Dubbo ServiceBean启动源码解析

蔚落 2022-05-24 10:37 266阅读 0赞

前言

spring2.5以后，spring支持自定义schema扩展xml配置。具体的spring schema细节，本文就不多说了。这篇文章就拿provider为例，介绍dubbo是如何启动服务的。

正文

首先，再把HelloWolrd例子中的 provider.xml的源码放上来

Xml代码 收藏代码

  1. <?**xml version=”1.0” encoding=”UTF-8”?>**
  2. <**beans** xmlns=”http://www.springframework.org/schema/beans“
  3. xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance“
  4. xmlns:dubbo=”http://code.alibabatech.com/schema/dubbo“
  5. xsi:schemaLocation=”http://www.springframework.org/schema/beans
  6. http://www.springframework.org/schema/beans/spring-beans.xsd
  7. http://code.alibabatech.com/schema/dubbo
  8. http://code.alibabatech.com/schema/dubbo/dubbo.xsd
  9. “>
  10. <**dubbo:application name=”hello-world-app” />**
  11. <**dubbo:registry protocol=”zookeeper” address=”10.125.195.174:2181” />**
  12. <**dubbo:protocol name=”dubbo” port=”20880” />**
  13. <**dubbo:service** interface=”demo.service.DemoService”
  14. ref=”demoService” />
  15. <**bean id=”demoService” class=”demo.service.DemoServiceImpl” />**

  16. </**beans**>

    对应的自定义schema文件，就不解释了。直接在dubbo-{version}.jar 中 META-INF目录下找到对应的handler配置

spring.handlers 写道

http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler

可以看到，对应的handler是 DubboNamespaceHandler。对应的源码如下

Java代码 收藏代码

  1. public class DubboNamespaceHandler extends NamespaceHandlerSupport {
  3. static {
  4. Version.checkDuplicate(DubboNamespaceHandler.class);
  5. }
  7. public void init() {
  8. registerBeanDefinitionParser(“application”, new DubboBeanDefinitionParser(ApplicationConfig.class, true));
  9. registerBeanDefinitionParser(“module”, new DubboBeanDefinitionParser(ModuleConfig.class, true));
  10. registerBeanDefinitionParser(“registry”, new DubboBeanDefinitionParser(RegistryConfig.class, true));
  11. registerBeanDefinitionParser(“monitor”, new DubboBeanDefinitionParser(MonitorConfig.class, true));
  12. registerBeanDefinitionParser(“provider”, new DubboBeanDefinitionParser(ProviderConfig.class, true));
  13. registerBeanDefinitionParser(“consumer”, new DubboBeanDefinitionParser(ConsumerConfig.class, true));
  14. registerBeanDefinitionParser(“protocol”, new DubboBeanDefinitionParser(ProtocolConfig.class, true));
  15. registerBeanDefinitionParser(“service”, new DubboBeanDefinitionParser(ServiceBean.class, true));
  16. registerBeanDefinitionParser(“reference”, new DubboBeanDefinitionParser(ReferenceBean.class, false));
  17. registerBeanDefinitionParser(“annotation”, new DubboBeanDefinitionParser(AnnotationBean.class, true));
  18. }

  20. }

    从这里也可以看到，对应的支持的标签其实不多。所有的Parser都封装到了DubboBeanDefinitionParser中。对应的class，就是传入的beanClass。比如application的就是ApplicationConfig。module的就是ModuleConfig。经过Parser的转换，provider.xml大概可以变成如下的样子(具体的解析不多解释了)

Xml代码 收藏代码

  1. <**bean id=”hello-world-app” class=”com.alibaba.dubbo.config.ApplicationConfig”/>**
  2. <**bean id=”registryConfig” class=”com.alibaba.dubbo.config.RegistryConfig”>**
  3. <**property name=”address” value=”10.125.195.174:2181”/>**
  4. <**property name=”protocol” value=”zookeeper”/>**
  5. </**bean**>
  6. <**bean id=”dubbo” class=”com.alibaba.dubbo.config.ProtocolConfig”>**
  7. <**property name=”port” value=”20880”/>**
  8. </**bean**>
  9. <**bean id=”demo.service.DemoService” class=”com.alibaba.dubbo.config.spring.ServiceBean”>**
  10. <**property name=”interface” value=”demo.service.DemoService”/>**
  11. <**property name=”ref” ref=”demoService”/>**
  12. </**bean**>
  13. <**bean id=”demoService” class=”demo.service.DemoServiceImpl” />**

