如上图所看到的的Dubbo的暴露服务的过程，不难看出它也和消费者端非常像，也须要一个像reference的对象来维护service关联的全部对象及其属性。这里的reference就是provider。因为ServiceBean实现了
InitializingBean接口，全部在Spring实例化这个bean后会调用接口方法afterPropertiesSet：
public void afterPropertiesSet() throws Exception {
//假设没有配置provider
if (getProvider() == null) {
//获取IOC容器里的全部provider
Map<String, ProviderConfig> providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false);
if (providerConfigMap != null && providerConfigMap.size() > 0) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if ((protocolConfigMap == null || protocolConfigMap.size() == 0)
&& providerConfigMap.size() > 1) { // 兼容旧版本号
List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>();
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() != null && config.isDefault().booleanValue()) {
providerConfigs.add(config);
}
}
//关联全部providers
if (providerConfigs.size() > 0) {
setProviders(providerConfigs);
}
} else {
ProviderConfig providerConfig = null;
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (providerConfig != null) {
throw new IllegalStateException("Duplicate provider configs: " + providerConfig + " and " + config);
}
providerConfig = config;
}
}
if (providerConfig != null) {
setProvider(providerConfig);
}
}
}
}
//假设没有配置application，且没有配置provider
if (getApplication() == null
&& (getProvider() == null || getProvider().getApplication() == null)) {
//获取全部applications
Map<String, ApplicationConfig> applicationConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ApplicationConfig.class, false, false);
if (applicationConfigMap != null && applicationConfigMap.size() > 0) {
ApplicationConfig applicationConfig = null;
for (ApplicationConfig config : applicationConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (applicationConfig != null) {
throw new IllegalStateException("Duplicate application configs: " + applicationConfig + " and " + config);
}
applicationConfig = config;
}
}
//关联application
if (applicationConfig != null) {
setApplication(applicationConfig);
}
}
}
//假设没有配置module。且没有配置provider
if (getModule() == null
&& (getProvider() == null || getProvider().getModule() == null)) {
Map<String, ModuleConfig> moduleConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ModuleConfig.class, false, false);
if (moduleConfigMap != null && moduleConfigMap.size() > 0) {
ModuleConfig moduleConfig = null;
for (ModuleConfig config : moduleConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (moduleConfig != null) {
throw new IllegalStateException("Duplicate module configs: " + moduleConfig + " and " + config);
}
moduleConfig = config;
}
}
//关联module
if (moduleConfig != null) {
setModule(moduleConfig);
}
}
}
//假设没有配置registries。且没有配置provider
if ((getRegistries() == null || getRegistries().size() == 0)
&& (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().size() == 0)
&& (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().size() == 0)) {
Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
if (registryConfigMap != null && registryConfigMap.size() > 0) {
List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
for (RegistryConfig config : registryConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
registryConfigs.add(config);
}
}
//关联registries
if (registryConfigs != null && registryConfigs.size() > 0) {
super.setRegistries(registryConfigs);
}
}
}
//假设没有配置monitor，且没有配置provider
if (getMonitor() == null
&& (getProvider() == null || getProvider().getMonitor() == null)
&& (getApplication() == null || getApplication().getMonitor() == null)) {
Map<String, MonitorConfig> monitorConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MonitorConfig.class, false, false);
if (monitorConfigMap != null && monitorConfigMap.size() > 0) {
MonitorConfig monitorConfig = null;
for (MonitorConfig config : monitorConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
if (monitorConfig != null) {
throw new IllegalStateException("Duplicate monitor configs: " + monitorConfig + " and " + config);
}
monitorConfig = config;
}
}
//关联monitor
if (monitorConfig != null) {
setMonitor(monitorConfig);
}
}
}
//假设没有配置protocol，且没有配置provider
if ((getProtocols() == null || getProtocols().size() == 0)
&& (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().size() == 0)) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if (protocolConfigMap != null && protocolConfigMap.size() > 0) {
List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
for (ProtocolConfig config : protocolConfigMap.values()) {
if (config.isDefault() == null || config.isDefault().booleanValue()) {
protocolConfigs.add(config);
}
}
//关联protocol
if (protocolConfigs != null && protocolConfigs.size() > 0) {
super.setProtocols(protocolConfigs);
