今天,我将真正看到dubo内部的实现过程。在看dubo的源代码之前,我将大致阅读dubo的用户指南和开发指南,以便更容易看到dubo源代码。我们可以从用户指南和开发指南中找到相应的切入点。今天,我们将介绍dubo对bean的初步分析过程: 解析服务 基于dubo.jar中的META-INF/spring.handlers配置,Spring在遇到dubbo名称空间时,会回调dubonamespacehandler。 所有dubbo标签均由dubbobeandefinitionParser统一分析,XML标签根据一对一属性映射分析为bean对象。 Serviceconfig.export()或者Referenceconfigggigg.get()初始化时,将Bean对象转换为URL格式,将所有Bean属性转换为URL参数。 然后将URL传输到基于扩展点的Adaptive机制的Protocol扩展点,并根据URL协议头暴露或引用不同协议的服务。 dubbo服务的曝光调用是:ServiceConfig.export()代码如下:
com.alibaba.dubbo.config.ServiceConfig#export //暴露服务 public synchronized void export() { if (provider != null) { if (export == null) { export = provider.getExport(); } if (delay == null) { delay = provider.getDelay(); } } if (export != null && ! export.booleanValue()) { return; } if (delay != null && delay > 0) { Thread thread = new Thread(new Runnable() { public void run() { try { Thread.sleep(delay); } catch (Throwable e) { } doExport(); } }); thread.setDaemon(true); thread.setName("DelayExportServiceThread"); thread.start(); } else { doExport(); } }
查看export调用链时,这种方法可以在两个地方调用: 1、com.alibaba.dubbo.config.spring.AnnotationBean#postProcessAfterInitialization:当注释方法暴露时 2、com.alibaba.dubbo.config.spring.ServiceBean#afterPropertiesSet:当spring配置文件暴露时, AnnnotationBean类继承关系 public class AnnotationBean extends AbstractConfig implements DisposableBean, BeanFactoryPostProcessor, BeanPostProcessor, ApplicationContextAware { AnnnotationBean实现了spring 在spring扫描完注解类后,bean与context相关的界面,并对完时调用进行分析 export()暴露服务的方法 ServiceBean public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener, BeanNameAware { 在spring初始化分析bean中完成,主要是对spring标签的分析,bean的定义,bean的属性分析设值完成后 进行 export() 因为dubbo是自己定制的标签,所以对bean的分析是 export 以前最重要的部分,今天先不看服务的暴露,先看dubo对服务的分析,重要的两类:
com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler com.alibaba.dubbo.config.spring.schema.DubboBeanDefinitionParser#parse 以下是DubbonamespaceHandler代码,加上我的注释(我自己的理解) public class DubboNamespaceHandler extends NamespaceHandlerSupport { static { /** * 检索是否有重复命名空间处理器 */ Version.checkDuplicate(DubboNamespaceHandler.class); } public void init() { /** * 注册bean,真正的负分析是DubobeandefinitionParser * dubobeandefinitionParser将分析所有属性,并将属性值放入beandefinition */ 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)); } } 所有的分析工作都在那里 DubboBeanDefinitionParser 中 /** * 分析dubo自定义标签,将属性值设置为Beandefinition,此时bean还没有创建 * @param element * @param parserContext * @param beanClass * @param required * @return */ @SuppressWarnings("unchecked") private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) { RootBeanDefinition beanDefinition = new RootBeanDefinition(); beanDefinition.setBeanClass(beanClass); //设置懒加载为false,表示立即加载,spring启动时,立即进行实例化 //如果设置为true,则需要在第一次通过getbean向容器索取bean时进行实例化,spring 可以在bean的配置中配置 ////这里会设置懒加载到false,但也可以得出推断:dubo标签创建的bean是单例bean(singleton bean) //因为lazy-init的设置只针对singleton bean有效,对原型bean(prototype无效) beanDefinition.setLazyInit(false); String id = element.getAttribute("id"); ///如果没有设置beanid if ((id == null || id.length() == 0) && required) { String generatedBeanName = element.getAttribute("name"); //name没有配置 if (generatedBeanName == null || generatedBeanName.length() == 0) { //如果是ProtocolConfig类型,bean 默认name dubbo,其他interface值为配置 if (ProtocolConfig.class.equals(beanClass)) { generatedBeanName = "dubbo"; } else { generatedBeanName = element.getAttribute("interface"); } } /* * 假如还是null 那么取 beanClass 的名字,beanClass 其实就是要分析的类型 * 如:com.alibaba.dubbo.config.ApplicationConfig */ if (generatedBeanName == null || generatedBeanName.length() == 0) { generatedBeanName = beanClass.getName(); } //如果id没有设置,那么 id = generatedBeanName,如果是ProtocolConfig类型,自然是 dubbo id = generatedBeanName; int counter = 2; /* * 因为spring的beang id不能重复,但有些标签可能会配置多个标签,如:<dubbo:registry * 所以 id 在后面添加数字 2、3、4 区分 */ while(parserContext.getRegistry().containsBeanDefinition(id)) { id = generatedBeanName + (counter ++); } } if (id != null && id.length() > 0) { //检查是否有 bean id 相同的 if (parserContext.getRegistry().containsBeanDefinition(id)) { throw new IllegalStateException("Duplicate spring bean id " + id); } /* * 注册 bean 定义 * org.springframework.beans.factory.support.DefaultListableBeanFactory#registerBeanDefinition * 会按照 id 也就是说,beannname做一些检查,判断bean是否重载加载等 * 其实跟着代码走 bean 注册也是放进去的 ConcurrentHashMap 里 * beannnname就是这里 id 会放到 list 里 */ parserContext.getRegistry().registerBeanDefinition(id, beanDefinition); ///给bean添加属性值 beanDefinition.getPropertyValues().addPropertyValue("id", id); } if (ProtocolConfig.class.equals(beanClass)) { for (String name : parserContext.getRegistry().getBeanDefinitionNames()) { BeanDefinition definition = parserContext.getRegistry().getBeanDefinition(name); PropertyValue property = definition.getPropertyValues().getPropertyValue("protocol"); if (property != null) { Object value = property.getValue(); if (value instanceof ProtocolConfig && id.equals(((ProtocolConfig) value).getName())) { definition.getPropertyValues().addPropertyValue("protocol", new RuntimeBeanReference(id)); } } } } else if (ServiceBean.class.equals(beanClass)) { //解析<dubbo:service String className = element.getAttribute("class");//获取类全名 if(className != null && className.length() > 0) { RootBeanDefinition classDefinition = new RootBeanDefinition(); //通过反射获取类 classDefinition.setBeanClass(ReflectUtils.forName(className)); classDefinition.setLazyInit(false); /* 分析子节点,有些配置可能是: <dubbo:service interface="com.alihealth.dubbo.api.drugInfo.service.DemoService" executes="10" > <property ref="demoService" name="ref"></property> <property value="1.0.0" name="version"></property> </dubbo:service> */ parseProperties(element.getChildNodes(), classDefinition); /* 直接设置ref 接口名 + Impl 的bean ? 如:com.alihealth.dubbo.api.drugInfo.service.DemoService + Impl 为什么bean? 那<dubbo:service中定义的service ref 属性有啥用 */ beanDefinition.getPropertyValues().addPropertyValue("ref", new BeanDefinitionHolder(classDefinition, id + "Impl")); } } else if (ProviderConfig.class.equals(beanClass)) { /* <dubbo:provider 为缺省配置 ,所以在分析的时候,如果<dubbo:service有些值没有配置,那么会用<dubbo:provider值填充 */ parseNested(element, parserContext, ServiceBean.class, true, "service", "provider", id, beanDefinition); } else if (ConsumerConfig.class.equals(beanClass)) { /* * 同上 */ parseNested(element, parserContext, ReferenceBean.class, false, "reference", "consumer", id, beanDefinition); } Set<String> props = new HashSet<String>(); ManagedMap parameters = null; for (Method setter : beanClass.getMethods()) { String name = setter.getName(); ////注入model时,比如ServiceConfig,方法必须从set开始,而且参数只能是1 if (name.length() > 3 && name.startsWith("set") && Modifier.isPublic(setter.getModifiers()) && setter.getParameterTypes().length == 1) { //方法参数类型,因为参数只能是1,直接取[0] Class<?> type = setter.getParameterTypes()[0]; ///根据set方法名获取属性值,如:setListener 获得的属性为:listener String property = StringUtils.camelToSplitName(name.substring(3, 4).toLowerCase() + name.substring(4), "-"); props.add(property); Method getter = null; try { getter = beanClass.getMethod("get" + name.substring(3), new Class<?>[0]); } catch (NoSuchMethodException e) { try { getter = beanClass.getMethod("is" + name.substring(3), new Class<?>[0]); } catch (NoSuchMethodException e2) { } } if (getter == null || !