dubbo源码阅读-服务订阅(八)之主流程

说明

在api配置，注解配置 可以发现服务订阅是调用RefreceBean的get方法

类图

ReferenceConfig

<1>get

com.alibaba.dubbo.config.ReferenceConfig#get

   public synchronized T get() {
        //是否已经销毁 调用destroy方法会标记为true
        if (destroyed) {
            throw new IllegalStateException("Already destroyed!");
        }
        //是否已经订阅 并生成代理类 避免重复定义
        if (ref == null) {
            //<2>
            init();
        }
        return ref;
    }

<2>init

com.alibaba.dubbo.config.ReferenceConfig#get

->

com.alibaba.dubbo.config.ReferenceConfig#init

    private void init() {
        //是否已经出初始化
        if (initialized) {
            return;
        }
        //标记为初始化
        initialized = true;
        //是否有配置interfaceName
        if (interfaceName == null || interfaceName.length() == 0) {
            throw new IllegalStateException("<dubbo:reference interface="" /> interface not allow null!");
        }
        // 检查是否配置consumer 同时配置参数
        checkDefault();
        //Reference配置参数 //可参考 都是继承同一个父类父类https://www.cnblogs.com/LQBlog/p/12469007.html#autoid-6-5-0
        appendProperties(this);
        //是否是泛型化配置
        if (getGeneric() == null && getConsumer() != null) {
            setGeneric(getConsumer().getGeneric());
        }
        //是否是泛型化接口
        if (ProtocolUtils.isGeneric(getGeneric())) {
            interfaceClass = GenericService.class;
        } else {
            try {
                /**
                 * 反射获得 interface属性配置的class
                 */
                interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
                        .getContextClassLoader());
            } catch (ClassNotFoundException e) {
                throw new IllegalStateException(e.getMessage(), e);
            }
            //这里主要是为了检查 如果配置了methods 方法 在当前config是否存在set方法 具体可看https://www.cnblogs.com/LQBlog/p/12469007.html#autoid-6-2-0
            checkInterfaceAndMethods(interfaceClass, methods);
        }

        /**
         * 设置当前服务访问地址 从系统变量获取
         *  -Dcom.test.UserServiceBo=dubbo://30.8.59.182:20880
         *  优先级最高 将会忽略zk发现
         */
        String resolve = System.getProperty(interfaceName);
        String resolveFile = null;
        if (resolve == null || resolve.length() == 0) {
            resolveFile = System.getProperty("dubbo.resolve.file");
            if (resolveFile == null || resolveFile.length() == 0) {
                /**
                 * 也可以通过dubbo.resolve.file 指定配置的properties地址 进行批量设置
                 *  com.test.UserServiceBo=dubbo://30.8.59.182:20880
                 *  com.test.StudentServiceBo=dubbo://30.8.59.182:20880
                 */
                File userResolveFile = new File(new File(System.getProperty("user.home")), "dubbo-resolve.properties");
                if (userResolveFile.exists()) {
                    resolveFile = userResolveFile.getAbsolutePath();
                }
            }
            if (resolveFile != null && resolveFile.length() > 0) {
                Properties properties = new Properties();
                FileInputStream fis = null;
                try {
                    fis = new FileInputStream(new File(resolveFile));
                    properties.load(fis);
                } catch (IOException e) {
                    throw new IllegalStateException("Unload " + resolveFile + ", cause: " + e.getMessage(), e);
                } finally {
                    try {
                        if (null != fis) fis.close();
                    } catch (IOException e) {
                        logger.warn(e.getMessage(), e);
                    }
                }
                resolve = properties.getProperty(interfaceName);
            }
        }
        if (resolve != null && resolve.length() > 0) {
            url = resolve;
            if (logger.isWarnEnabled()) {
                if (resolveFile != null) {
                    logger.warn("Using default dubbo resolve file " + resolveFile + " replace " + interfaceName + "" + resolve + " to p2p invoke remote service.");
                } else {
                    logger.warn("Using -D" + interfaceName + "=" + resolve + " to p2p invoke remote service.");
                }
            }
        }
        /**
         * 以前都是根据优先级获取对应配置
         */
        if (consumer != null) {
            if (application == null) {
                application = consumer.getApplication();
            }
            if (module == null) {
                module = consumer.getModule();
            }
            if (registries == null) {
                registries = consumer.getRegistries();
            }
            if (monitor == null) {
                monitor = consumer.getMonitor();
            }
        }
        if (module != null) {
            if (registries == null) {
                registries = module.getRegistries();
            }
            if (monitor == null) {
                monitor = module.getMonitor();
            }
        }
        if (application != null) {
            if (registries == null) {
                registries = application.getRegistries();
            }
            if (monitor == null) {
                monitor = application.getMonitor();
            }
        }
        //检查是否配置application 如果没有则 初始化
        checkApplication();
        //检查stup接口配置
        checkStub(interfaceClass);
        //检查mock接口配置
        checkMock(interfaceClass);

