Dubbo源码学习--服务是如何引用的

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Dubbo源码学习文章目录

ReferenceBean

跟服务引用一样，Dubbo的reference配置会被转成ReferenceBean类,ReferenceBean实现了InitializingBean接口，直接看afterPropertiesSet()也就是spring为Bean提供的初始化方法

方法调用顺序afterPropertiesSet() -> getObject() -> get() -> init() -> createProxy()

afterPropertiesSet()

afterPropertiesSet()作用为装载应用信息、注册、模块、监控等配置，然后调用getObject()

    public void afterPropertiesSet() throws Exception {
        //.....
        setApplication(applicationConfig);
        //.....
        setModule(moduleConfig);
        //.....
        super.setRegistries(registryConfigs);
        //.....
        Boolean b = isInit();
        if (b == null && getConsumer() != null) {
            b = getConsumer().isInit();
        }
        if (b != null && b.booleanValue()) {
            getObject();
        }
    }

getObject()

getObject() 返回 get() 执行结果

    public Object getObject() throws Exception {
        return get();
    }

get()

get() 如果接口代理类（ref) 为空则调用 init() 生成接口代理类

    public synchronized T get() {
        if (destroyed){
            throw new IllegalStateException("Already destroyed!");
        }
    	if (ref == null) {
    		init();
    	}
    	return ref;
    }

init()

init() 根据配置生成Map 然后调用 createProxy() 生成代理类

    ref = createProxy(map);

createProxy()

具体作用见注释

	private T createProxy(Map<String, String> map) {
        //1. 创建临时Url
		URL tmpUrl = new URL("temp", "localhost", 0, map);
		final boolean isJvmRefer;
        // 省略部分代码.....
        //2.判断是否暴漏本地服务
		if (isJvmRefer) {
			URL url = new URL(Constants.LOCAL_PROTOCOL, NetUtils.LOCALHOST, 0, interfaceClass.getName()).addParameters(map);
			invoker = refprotocol.refer(interfaceClass, url);
        // 省略部分代码.....
		} else {
            //3.判断用户指定URL，指定的URL可能是对点对直连地址，也可能是注册中心URL
            if (url != null && url.length() > 0) {
                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 {
                //4. 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.");
                }
            }
            // 5.调用refprotocol.refer()
            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));
                }
            }
        }
        // 省略.....
        // 6.创建服务代理
        return (T) proxyFactory.getProxy(invoker);
    }

RegistryProtocol

refprotocol.refer()

refprotocol.refer() 先后经过修饰类 ProtocolFilterWrapper、ProtocolListenerWrapper 最后执行RegistryProtocol

ProtocolFilterWrapper -> ProtocolListenerWrapper

    //ProtocolFilterWrapper
    public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
        if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
            return protocol.refer(type, url);
        }
        return buildInvokerChain(protocol.refer(type, url), Constants.REFERENCE_FILTER_KEY, Constants.CONSUMER);
    }

    //ProtocolListenerWrapper
    public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
        if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
            return protocol.refer(type, url);
        }
        return new ListenerInvokerWrapper<T>(protocol.refer(type, url),
                Collections.unmodifiableList(
                        ExtensionLoader.getExtensionLoader(InvokerListener.class)
                        .getActivateExtension(url, Constants.INVOKER_LISTENER_KEY)));
    }

RegistryProtocol

  @SuppressWarnings("unchecked")
	public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
        // Constants.REGISTRY_KEY: registry
        // Constants.DEFAULT_REGISTRY: dubbo
        url = url.setProtocol(url.getParameter(Constants.REGISTRY_KEY, Constants.DEFAULT_REGISTRY)).removeParameter(Constants.REGISTRY_KEY);
        Registry registry = registryFactory.getRegistry(url);
        if (RegistryService.class.equals(type)) {
        	return proxyFactory.getInvoker((T) registry, type, url);
        }
        // 配置Group信息
        // group="a,b" or group="*"
        Map<String, String> qs = StringUtils.parseQueryString(url.getParameterAndDecoded(Constants.REFER_KEY)); // Constants.REFER_KEY:refer
        String group = qs.get(Constants.GROUP_KEY);
        if (group != null && group.length() > 0 ) {
            if ( ( Constants.COMMA_SPLIT_PATTERN.split( group ) ).length > 1
                    || "*".equals( group ) ) {
                return doRefer( getMergeableCluster(), registry, type, url );
            }
        }
        return doRefer(cluster, registry, type, url);
    }

doRefer()

1. 调用FailbackRegistry.register() 在注册中心注册消费者subscribeUrl
2. 调用FailbackRegistry.subscribe() 订阅注册中心subscribeUrl

    private <T> Invoker<T> doRefer(Cluster cluster, Registry registry, Class<T> type, URL url) {
        RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);
        directory.setRegistry(registry);
        directory.setProtocol(protocol);
        // Constants.CONSUMER_PROTOCOL: consumer
        URL subscribeUrl = new URL(Constants.CONSUMER_PROTOCOL, NetUtils.getLocalHost(), 0, type.getName(), directory.getUrl().getParameters());

        //consumer://10.9.22.12/com.**.ShopService?application=test&check=false&dubbo=2.8.4
        //&interface=com.**.ShopService&methods=getList&pid=6168&retries=1&revision=1.0-SNAPSHOT
        //&side=consumer&timeout=6000&timestamp=1484275807134&version=1.0
        if (! Constants.ANY_VALUE.equals(url.getServiceInterface())
                && url.getParameter(Constants.REGISTER_KEY, true)) {
            registry.register(subscribeUrl.addParameters(Constants.CATEGORY_KEY, Constants.CONSUMERS_CATEGORY,
                    Constants.CHECK_KEY, String.valueOf(false)));
        }
        directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,
                Constants.PROVIDERS_CATEGORY
                + "," + Constants.CONFIGURATORS_CATEGORY
                + "," + Constants.ROUTERS_CATEGORY));
        return cluster.join(directory);
    }

引用服务时序