>[0]); } catch (NoSuchMethodException e2) { } } if (getter == null || ! Modifier.isPublic(getter.getModifiers()) || ! type.equals(getter.getReturnType())) { continue; } if ("parameters".equals(property)) { /* * 如果属性为 parameters,例如Protocolconfig中的setParametersers(Map<String, String> parameters) * 然后去子节点获取 <dubbo:parameter * <dubbo:protocol name="dubbo" host="127.0.0.1" port="9998" accepts="1000" > <dubbo:parameter key="adsf" value="adf" /> <dubbo:parameter key="errer" value="aerdf" /> </dubbo:protocol> */ parameters = parseParameters(element.getChildNodes(), beanDefinition); } else if ("methods".equals(property)) { /* 解析 <dubbo:method 并设置 methods 值 --serviceconfig */ parseMethods(id, element.getChildNodes(), beanDefinition, parserContext); } else if ("arguments".equals(property)) { /* 同上 ,解析<dubbo:argument --- MethodConfig */ parseArguments(id, element.getChildNodes(), beanDefinition, parserContext); } else { String value = element.getAttribute(property); if (value != null) { value = value.trim(); if (value.length() > 0) { ///不在任何注册中心发布 registry = "N/A" if ("registry".equals(property) && RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(value)) { RegistryConfig registryConfig = new RegistryConfig(); registryConfig.setAddress(RegistryConfig.NO_AVAILABLE); beanDefinition.getPropertyValues().addPropertyValue(property, registryConfig); } else if ("registry".equals(property) && value.indexOf(',') != -1) { //多注册中心使用 , 号分隔 parseMultiRef("registries", value, beanDefinition, parserContext); } else if ("provider".equals(property) && value.indexOf(',') != -1) { parseMultiRef("providers", value, beanDefinition, parserContext); } else if ("protocol".equals(property) && value.indexOf(',') != -1) { //同上 多协议暴露 parseMultiRef("protocols", value, beanDefinition, parserContext); } else { Object reference; if (isPrimitive(type)) 如果参数类型为{// java 的基本类型 if ("async".equals(property) && "false".equals(value) || "timeout".equals(property) && "0".equals(value) || "delay".equals(property) && "0".equals(value) || "version".equals(property) && "0.0.0".equals(value) || "stat".equals(property) && "-1".equals(value) || "reliable".equals(property) && "false".equals(value)) { /* 与旧版xsd中的default值兼容,上述配置值在xsd中有配置defalt值 <xsd:attribute name="version" type="xsd:string" use="optional" default="0.0.0"> */ value = null; } reference = value; } else if ("protocol".equals(property) //如果属性是 protocol 所以要判断protocol对应的扩展点配置是否有 && ExtensionLoader.getExtensionLoader(Protocol.class).hasExtension(value) ///检查当前使用的协议是否已分析 这里可以分析一下<dubbo:protocol name="dubbo" && (! parserContext.getRegistry().containsBeanDefinition(value) || ! ProtocolConfig.class.getName().equals(parserContext.getRegistry().getBeanDefinition(value).getBeanClassName()))) { if ("dubbo:provider".equals(element.getTagName())) { logger.warn("Recommended replace <dubbo:provider protocol=\"" + value + "\" ... /> to <dubbo:protocol name=\"" + value + "\" ... />"); } // 与旧版配置兼容 ProtocolConfig protocol = new ProtocolConfig(); protocol.setName(value); reference = protocol; } else if ("monitor".equals(property) //同上 && (! parserContext.getRegistry().containsBeanDefinition(value) || ! MonitorConfig.class.getName().equals(parserContext.getRegistry().getBeanDefinition(value).getBeanClassName()))) { // 与旧版配置兼容 reference = convertMonitor(value); } else if ("onreturn".equals(property)) { ///回调方法 类似于onsucccessss int index = value.lastIndexOf("."); // bean的名字 String returnRef = value.substring(0, index); String returnMethod = value.substring(index + 1); reference = new RuntimeBeanReference(returnRef); beanDefinition.getPropertyValues().addPropertyValue("onreturnMethod", returnMethod); } else if ("onthrow".equals(property)) { //回调 执行异常的方法 ,类似 onError int index = value.lastIndexOf("."); String throwRef = value.substring(0, index); String throwMethod = value.substring(index + 1); reference = new RuntimeBeanReference(throwRef); beanDefinition.getPropertyValues().addPropertyValue("onthrowMethod", throwMethod); } else { if ("ref".equals(property) && parserContext.getRegistry().containsBeanDefinition(value)) { BeanDefinition refBean = parserContext.getRegistry().getBeanDefinition(value); /* 必须是单例bean(singleton),原型bean(prototype)不,sevice初始化一次,spring容器中只有一个 实例 是否与dubbo的权力等有关,如果是原型bean,那么服务就会变得有状态。 */ if (! refBean.isSingleton()) { throw new IllegalStateException("The exported service ref " + value + " must be singleton! Please set the " + value + " bean scope to singleton, eg: <bean id=\"" + value+ "\" scope=\"singleton\" ...>"); } } reference = new RuntimeBeanReference(value); } /* 设置属性,beann值是另一个相关的 RuntimeBeanReference 当beanfactory作为另一个bean的引用时,固定占位符类作为属性值对象,在运行过程中进行分析 */ beanDefinition.getPropertyValues().addPropertyValue(property, reference); } } } } } } NamedNodeMap attributes = element.getAttributes(); int len = attributes.getLength(); for (int i = 0; i < len; i++) { Node node = attributes.item(i); String name = node.getLocalName(); ///通过上述分析,如果还有一些属性没有被分析 if (! props.contains(name)) { if (parameters == null) { parameters = new ManagedMap(); } String value = node.getNodeValue(); parameters.put(name, new TypedStringValue(value, String.class)); } } if (parameters != null) { beanDefinition.getPropertyValues().addPropertyValue("parameters", parameters); } return beanDefinition; } private static final Pattern GROUP_AND_VERION = Pattern.compile""""-.0-9_a-zA-Z]+(\\:[\\-.0-9_a-zA-Z]+)?$"); protected static MonitorConfig convertMonitor(String monitor) { if (monitor == null || monitor.length() == 0) { return null; } if (GROUP_AND_VERION.matcher(monitor).matches()) { String group; String version; int i = monitor.indexOf(':'); if (i > 0) { group = monitor.substring(0, i); version = monitor.substring(i + 1); } else { group = monitor; version = null; } MonitorConfig monitorConfig = new MonitorConfig(); monitorConfig.setGroup(group); monitorConfig.setVersion(version); return monitorConfig; } return null; } private static boolean isPrimitive(Class<?> cls) { return cls.isPrimitive() || cls == Boolean.class || cls == Byte.class || cls == Character.class || cls == Short.class || cls == Integer.class || cls == Long.class || cls == Float.class || cls == Double.class || cls == String.class || cls == Date.class || cls == Class.class; } @SuppressWarnings("unchecked") private static void parseMultiRef(String property, String value, RootBeanDefinition beanDefinition, ParserContext parserContext) { //解析 registries 、providers、protocols 支持多引用 String[] values = value.split("\\s*[,]+\\s*"); ManagedList list = null; for (int i = 0; i < values.length; i++) { String v = values[i]; if (v != null && v.length() > 0) { if (list == null) { list = new ManagedList(); } list.add(new RuntimeBeanReference(v)); } } beanDefinition.getPropertyValues().addPropertyValue(property, list); } private static void parseNested(Element element, ParserContext parserContext, Class<?> beanClass, boolean required, String tag, String property, String ref, BeanDefinition beanDefinition) { NodeList nodeList = element.getChildNodes(); if (nodeList != null && nodeList.getLength() > 0) { boolean first = true; for (int i = 0; i < nodeList.getLength(); i++) { Node node = nodeList.item(i); if (node instanceof Element) { if (tag.equals(node.getNodeName()) || tag.equals(node.getLocalName())) { if (first) { first = false; String isDefault = element.getAttribute("default"); /* 如果 <dubbo:provider default开关没有配置标签,然后直接设置 default = "false" 这样做的目的是为了让 <dubbo:provider中的配置只是 <dubbo:service 或 <dubbo:reference的默认或缺乏配置 */ if (isDefault == null || isDefault.length() == 0) { beanDefinition.getPropertyValues().addPropertyValue("default", "false"); } } BeanDefinition