}
}
}
//假设没有配置path
if (getPath() == null || getPath().length() == 0) {
if (beanName != null && beanName.length() > 0
&& getInterface() != null && getInterface().length() > 0
&& beanName.startsWith(getInterface())) {
setPath(beanName);
}
}
//暴露provider
if (! isDelay()) {
export();
}
}
Dubbo在确认了全部相关对象都配置后调用export方法開始暴露过程：
public synchronized void export() {
//假设provider没有配置
if (provider != null) {
//假设exporter没有配置使用provider所关联的exporter
if (export == null) {
export = provider.getExport();
}
//假设delay（延迟暴露）没有配置，获取provider的delay
if (delay == null) {
delay = provider.getDelay();
}
}
//假设不须要暴露接口则直接返回
if (export != null && ! export.booleanValue()) {
return;
}
//假设延迟暴露的时间（毫秒级）是存在的，开启线程并等待delay毫秒后開始暴露接口，否则直接运行暴露接口过程
if (delay != null && delay > 0) {
Thread thread = new Thread(new Runnable() {
public void run() {
try {
Thread.sleep(delay);
} catch (Throwable e) {
}
doExport();
}
});
thread.setDaemon(true);
thread.setName("DelayExportServiceThread");
thread.start();
} else {
doExport();
}
}protected synchronized void doExport() {
//假设不须要暴露接口则抛出异常
if (unexported) {
throw new IllegalStateException("Already unexported!");
}
//假设已经暴露则不须要反复暴露
if (exported) {
return;
}
exported = true;
//假设interfaceName没配置（这样dubbo就无法找到须要暴露的service对象）则抛出异常
if (interfaceName == null || interfaceName.length() == 0) {
throw new IllegalStateException("<dubbo:service interface="" /> interface not allow null!");
}
checkDefault();
//provider已经配置的情况下，假设application、module、registries、monitor、protocol中有未配置的均能够从provider获取
if (provider != null) {
if (application == null) {
application = provider.getApplication();
}
if (module == null) {
module = provider.getModule();
}
if (registries == null) {
registries = provider.getRegistries();
}
if (monitor == null) {
monitor = provider.getMonitor();
}
if (protocols == null) {
protocols = provider.getProtocols();
}
}
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();
}
}
if (ref instanceof GenericService) {
interfaceClass = GenericService.class;
if (StringUtils.isEmpty(generic)) {
generic = Boolean.TRUE.toString();
}
} else {
try {
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
.getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
checkInterfaceAndMethods(interfaceClass, methods);
checkRef();
generic = Boolean.FALSE.toString();
}
//假设是本地服务
if(local !=null){
//假设是本地服务在interfaceName属性后面加上Local
if(local=="true"){
local=interfaceName+"Local";
}
Class<?> localClass;
try {
//载入service
localClass = ClassHelper.forNameWithThreadContextClassLoader(local);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if(!interfaceClass.isAssignableFrom(localClass)){
throw new IllegalStateException("The local implemention class " + localClass.getName() + " not implement interface " + interfaceName);
}
}
//假设是远程服务
if(stub !=null){
if(stub=="true"){
stub=interfaceName+"Stub";
}
Class<?> stubClass;
try {
//载入service
stubClass = ClassHelper.forNameWithThreadContextClassLoader(stub);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if(!interfaceClass.isAssignableFrom(stubClass)){
throw new IllegalStateException("The stub implemention class " + stubClass.getName() + " not implement interface " + interfaceName);
}
}
//检查application
checkApplication();
//检查registries
checkRegistry();
//检查protocol
checkProtocol();
//将全部这些对象的属性关联到provider
appendProperties(this);
checkStubAndMock(interfaceClass);
if (path == null || path.length() == 0) {
path = interfaceName;
}
//暴露地址
doExportUrls();
}private void doExportUrls() {
//将注冊的全部url匹配上相应的协议在服务端暴露出来
List<URL> registryURLs = loadRegistries(true);
for (ProtocolConfig protocolConfig : protocols) {
doExportUrlsFor1Protocol(protocolConfig, registryURLs);
}
}private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
//假设没配置protocol则默认使用dubbo协议
String name = protocolConfig.getName();
if (name == null || name.length() == 0) {
name = "dubbo";
}
//获取主机地址
String host = protocolConfig.getHost();
if (provider != null && (host == null || host.length() == 0)) {
host = provider.getHost();
}
boolean anyhost = false;
if (NetUtils.isInvalidLocalHost(host)) {
anyhost = true;
try {
host = InetAddress.getLocalHost().getHostAddress();
} catch (UnknownHostException e) {
logger.warn(e.getMessage(), e);
}
if (NetUtils.isInvalidLocalHost(host)) {
if (registryURLs != null && registryURLs.size() > 0) {
for (URL registryURL : registryURLs) {
try {
//创建socket，连接到注冊中心
Socket socket = new Socket();
try {
SocketAddress addr = new InetSocketAddress(registryURL.getHost(), registryURL.getPort());
socket.connect(addr, 1000);
//获取服务所在主机地址
host = socket.getLocalAddress().getHostAddress();
break;
} finally {
try {
socket.close();
} catch (Throwable e) {}
}
} catch (Exception e) {