分别看每一个bean的内容。由于篇幅原因，我就不把每个代码放上来了。总结一下就是

写道

ApplicationConfig，RegistryConfig，ProtocolConfig都只是普通的pojo。负责接收数据。真正的处理逻辑在ServiceBean中

看具体的代码

Java代码 收藏代码

  1. public class ServiceBean extends ServiceConfig implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener, BeanNameAware {
  3. private static final long serialVersionUID = 213195494150089726L;
  5. private static transient ApplicationContext SPRING_CONTEXT;
  7. private transient ApplicationContext applicationContext;
  9. private transient String beanName;
  11. private transient boolean supportedApplicationListener;
  13. public ServiceBean() {
  14. super();
  15. }
  17. public ServiceBean(Service service) {
  18. super(service);
  19. }
  21. public static ApplicationContext getSpringContext() {
  22. return SPRING_CONTEXT;
  23. }
  24. //设置对应的applicationConext
  25. public void setApplicationContext(ApplicationContext applicationContext) {
  26. this.applicationContext = applicationContext;
  27. SpringExtensionFactory.addApplicationContext(applicationContext);
  28. if (applicationContext != null) {
  29. SPRING_CONTEXT = applicationContext;
  30. try {
  31. Method method = applicationContext.getClass().getMethod(“addApplicationListener”, new Class<?>[]{ApplicationListener.class}); // 兼容Spring2.0.1
  32. method.invoke(applicationContext, new Object[] { this});
  33. supportedApplicationListener = true;
  34. } catch (Throwable t) {
  35. if (applicationContext instanceof AbstractApplicationContext) {
  36. try {
  37. Method method = AbstractApplicationContext.class.getDeclaredMethod(“addListener”, new Class<?>[]{ApplicationListener.class}); // 兼容Spring2.0.1
  38. if (! method.isAccessible()) {
  39. method.setAccessible(true);
  40. }
  41. method.invoke(applicationContext, new Object[] { this});
  42. supportedApplicationListener = true;
  43. } catch (Throwable t2) {
  44. }
  45. }
  46. }
  47. }
  48. }
  50. public void setBeanName(String name) {
  51. this.beanName = name;
  52. }
  54. public void onApplicationEvent(ApplicationEvent event) {
  55. //如果容器加载完成以后当前的provider还没export，那么调用一次export方法（这个针对那种延迟export的情况）
  56. if (ContextRefreshedEvent.class.getName().equals(event.getClass().getName())) {
  57. if (isDelay() && ! isExported() && ! isUnexported()) {
  58. if (logger.isInfoEnabled()) {
  59. logger.info(“The service ready on spring started. service: “ + getInterface());
  60. }
  61. export();
  62. }
  63. }
  64. }
  65. //是否延迟export
  66. private boolean isDelay() {
  67. Integer delay = getDelay();
  68. ProviderConfig provider = getProvider();
  69. if (delay == null && provider != null) {
  70. delay = provider.getDelay();
  71. }
  72. return supportedApplicationListener && (delay == null || delay.intValue() == -1);
  73. }
  75. @SuppressWarnings({ “unchecked”, “deprecation” })
  76. public void afterPropertiesSet() throws Exception {
  77. //这里的Provider其实就是ProviderConfig对象。如果provider为空，表示spring在创建 当前bean的时候还没有初始化ProtocolConfig bean。这里就是做一个前后顺序保证
  78. if (getProvider() == null) {
  79. Map providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false);
  80. if (providerConfigMap != null && providerConfigMap.size() > 0) {
  81. Map protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
  82. if ((protocolConfigMap == null || protocolConfigMap.size() == 0)
  83. && providerConfigMap.size() > 1) { // 兼容旧版本
  84. List providerConfigs = new ArrayList();
  85. for (ProviderConfig config : providerConfigMap.values()) {
  86. if (config.isDefault() != null && config.isDefault().booleanValue()) {
  87. providerConfigs.add(config);
  88. }
  89. }
  90. if (providerConfigs.size() > 0) {
  91. setProviders(providerConfigs);
  92. }
  93. } else {
  94. ProviderConfig providerConfig = null;
  95. for (ProviderConfig config : providerConfigMap.values()) {
  96. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  97. if (providerConfig != null) {
  98. throw new IllegalStateException(“Duplicate provider configs: “ + providerConfig + “ and “ + config);
  99. }
  100. providerConfig = config;
  101. }
  102. }
  103. if (providerConfig != null) {
  104. setProvider(providerConfig);
  105. }
  106. }
  107. }
  108. }
  109. //这里和上面同样，手动创建ApplicationConfig bean
  110. if (getApplication() == null
  111. && (getProvider() == null || getProvider().getApplication() == null)) {
