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false);
if (providerConfigMap != null && providerConfigMap.size() > 0) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if ((protocolConfigMap == null || protocolConfigMap.size() == 0)
&& providerConfigMap.size() > 1) { // backward compatibility
List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>();
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() != null && config.isDefault().booleanValue()) {
providerConfigs.add(config);
}
}
if (!providerConfigs.isEmpty()) {
setProviders(providerConfigs);
}
} else {
ProviderConfig providerConfig = null;
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (providerConfig != null) {
throw new IllegalStateException("Duplicate provider configs: " + providerConfig + " and " + config);
}
providerConfig = config;
}
}
if (providerConfig != null) {
setProvider(providerConfig);
}
}
}
}
if (getApplication() == null #2
&& (getProvider() == null || getProvider().getApplication() == null)) {
Map<String, ApplicationConfig> applicationConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ApplicationConfig.class, false, false);
if (applicationConfigMap != null && applicationConfigMap.size() > 0) {
ApplicationConfig applicationConfig = null;
for (ApplicationConfig config : applicationConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (applicationConfig != null) {
throw new IllegalStateException("Duplicate application configs: " + applicationConfig + " and " + config);
}
applicationConfig = config;
}
}
if (applicationConfig != null) {
setApplication(applicationConfig);
}
}
}
if (getModule() == null #3
&& (getProvider() == null || getProvider().getModule() == null)) {
Map<String, ModuleConfig> moduleConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ModuleConfig.class, false, false);
if (moduleConfigMap != null && moduleConfigMap.size() > 0) {
ModuleConfig moduleConfig = null;
for (ModuleConfig config : moduleConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (moduleConfig != null) {
throw new IllegalStateException("Duplicate module configs: " + moduleConfig + " and " + config);
}
moduleConfig = config;
}
}
if (moduleConfig != null) {
setModule(moduleConfig);
}
}
}
if ((getRegistries() == null || getRegistries().isEmpty()) #4
&& (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().isEmpty())
&& (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().isEmpty())) {
Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
if (registryConfigMap != null && registryConfigMap.size() > 0) {
List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
for (RegistryConfig config : registryConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
registryConfigs.add(config);
}
}
if (registryConfigs != null && !registryConfigs.isEmpty()) {
super.setRegistries(registryConfigs);
}
}
}
if (getMonitor() == null #5
&& (getProvider() == null || getProvider().getMonitor() == null)
&& (getApplication() == null || getApplication().getMonitor() == null)) {
Map<String, MonitorConfig> monitorConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MonitorConfig.class, false, false);
if (monitorConfigMap != null && monitorConfigMap.size() > 0) {
MonitorConfig monitorConfig = null;
for (MonitorConfig config : monitorConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (monitorConfig != null) {
throw new IllegalStateException("Duplicate monitor configs: " + monitorConfig + " and " + config);
}
monitorConfig = config;
}
}
if (monitorConfig != null) {
setMonitor(monitorConfig);
}
}
}
if ((getProtocols() == null || getProtocols().isEmpty()) #6
&& (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().isEmpty())) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if (protocolConfigMap != null && protocolConfigMap.size() > 0) {
List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
for (ProtocolConfig config : protocolConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
protocolConfigs.add(config);
}
}
if (protocolConfigs != null && !protocolConfigs.isEmpty()) {
super.setProtocols(protocolConfigs);