logger.warn(e.getMessage(), e);
}
}
}
if (NetUtils.isInvalidLocalHost(host)) {
host = NetUtils.getLocalHost();
}
}
}
//获取协议接口号
Integer port = protocolConfig.getPort();
if (provider != null && (port == null || port == 0)) {
port = provider.getPort();
}
final int defaultPort = ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(name).getDefaultPort();
if (port == null || port == 0) {
port = defaultPort;
}
if (port == null || port <= 0) {
port = getRandomPort(name);
if (port == null || port < 0) {
port = NetUtils.getAvailablePort(defaultPort);
putRandomPort(name, port);
}
logger.warn("Use random available port(" + port + ") for protocol " + name);
}
//获取application、module、provider、protocol、exporter、registries、monitor全部属性
Map<String, String> map = new HashMap<String, String>();
if (anyhost) {
map.put(Constants.ANYHOST_KEY, "true");
}
map.put(Constants.SIDE_KEY, Constants.PROVIDER_SIDE);
map.put(Constants.DUBBO_VERSION_KEY, Version.getVersion());
map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));
if (ConfigUtils.getPid() > 0) {
map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));
}
appendParameters(map, application);
appendParameters(map, module);
appendParameters(map, provider, Constants.DEFAULT_KEY);
appendParameters(map, protocolConfig);
appendParameters(map, this);
if (methods != null && methods.size() > 0) {
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");
}
}
List<ArgumentConfig> arguments = method.getArguments();
if (arguments != null && arguments.size() > 0) {
for (ArgumentConfig argument : arguments) {
//类型自己主动转换.
if(argument.getType() != null && argument.getType().length() >0){
Method[] methods = interfaceClass.getMethods();
//遍历全部方法
if(methods != null && methods.length > 0){
for (int i = 0; i < methods.length; i++) {
String methodName = methods[i].getName();
//匹配方法名称，获取方法签名.
if(methodName.equals(method.getName())){
Class<?>[] argtypes = methods[i].getParameterTypes();
//一个方法中单个callback
if (argument.getIndex() != -1 ){
if (argtypes[argument.getIndex()].getName().equals(argument.getType())){
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
}else {
throw new IllegalArgumentException("argument config error : the index attribute and type attirbute not match :index :"+argument.getIndex() + ", type:" + argument.getType());
}
} else {
//一个方法中多个callback
for (int j = 0 ;j<argtypes.length ;j++) {
Class<?> argclazz = argtypes[j];
if (argclazz.getName().equals(argument.getType())){
appendParameters(map, argument, method.getName() + "." + j);
if (argument.getIndex() != -1 && argument.getIndex() != j){
throw new IllegalArgumentException("argument config error : the index attribute and type attirbute not match :index :"+argument.getIndex() + ", type:" + argument.getType());
}
}
}
}
}
}
}
}else if(argument.getIndex() != -1){
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
}else {
throw new IllegalArgumentException("argument config must set index or type attribute.eg: <dubbo:argument index='0' .../> or <dubbo:argument type=xxx .../>");
}
}
}
} // end of methods for
}
if (ProtocolUtils.isGeneric(generic)) {
map.put("generic", generic);
map.put("methods", Constants.ANY_VALUE);
} else {
String revision = Version.getVersion(interfaceClass, version);
if (revision != null && revision.length() > 0) {
map.put("revision", revision);
}
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 {
map.put("methods", StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));
}
}
if (! ConfigUtils.isEmpty(token)) {
if (ConfigUtils.isDefault(token)) {
map.put("token", UUID.randomUUID().toString());
} else {
map.put("token", token);
}
}
if ("injvm".equals(protocolConfig.getName())) {
protocolConfig.setRegister(false);
map.put("notify", "false");
}
// 导出服务
String contextPath = protocolConfig.getContextpath();
if ((contextPath == null || contextPath.length() == 0) && provider != null) {
contextPath = provider.getContextpath();
}
//创建服务所在url
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，则表示仅仅暴露远程服务)
if (!Constants.SCOPE_REMOTE.toString().equalsIgnoreCase(scope)) {
//暴露的地址是localhost所以远端无法訪问
exportLocal(url);
}
//假设配置不是local则暴露为远程服务.(配置为local，则表示仅仅暴露远程服务)
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);
}
//获取invoker
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));
//依据协议将invoker暴露成exporter，详细过程是创建一个ExchangeServer，它会绑定一个ServerSocket到配置端口
Exporter<?> exporter = protocol.export(invoker);
//将创建的exporter放进链表便于管理
exporters.add(exporter);
}
} else {
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
}
}
}
this.urls.add(url);
}
整个暴露服务的流程就是首先检查配置是否完整然后获取协议和port信息，通知registries自己已经注冊能够提供服务最后创建Server绑定port。这样用户就能够从配置的信息连接到Server并和Server通信远程调用方法了。