subDefinition = parse((Element) node, parserContext, beanClass, required); if (subDefinition != null && ref != null && ref.length() > 0) { subDefinition.getPropertyValues().addPropertyValue(property, new RuntimeBeanReference(ref)); } } } } } } private static void parseProperties(NodeList nodeList, RootBeanDefinition beanDefinition) { if (nodeList != null && nodeList.getLength() > 0) { for (int i = 0; i < nodeList.getLength(); i++) { Node node = nodeList.item(i); if (node instanceof Element) { //如果是 <property 元素 if ("property".equals(node.getNodeName()) || "property".equals(node.getLocalName())) { String name = ((Element) node).getAttribute("name"); if (name != null && name.length() > 0) { String value = ((Element) node).getAttribute("value"); //获取 ref String ref = ((Element) node).getAttribute("ref"); if (value != null && value.length() > 0) { beanDefinition.getPropertyValues().addPropertyValue(name, value); } else if (ref != null && ref.length() > 0) { beanDefinition.getPropertyValues().addPropertyValue(name, new RuntimeBeanReference(ref)); } else { /* 只支持两种property设置方法: <property ref="" name=""> <property value="" name=""> */ throw new UnsupportedOperationException("Unsupported <property name=\"" + name + "\"> sub tag, Only supported <property name=\"" + name + "\" ref=\"...\" /> or <property name=\"" + name + "\" value=\"...\" />"); } } } } } } } @SuppressWarnings("unchecked") private static ManagedMap parseParameters(NodeList nodeList, RootBeanDefinition beanDefinition) { if (nodeList != null && nodeList.getLength() > 0) { ManagedMap parameters = null; for (int i = 0; i < nodeList.getLength(); i++) { Node node = nodeList.item(i); if (node instanceof Element) { //解析 <dubbo:parameter if ("parameter".equals(node.getNodeName()) || "parameter".equals(node.getLocalName())) { if (parameters == null) { parameters = new ManagedMap(); } String key = ((Element) node).getAttribute("key"); String value = ((Element) node).getAttribute("value"); boolean hide = "true".equals(((Element) node).getAttribute("hide")); if (hide) { key = Constants.HIDE_KEY_PREFIX + key; } //添加参数,String 类型 parameters.put(key, new TypedStringValue(value, String.class)); } } } return parameters; } return null; } @SuppressWarnings("unchecked") private static void parseMethods(String id, NodeList nodeList, RootBeanDefinition beanDefinition, ParserContext parserContext) { if (nodeList != null && nodeList.getLength() > 0) { ManagedList methods = null; for (int i = 0; i < nodeList.getLength(); i++) { Node node = nodeList.item(i); if (node instanceof Element) { Element element = (Element) node; //<dubbo:method if ("method".equals(node.getNodeName()) || "method".equals(node.getLocalName())) { String methodName = element.getAttribute("name"); if (methodName == null || methodName.length() == 0) { throw new IllegalStateException("<dubbo:method> name attribute == null"); } if (methods == null) { methods = new ManagedList(); } //解析 <dubbo:method MethodConfig BeanDefinition methodBeanDefinition = parse(((Element) node), parserContext, MethodConfig.class, false); String name = id + "." + methodName; BeanDefinitionHolder methodBeanDefinitionHolder = new BeanDefinitionHolder( methodBeanDefinition, name); methods.add(methodBeanDefinitionHolder); } } } if (methods != null) { beanDefinition.getPropertyValues().addPropertyValue("methods", methods); } } }
分析的最终目的是返回 RootBeanDefinition 对象,Rootbeandefinition包含了对bean进行分析的所有信息,注意bean分析后,其实只是spring将其转化为spring内部的抽象数据对象结构,bean的创建(实例化)是第一次调用 getBean 时创建的。以上是dubo对配置文件和服务定义的分析过程。以上是dubbo对配置文件和服务定义的分析过程。然后写下dubo服务的曝光。 关注我获取视频 [img]http://dl2.iteye.com/upload/attachment/0129/523/9485a98f-3715-3b4-a953-a8e2498.jpg[/img]
![](/images/780-200-2.jpg)