}
}
}
if (getPath() == null || getPath().length() == 0) {
if (beanName != null && beanName.length() > 0
&& getInterface() != null && getInterface().length() > 0
&& beanName.startsWith(getInterface())) {
setPath(beanName);
}
}
if (!isDelay()) { #7
export();
}
}接下来分析export()服务暴露方法
#1#2如果没有配置export属性和delay属性，则从provider中获取。#3如果export属性为false，那么将不暴露服务，直接返回。#4如果delay不为空 且大于0，将定时执行服务暴露任务。否则直接执行。
//ServiceConfig.java
//ServiceCofnig->export()
public synchronized void export() {
if (provider != null) { #1
if (export == null) {
export = provider.getExport();
}
if (delay == null) { #2
delay = provider.getDelay();
}
}
if (export != null && !export) { #3
return;
}
if (delay != null && delay > 0) { #4
delayExportExecutor.schedule(new Runnable() {
public void run() {
doExport();
}
}, delay, TimeUnit.MILLISECONDS);
} else {
doExport();
}
}好吧，doExport()方法依然很长。。。
#1如果服务已经暴露，则直接返回。#2<dubbo:service/>中interface配置为空，则抛出异常。#3从参数，或者系统文件中加载属性配置#4前面都是一些属性的填充，很无聊，直接跳过，如果服务ref为genericService或者其子类，那么将会获取generic属性，默认为true。#5否则为普通的接口，加载接口，然后接口方法检查，引用与接口是否匹配。#6stub属性为true，那么会查找接口的Stub类，Stub可以查看这篇博客https://www.cnblogs.com/hzhuxin/p/8250602.html#7进行一系列的属性检查和填充。#8path默认为接口名称例如:dubbo://127.0.0.1:28080/interfaceName.....
//ServiceConfig.java
//ServiceConfig->doExport()
protected synchronized void doExport() {
if (unexported) {
throw new IllegalStateException("Already unexported!");
}
if (exported) { #1
return;
}
exported = true;
if (interfaceName == null || interfaceName.length() == 0) { #2
throw new IllegalStateException("<dubbo:service interface=\"\" /> interface not allow null!");
}
checkDefault(); #3
if (provider != null) {
if (application == null) {
application = provider.getApplication();
}
if (module == null) {
module = provider.getModule();
}
if (registries == null) {
registries = provider.getRegistries();
}
if (monitor == null) {
monitor = provider.getMonitor();
}
if (protocols == null) {
protocols = provider.getProtocols();
}
}
if (module != null) {
if (registries == null) {
registries = module.getRegistries();
}
if (monitor == null) {
monitor = module.getMonitor();
}
}
if (application != null) {
if (registries == null) {
registries = application.getRegistries();
}
if (monitor == null) {
monitor = application.getMonitor();
}
}
if (ref instanceof GenericService) { #4
interfaceClass = GenericService.class;
if (StringUtils.isEmpty(generic)) {
generic = Boolean.TRUE.toString();
}
} else {
try { #5
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
.getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
checkInterfaceAndMethods(interfaceClass, methods);
checkRef();
generic = Boolean.FALSE.toString();
}
if (local != null) {
if ("true".equals(local)) {
local = interfaceName + "Local";
}
Class<?> localClass;
try {
localClass = ClassHelper.forNameWithThreadContextClassLoader(local);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if (!interfaceClass.isAssignableFrom(localClass)) {
throw new IllegalStateException("The local implementation class " + localClass.getName() + " not implement interface " + interfaceName);
}
}
if (stub != null) { #6
if ("true".equals(stub)) {
stub = interfaceName + "Stub";
}
Class<?> stubClass;
try {
stubClass = ClassHelper.forNameWithThreadContextClassLoader(stub);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if (!interfaceClass.isAssignableFrom(stubClass)) {
throw new IllegalStateException("The stub implementation class " + stubClass.getName() + " not implement interface " + interfaceName);
}
}
checkApplication(); #7
checkRegistry();
checkProtocol();
appendProperties(this);
checkStubAndMock(interfaceClass);
if (path == null || path.length() == 0) { #8
path = interfaceName;
}
doExportUrls();
ProviderModel providerModel = new ProviderModel(getUniqueServiceName(), this, ref);
ApplicationModel.initProviderModel(getUniqueServiceName(), providerModel);
}
锵锵锵，该doExportUrls()方法了，眼睛酸，下篇博客讲！
原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。
原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。
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