1.dubbo加载流程
第一步解析：
在dubbo的jar包下，spring启动时会默认加载/MATE-INF/spring.handler文件，该文件下有这么一段内容：
http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler这个DubboNamespaceHandler就是dubbo最初加载的类，它继承了NamespaceHandlerSupport这个类，
DubboNamespaceHandler中代码如下：
在init()方法中，初始化了zk和dubbo相关的配置（application，module，registry，monitor，provider，consumer，protocol，service，reference，annotation 这个标签），将dubbo生成bean交给Spring进行管理。
registerBeanDefinitionParser这个方法点进去，其实是一个HashMap，elementName是key，new DubboBeanDefinitionParser()是value。
接着DubboBeanDefinitionParser这个真正解析类
DubboBeanDefinitionParser继承了BeanDefinitionParser，实现里面的parse方法，这个就是dubbo注册解析的方法，里面只有对dubbo配置文件的解析，内有其他任何调用。
第二部服务暴露：
暴露的入口在ServiceBean这个类中，这个类实现了spring的几个接口类：
InitializingBean 当spring容器初始化完成以后，会调用这个类的afterPropertiesSet方法，所以说这里是dubbo暴露协议的入口。
DisposableBean bean被销毁的时候会调用destroy方法
ApplicationContextAware bean初始化成功后会注入applicationContext对象
ApplicationListener spring容器初始化完成后会触发事件监听
BeanNameAware spring初始化完以后，会获得bean的ID属性
以上几各类是spring相关的东西，如果想要更深入理解，可以百度下这几个类具体看一下，这里就不描述了。
接下来具体看afterPropertiesSet这个方法：
这个代码很长，不过代码易懂，都是对一些初始化配置为空的判断
public void afterPropertiesSet() throws Exception {
if (getProvider() == null) {//判断初始化的config是否为空，初始化完成后，一定不为空，如果真的出现空的情况，会在下面这段代码进行一个相应的处理设置
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
List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>();
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() != null && config.isDefault().booleanValue()) {
providerConfigs.add(config);
}
}
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);
}
}
}
}
if (getApplication() == null//判断appilcation是否为空，初始化完成后，一定不为空，如果真的出现空的情况，会在下面这段代码进行一个相应的处理设置
&& (getProvider() == null || getProvider().getApplication() == null)) {
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;
}
}
if (applicationConfig != null) {
setApplication(applicationConfig);
}
}
}
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;
}
}
if (moduleConfig != null) {
setModule(moduleConfig);
}
}
}
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);
}
}
if (registryConfigs != null && registryConfigs.size() > 0) {
super.setRegistries(registryConfigs);
}
}
}
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;
}
}
if (monitorConfig != null) {
setMonitor(monitorConfig);
}
}
}
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);
}
}
if (protocolConfigs != null && protocolConfigs.size() > 0) {
super.setProtocols(protocolConfigs);
}
}
}
if (getPath() == null || getPath().length() == 0) {
if (beanName != null && beanName.length() > 0
&& getInterface() != null && getInterface().length() > 0
&& beanName.startsWith(getInterface())) {
setPath(beanName);
}
}
if (! isDelay()) {//判断是否延迟加载
export();//这个方法是具体的加载逻辑
}
}
具体加载逻辑export
public synchronized void export() {
if (provider != null) {
if (export == null) {
export = provider.getExport();
}
if (delay == null) {
delay = provider.getDelay();
}
}
if (export != null && ! export.booleanValue()) {
return;
}
if (delay != null && delay > 0) {//延迟加载,睡眠....代码亲民
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();//加载
}
}接下来doExport方法,首先是一系列的判断,通过抛出的异常就可以看出判断的含义
protected synchronized void doExport() {
if (unexported) {//判断是否已经取消发布
throw new IllegalStateException("Already unexported!");
}
if (exported) {//判断是否已经发布
return;
}
exported = true;
if (interfaceName == null || interfaceName.length() == 0) {//判断接口是否为空
throw new IllegalStateException("<dubbo:service interface=\"\" /> interface not allow null!");
}
checkDefault();
if (provider != null) {//判断dubbo里面的配置
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;
generic = true;
} else {
try {
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
.getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
