dubbo客户端源码分析(一)
rpc框架有很多,公司自研、开源的thrift、dubbo、grpc等。我用过几个框架,了解了一下实现原理,客户端基本都是用代理实现,jdk动态代理、cglib等。最近一段时间想了解一下dubbo源码,看下工作原理。今天看了一下客户端初始化源码
<?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.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"> <dubbo:application name="demo-consumer"/> <!--<dubbo:registry address="multicast://224.5.6.7:1234"/>--> <dubbo:registry address="zookeeper://127.0.0.1:2181" /> <dubbo:reference id="demoService" interface="com.gxf.dubbo.demo.DemoSerivce"/> </beans>
这个是dubbo客户端配置,注册中心是本地zk。其中,dubbo是阿里基于spring扩展的schema
https://gist.github.com/dchjmichael/07dfd189c4c29bab63ec
这个文档关于spring schema扩展用法写的很不错,要定义xsd, handler, 解析xml的parser
http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler
这是dubbo的spring-handler.xml,可以找到spring handler
1 public class DubboNamespaceHandler extends NamespaceHandlerSupport { 2 3 static { 4 Version.checkDuplicate(DubboNamespaceHandler.class); 5 } 6 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 } 19 20 }
这里我们关注客户端,看reference相关的就可以了,看下DubboBeanDefinitionParser
类的内容有点多,主要工作是注入了一个ReferenceBean的bean
我们可以看下这个类
public class ReferenceBean<T> extends ReferenceConfig<T> implements FactoryBean, ApplicationContextAware, InitializingBean, DisposableBean {
这个类实现了FactoryBean, InitializingBean这个就有点生成动态代理的套路了
我们看getObject()方法
public Object getObject() throws Exception { return get(); }
进入get()方法
public synchronized T get() { if (destroyed) { throw new IllegalStateException("Already destroyed!"); } if (ref == null) { init(); } return ref; }
跟进init()方法
ref = createProxy(map);
init()方法内容有点多,主要看下这个段, ref也是getBean()返回的对象,这里看方法名可以推测是用的代理
private T createProxy(Map<String, String> map) { URL tmpUrl = new URL("temp", "localhost", 0, map); final boolean isJvmRefer; if (isInjvm() == null) { if (url != null && url.length() > 0) { //指定URL的情况下,不做本地引用 isJvmRefer = false; } else if (InjvmProtocol.getInjvmProtocol().isInjvmRefer(tmpUrl)) { //默认情况下如果本地有服务暴露,则引用本地服务. isJvmRefer = true; } else { isJvmRefer = false; } } else { isJvmRefer = isInjvm().booleanValue(); } if (isJvmRefer) { URL url = new URL(Constants.LOCAL_PROTOCOL, NetUtils.LOCALHOST, 0, interfaceClass.getName()).addParameters(map); invoker = refprotocol.refer(interfaceClass, url); if (logger.isInfoEnabled()) { logger.info("Using injvm service " + interfaceClass.getName()); } } else { if (url != null && url.length() > 0) { // 用户指定URL,指定的URL可能是对点对直连地址,也可能是注册中心URL String[] us = Constants.SEMICOLON_SPLIT_PATTERN.split(url); if (us != null && us.length > 0) { for (String u : us) { URL url = URL.valueOf(u); if (url.getPath() == null || url.getPath().length() == 0) { url = url.setPath(interfaceName); } if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) { urls.add(url.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map))); } else { urls.add(ClusterUtils.mergeUrl(url, map)); } } } } else { // 通过注册中心配置拼装URL List<URL> us = loadRegistries(false); if (us != null && us.size() > 0) { for (URL u : us) { URL monitorUrl = loadMonitor(u); if (monitorUrl != null) { map.put(Constants.MONITOR_KEY, URL.encode(monitorUrl.toFullString())); } urls.add(u.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map))); } } if (urls == null || urls.size() == 0) { throw new IllegalStateException("No such any registry to reference " + interfaceName + " on the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion() + ", please config <dubbo:registry address=\"...\" /> to your spring config."); } } if (urls.size() == 1) { invoker = refprotocol.refer(interfaceClass, urls.get(0)); } else { List<Invoker<?>> invokers = new ArrayList<Invoker<?>>(); URL registryURL = null; for (URL url : urls) { invokers.add(refprotocol.refer(interfaceClass, url)); if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) { registryURL = url; // 用了最后一个registry url } } if (registryURL != null) { // 有 注册中心协议的URL // 对有注册中心的Cluster 只用 AvailableCluster URL u = registryURL.addParameter(Constants.CLUSTER_KEY, AvailableCluster.NAME); invoker = cluster.join(new StaticDirectory(u, invokers)); } else { // 不是 注册中心的URL invoker = cluster.join(new StaticDirectory(invokers)); } } } Boolean c = check; if (c == null && consumer != null) { c = consumer.isCheck(); } if (c == null) { c = true; // default true } if (c && !invoker.isAvailable()) { throw new IllegalStateException("Failed to check the status of the service " + interfaceName + ". No provider available for the service " + (group == null ? "" : group + "/") + interfaceName + (version == null ? "" : ":" + version) + " from the url " + invoker.getUrl() + " to the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion()); } if (logger.isInfoEnabled()) { logger.info("Refer dubbo service " + interfaceClass.getName() + " from url " + invoker.getUrl()); } // 创建服务代理 return (T) proxyFactory.getProxy(invoker); }
这个方法内容也挺多,今天没看完。应该是代理模式,
这里有个有意思的地方是,如果服务端没有启动在zk中注册,这里生成客户端代理的时候会抛异常。这个是后面需要去分析源码的,还有server端如何暴露服务的,即监听对应的端口,接收客户端的请求。以及在zk里面保存的内容
今天还发现一个有意思的地方,dubbo里面有泛化调用。看了泛化调用部分代码,感觉公司用的泛化调用,应该是参考了dubbo的