        //封装参数
        Map<String, String> map = new HashMap<String, String>();
        Map<Object, Object> attributes = new HashMap<Object, Object>();
        map.put(Constants.SIDE_KEY, Constants.CONSUMER_SIDE);
        //版本
        map.put(Constants.DUBBO_VERSION_KEY, Version.getProtocolVersion());
        //日期
        map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));
        //进程号
        if (ConfigUtils.getPid() > 0) {
            map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));
        }
        //非泛型化接口
        if (!isGeneric()) {
            //或version
            String revision = Version.getVersion(interfaceClass, version);
            //参数追加version
            if (revision != null && revision.length() > 0) {
                map.put("revision", revision);
            }

            //反射获取方法名字
            String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();
            if (methods.length == 0) {
                logger.warn("NO method found in service interface " + interfaceClass.getName());
                map.put("methods", Constants.ANY_VALUE);
            } else {
                //追加到参数里面
                map.put("methods", StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));
            }
        }
        map.put(Constants.INTERFACE_KEY, interfaceName);
        //反射获得所有get 基本类型方法 以及parameter 封装到map
        appendParameters(map, application);
        //反射获得所有get 基本类型方法 以及parameter 封装到map
        appendParameters(map, module);
        //反射获得所有get 基本类型方法 以及parameter 封装到map 前缀为default
        appendParameters(map, consumer, Constants.DEFAULT_KEY);
        //反射获得当给前对象的所有方法 并封装到map
        appendParameters(map, this);
        //group/+interfaacename+version
        String prefix = StringUtils.getServiceKey(map);
        //如果配置了method 封装到map
        if (methods != null && !methods.isEmpty()) {
            for (MethodConfig method : methods) {
                appendParameters(map, method, method.getName());
                String retryKey = method.getName() + ".retry";
                if (map.containsKey(retryKey)) {
                    String retryValue = map.remove(retryKey);
                    if ("false".equals(retryValue)) {
                        map.put(method.getName() + ".retries", "0");
                    }
                }
                appendAttributes(attributes, method, prefix + "." + method.getName());
                checkAndConvertImplicitConfig(method, map, attributes);
            }
        }

        //获得注册中心地址 key
        String hostToRegistry = ConfigUtils.getSystemProperty(Constants.DUBBO_IP_TO_REGISTRY);
        if (hostToRegistry == null || hostToRegistry.length() == 0) {
            hostToRegistry = NetUtils.getLocalHost();
        } else if (isInvalidLocalHost(hostToRegistry)) {
            throw new IllegalArgumentException("Specified invalid registry ip from property:" + Constants.DUBBO_IP_TO_REGISTRY + ", value:" + hostToRegistry);
        }
        map.put(Constants.REGISTER_IP_KEY, hostToRegistry);

        //attributes are stored by system context.
        StaticContext.getSystemContext().putAll(attributes);
        //<3>生成代理对象
        ref = createProxy(map);
        ConsumerModel consumerModel = new ConsumerModel(getUniqueServiceName(), this, ref, interfaceClass.getMethods());
        //通过ConsumerModel 封装到订阅列表
        ApplicationModel.initConsumerModel(getUniqueServiceName(), consumerModel);
    }

<3>createProxy

rivate T createProxy(Map<String, String> map) {
        URL tmpUrl = new URL("temp", "localhost", 0, map);
        final boolean isJvmRefer;
        //是否是本地调用
        if (isInjvm() == null) {
            if (url != null && url.length() > 0) { // if a url is specified, don't do local reference
                isJvmRefer = false;
                //根据url配置判断是否是本地调用
            } else if (InjvmProtocol.getInjvmProtocol().isInjvmRefer(tmpUrl)) {
                // by default, reference local service if there is
                isJvmRefer = true;
            } else {
                isJvmRefer = false;
            }
        } else {
            isJvmRefer = isInjvm().booleanValue();
        }

