Dubbox的源码学习(二)

注册服务

dubbox源码分析

经过上面的源码分析,我们知道了dubbox如何进行配置解析,下面看看如何定义一个服务。

  1. 定义服务:修改 dubbox-first-demo.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
        http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    
        <dubbo:application name="test-services" owner="linxm" organization="workhouse"/>
    
        <dubbo:registry address="zookeeper://127.0.0.1:2181"/>
    
        <dubbo:protocol name="rest" port="8888" contextpath="services" />
        <dubbo:protocol name="dubbo" serialization="kryo" />
        
        <dubbo:service interface="me.helllp.demo.dubboxStudy.api.Hello" ref="helloService"  protocol="dubbo" />
        <bean id="helloService" class="me.helllp.demo.dubboxStudy.api.impl.HelloImpl" />
        
    </beans>

这里注意:我们需要启动zookeeper服务!
在pom.xml中增加zookeeper client的依赖

        <!-- 增加zookeeper客户端 -->
        <dependency>
            <groupId>com.github.sgroschupf</groupId>
            <artifactId>zkclient</artifactId>
        </dependency>
  1. 书写服务接口和实现
    public interface Hello {
        public String showMessage();
    }

    public class HelloImpl implements Hello{
    
        @Override
        public String showMessage() {
            return "显示信息";
        }
    
    }
  1. 我们部署Dubbo Admin来查看一下效果
注册的服务

源码分析

基于上一篇的讨论,我们在解析配置文件的dubbo:service节点的时候,会初始化com.alibaba.dubbo.config.spring.ServiceBean
让我们看看ServiceBean都干了什么,下面是代码节选

public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener, BeanNameAware {

    public void setApplicationContext(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
        SpringExtensionFactory.addApplicationContext(applicationContext);
        if (applicationContext != null) {
            SPRING_CONTEXT = applicationContext;
            try {
                Method method = applicationContext.getClass().getMethod("addApplicationListener", new Class<?>[]{ApplicationListener.class}); // 兼容Spring2.0.1
                method.invoke(applicationContext, new Object[] {this});
                supportedApplicationListener = true;
            } catch (Throwable t) {
                if (applicationContext instanceof AbstractApplicationContext) {
                    try {
                        Method method = AbstractApplicationContext.class.getDeclaredMethod("addListener", new Class<?>[]{ApplicationListener.class}); // 兼容Spring2.0.1
                        if (! method.isAccessible()) {
                            method.setAccessible(true);
                        }
                        method.invoke(applicationContext, new Object[] {this});
                        supportedApplicationListener = true;
                    } catch (Throwable t2) {
                    }
                }
            }
        }
    }

    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();
            }
        }
    }
    
}
  1. ServiceBean实现了ApplicationContextAware接口,在初始化的时候会这些接口方法setApplicationContext
  2. setApplicationContext方法中通过反射执行springContext的addApplicationListener方法,将serviceBean作为参数,加入监听队列中(ServiceBean同时还实现了ApplicationListener接口)。
  3. spring容器初始化过程中会向所有的ApplicationListener接口实现发生触发消息,onApplicationEvent方法会执行
  4. onApplicationEvent方法中主要执行父类ServiceConfig的export方法。
  5. export方法主要执行ServiceConfig的doExport方法,这个方法中才是注册服务的真正代码。

doExport方法分析

主要的调用关系

  • doExportUrls()
  • doExportUrls()
  • doExportUrlsFor1Protocol() 注册的逻辑

下面我们看看doExportUrlsFor1Protocol()方法的主要逻辑

        // 导出服务
        String contextPath = protocolConfig.getContextpath();
        if ((contextPath == null || contextPath.length() == 0) && provider != null) {
            contextPath = provider.getContextpath();
        }
        URL url = new URL(name, host, port, (contextPath == null || contextPath.length() == 0 ? "" : contextPath + "/") + path, map);

        if (ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
                .hasExtension(url.getProtocol())) {
            url = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
                    .getExtension(url.getProtocol()).getConfigurator(url).configure(url);
        }

        String scope = url.getParameter(Constants.SCOPE_KEY);
        //配置为none不暴露
        if (! Constants.SCOPE_NONE.toString().equalsIgnoreCase(scope)) {

            //配置不是remote的情况下做本地暴露 (配置为remote,则表示只暴露远程服务)
            if (!Constants.SCOPE_REMOTE.toString().equalsIgnoreCase(scope)) {
                exportLocal(url);
            }
            //如果配置不是local则暴露为远程服务.(配置为local,则表示只暴露远程服务)
            if (! Constants.SCOPE_LOCAL.toString().equalsIgnoreCase(scope) ){
                if (logger.isInfoEnabled()) {
                    logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);
                }
                if (registryURLs != null && registryURLs.size() > 0
                        && url.getParameter("register", true)) {
                    for (URL registryURL : registryURLs) {
                        url = url.addParameterIfAbsent("dynamic", registryURL.getParameter("dynamic"));
                        URL monitorUrl = loadMonitor(registryURL);
                        if (monitorUrl != null) {
                            url = url.addParameterAndEncoded(Constants.MONITOR_KEY, monitorUrl.toFullString());
                        }
                        if (logger.isInfoEnabled()) {
                            logger.info("Register dubbo service " + interfaceClass.getName() + " url " + url + " to registry " + registryURL);
                        }
                        Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));

                        Exporter<?> exporter = protocol.export(invoker);
                        exporters.add(exporter);
                    }
                } else {
                    Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);

                    Exporter<?> exporter = protocol.export(invoker);
                    exporters.add(exporter);
                }
            }
        }
        this.urls.add(url);
  1. 读取配置,生成URL
  2. 获取ConfiguratorFactory的针对指定协议的扩展(这里可以自定义扩展,下面会有一个演示)
  3. 本地服务注册和发布:exportLocal(url);
            ServiceClassHolder.getInstance().pushServiceClass(getServiceClass(ref));

            Exporter<?> exporter = protocol.export(
                    proxyFactory.getInvoker(ref, (Class) interfaceClass, local));
            exporters.add(exporter);
  1. 远程服务注册和发布:
                        Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));

                        Exporter<?> exporter = protocol.export(invoker);
                        exporters.add(exporter);

ConfiguratorFactory扩展

  1. 生成一个配置工厂
    public class DemoDubboConfiguratorFactory implements ConfiguratorFactory{
    
        @Override
        public Configurator getConfigurator(URL url) {
            System.out.println("==============这是一个自定义配置================");
            return new DemoDubboConfigurator(url); 
        }
    
    }
  1. 生成Configurator
    public class DemoDubboConfigurator implements Configurator{
        private URL url;
        public DemoDubboConfigurator(URL url){
            this.url = url;
        }
        
        @Override
        public int compareTo(Configurator o) {
            return 0;
        }
    
        @Override
        public URL getUrl() {
            return this.url;
        }
    
        @Override
        public URL configure(URL url) {
            //  这里是我们对URL进行定制的地方
            return url.addParameter("demoName", "linxm");
        }
    
    }
  1. 书写扩展配置文件:com.alibaba.dubbo.rpc.cluster.ConfiguratorFactory,你应该知道放在哪
dubbo=me.helllp.demo.dubboxStudy.listener.DemoDubboConfiguratorFactory
  1. 运行效果:日志中会输出==============这是一个自定义配置================
服务中的定制内容

下一节我们将会研究URL如何注册到zookeeper的!

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