checkInterfaceAndMethods(interfaceClass, methods);
checkRef();
generic = false;
}
if(local !=null){
if(local=="true"){
local=interfaceName+"Local";
}
Class<?> localClass;
try {
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);
}
}
if(stub !=null){
if(stub=="true"){
stub=interfaceName+"Stub";
}
Class<?> stubClass;
try {
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);
}
}
checkApplication();
checkRegistry();
checkProtocol();
appendProperties(this);
checkStubAndMock(interfaceClass);
if (path == null || path.length() == 0) {
path = interfaceName;
}
doExportUrls();
}
继续到doExoportUrls方法
private void doExportUrls() {
List<URL> registryURLs = loadRegistries(true);//获得注册中心的配置
for (ProtocolConfig protocolConfig : protocols) {//从这里可以看出,支持多协议发布
doExportUrlsFor1Protocol(protocolConfig, registryURLs);//两个参数,协议配置,注册中心的url
}
}点进doExportUrlsFor1Protocol方法
这个方法过长，但是可以分段解读，
第一段：获取host
分为4种方法，也可以根据代码看出获取host的优先级
NetUtils.isInvalidLocalHost 这个方法主要是校验ip是否合法
String host = protocolConfig.getHost();//第一种从配置中获取
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();//第二种本机IP地址
} catch (UnknownHostException e) {
logger.warn(e.getMessage(), e);
}
if (NetUtils.isInvalidLocalHost(host)) {
if (registryURLs != null && registryURLs.size() > 0) {
for (URL registryURL : registryURLs) {
try {
Socket socket = new Socket();
try {
SocketAddress addr = new InetSocketAddress(registryURL.getHost(), registryURL.getPort());
socket.connect(addr, 1000);
host = socket.getLocalAddress().getHostAddress();//第三种获取注册中心的主机地址
break;
} finally {
try {
socket.close();
} catch (Throwable e) {}
}
} catch (Exception e) {
logger.warn(e.getMessage(), e);
}
}
}
if (NetUtils.isInvalidLocalHost(host)) {
host = NetUtils.getLocalHost();//第四种遍历本地网卡，返回第一个合理的ip
}
}
}
第二段：获取协议需要暴露的端口
Integer port = protocolConfig.getPort();//获取Protocol的实现类的默认端口
if (provider != null && (port == null || port == 0)) {
port = provider.getPort();
}
final int defaultPort = ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(name).getDefaultPort();//获取配置端口
if (port == null || port == 0) {
port = defaultPort;
}
if (port == null || port <= 0) {
port = getRandomPort(name);//随机端口
if (port == null || port < 0) {
port = NetUtils.getAvailablePort(defaultPort);
putRandomPort(name, port);//设置随机端口
}
logger.warn("Use random available port(" + port + ") for protocol " + name);
}第三段：收集参数，放入map，为服务暴露做准备工作
这个是解析一些参数的，代码太长了，知道这段的含义就行了
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) {
//类型自动转换.
if(argument.getType() != null && argument.getType().length() >0){
Method[] methods = interfaceClass.getMethods();
//遍历所有方法
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 (generic) {
map.put("generic", String.valueOf(true));
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");
}第四段：拼接URL
URL是dubbo对外暴露的服务接口，可以匹配到唯一的一个接口
// 导出服务
String contextPath = protocolConfig.getContextpath();
if ((contextPath == null || contextPath.length() == 0) && provider != null) {
contextPath = provider.getContextpath();
}
//这里将参数封装为URL对象
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);
}第五段：暴露服务
根据配置文件中的scope属性来确定是远程暴露还是本地暴露，
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);
}
//这里对参数做个介绍：
参数1：ref就是接口实现类
参数2：interfaceClass:接口类
参数3：在registryURL上添加参数，key为"export",value就是前面产生的服务协义的url
//proxyFactory的来历
//ExtensionLoader.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension()
// 这个类实例最终就是com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory类的实例，这是由于ProxyFactory类上
// 的注解决定的
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));
Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
}
} else {
//这个是用来没有注册中心的情况下的暴露，可以进行直链
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
}
}
}
this.urls.add(url);最后摘抄网上一张图