  112. Map applicationConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ApplicationConfig.class, false, false);
  113. if (applicationConfigMap != null && applicationConfigMap.size() > 0) {
  114. ApplicationConfig applicationConfig = null;
  115. for (ApplicationConfig config : applicationConfigMap.values()) {
  116. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  117. if (applicationConfig != null) {
  118. throw new IllegalStateException(“Duplicate application configs: “ + applicationConfig + “ and “ + config);
  119. }
  120. applicationConfig = config;
  121. }
  122. }
  123. if (applicationConfig != null) {
  124. setApplication(applicationConfig);
  125. }
  126. }
  127. }
  128. //如果没有创建module，则手动创建 module。 在HelloWorld例子中，没有用到module。
  129. if (getModule() == null
  130. && (getProvider() == null || getProvider().getModule() == null)) {
  131. Map moduleConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ModuleConfig.class, false, false);
  132. if (moduleConfigMap != null && moduleConfigMap.size() > 0) {
  133. ModuleConfig moduleConfig = null;
  134. for (ModuleConfig config : moduleConfigMap.values()) {
  135. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  136. if (moduleConfig != null) {
  137. throw new IllegalStateException(“Duplicate module configs: “ + moduleConfig + “ and “ + config);
  138. }
  139. moduleConfig = config;
  140. }
  141. }
  142. if (moduleConfig != null) {
  143. setModule(moduleConfig);
  144. }
  145. }
  146. }
  147. //初始化registiry
  148. if ((getRegistries() == null || getRegistries().size() == 0)
  149. && (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().size() == 0)
  150. && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().size() == 0)) {
  151. Map registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
  152. if (registryConfigMap != null && registryConfigMap.size() > 0) {
  153. List registryConfigs = new ArrayList();
  154. for (RegistryConfig config : registryConfigMap.values()) {
  155. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  156. registryConfigs.add(config);
  157. }
  158. }
  159. if (registryConfigs != null && registryConfigs.size() > 0) {
  160. super.setRegistries(registryConfigs);
  161. }
  162. }
  163. }
  164. //初始化monitor （HelloWorld例子中没有用到）
  165. if (getMonitor() == null
  166. && (getProvider() == null || getProvider().getMonitor() == null)
  167. && (getApplication() == null || getApplication().getMonitor() == null)) {
  168. Map monitorConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MonitorConfig.class, false, false);
  169. if (monitorConfigMap != null && monitorConfigMap.size() > 0) {
  170. MonitorConfig monitorConfig = null;
  171. for (MonitorConfig config : monitorConfigMap.values()) {
  172. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  173. if (monitorConfig != null) {
  174. throw new IllegalStateException(“Duplicate monitor configs: “ + monitorConfig + “ and “ + config);
  175. }
  176. monitorConfig = config;
  177. }
  178. }
  179. if (monitorConfig != null) {
  180. setMonitor(monitorConfig);
  181. }
  182. }
  183. }
  184. //初始化protocol
  185. if ((getProtocols() == null || getProtocols().size() == 0)
  186. && (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().size() == 0)) {
  187. Map protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
  188. if (protocolConfigMap != null && protocolConfigMap.size() > 0) {
  189. List protocolConfigs = new ArrayList();
  190. for (ProtocolConfig config : protocolConfigMap.values()) {
  191. if (config.isDefault() == null || config.isDefault().booleanValue()) {
  192. protocolConfigs.add(config);
  193. }
  194. }
  195. if (protocolConfigs != null && protocolConfigs.size() > 0) {
  196. super.setProtocols(protocolConfigs);
  197. }
  198. }
  199. }
  200. //设置服务名称。
  201. if (getPath() == null || getPath().length() == 0) {
  202. if (beanName != null && beanName.length() > 0
  203. && getInterface() != null && getInterface().length() > 0
  204. && beanName.startsWith(getInterface())) {
  205. setPath(beanName);
  206. }
  207. }
  208. //调用export
  209. if (! isDelay()) {
  210. export();
  211. }
  212. }
  213. //调用unexport
  214. public void destroy() throws Exception {
  215. unexport();
  216. }
  218. }

代码里面已经加了一些注释。虽然很长，逻辑还是很简单的。其中用到了spring的很多特性。非常值得我们学习

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