        //如果是本地引用
        if (isJvmRefer) {
            //组织url为injvm://127.0.0.1
            URL url = new URL(Constants.LOCAL_PROTOCOL, NetUtils.LOCALHOST, 0, interfaceClass.getName()).addParameters(map);
            /**
             * SPI扩展点
             * private static final Protocol refprotocol = ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension();
             */
            invoker = refprotocol.refer(interfaceClass, url);
            if (logger.isInfoEnabled()) {
                logger.info("Using injvm service " + interfaceClass.getName());
            }
        } else {
            //如果我们手动配置了url;隔开 追加到urls列表
            if (url != null && url.length() > 0) { // user specified URL, could be peer-to-peer address, or register center's address.
                // 拆分地址成数组，使用 ";" 分隔。
                String[] us = Constants.SEMICOLON_SPLIT_PATTERN.split(url);
                // 循环数组，添加到 `url` 中。
                if (us != null && us.length > 0) {
                    for (String u : us) {
                        // 创建 URL 对象
                        URL url = URL.valueOf(u);
                        // 设置默认路径
                        if (url.getPath() == null || url.getPath().length() == 0) {
                            url = url.setPath(interfaceName);
                        }
                        // 注册中心的地址，带上服务引用的配置参数
                        if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
                            urls.add(url.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map)));
                        } else {
                            // 服务提供者的地址
                            urls.add(ClusterUtils.mergeUrl(url, map));
                        }
                    }
                }
            } else { // assemble URL from register center's configuration
                //获取注册中心地址 具体可以看你https://www.cnblogs.com/LQBlog/p/12469007.html#autoid-6-10-0
                List<URL> us = loadRegistries(false);
                if (us != null && !us.isEmpty()) {
                    for (URL u : us) {
                        //加载Monitor 使用例子https://blog.csdn.net/sunhuaqiang1/article/details/80141651
                        URL monitorUrl = loadMonitor(u);
                        if (monitorUrl != null) {
                            map.put(Constants.MONITOR_KEY, URL.encode(monitorUrl.toFullString()));
                        }
                        //添加refer标识 标识是从注册中心地尼公约
                        urls.add(u.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map)));
                    }
                }
                if (urls.isEmpty()) {
                    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.");
                }
            }
             //  // 单 `urls` 时，引用服务，返回 Invoker 对象
            if (urls.size() == 1) {
                /**
                 * Protocol 取得registryProtocol 不过会被代理 具体可以看 https://www.cnblogs.com/LQBlog/p/12470179.html#autoid-2-0-0
                 * 默认是registry SPI扩展 private static final Protocol refprotocol = ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension();
                 */
                invoker = refprotocol.refer(interfaceClass, urls.get(0));
            } else {
                //集群订阅
                List<Invoker<?>> invokers = new ArrayList<Invoker<?>>();
                URL registryURL = null;
                // 循环 `urls` ，引用服务，返回 Invoker 对象
                for (URL url : urls) {
                    // 引用服务
                    invokers.add(refprotocol.refer(interfaceClass, url));
                    // 使用最后一个注册中心的 URL
                    if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
                        registryURL = url; // use last registry url
                    }
                }

                //  // 有注册中心
                if (registryURL != null) { // registry url is available
                    // 对有注册中心的 Cluster 只用 AvailableCluster
                    // use AvailableCluster only when register's cluster is available
                    URL u = registryURL.addParameterIfAbsent(Constants.CLUSTER_KEY, AvailableCluster.NAME);
                    invoker = cluster.join(new StaticDirectory(u, invokers));
                    // 无注册中心，全部都是服务直连
                } else { // not a registry url
                    invoker = cluster.join(new StaticDirectory(invokers));
                }
            }
        }

        //是否配置了启动检查
        Boolean c = check;
        if (c == null && consumer != null) {
            c = consumer.isCheck();
        }
        if (c == null) {
            c = true; // default true
        }
        if (c && !invoker.isAvailable()) {
            // make it possible for consumer to retry later if provider is temporarily unavailable
            initialized = false;
            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());
        }
        // 创建代理类
        return (T) proxyFactory.getProxy(invoker);
    }