如何把provider的invoker export出去：1）为原始对象加wrapper，生成invoker；2）给invoker加各种filter，启动监听服务；3）注册服务地址
以HelloService为例：
public interface HelloService {
String sayHello();
}
<dubbo:service interface="com.zhang.HelloService" ref="helloService" />
ServiceConfig和<dubbo:service>基本对应上了。
public interface ApplicationListener {
public void onApplicationEvent(ApplicationEvent event);
}
public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, ApplicationContextAware, ApplicationListener, BeanNameAware {
public void onApplicationEvent(ApplicationEvent event) {
if (ContextRefreshedEvent.class.getName().equals(event.getClass().getName())) {
if (isDelay()) {
if (logger.isInfoEnabled()) {
logger.info("The service ready on spring started. service: " + getInterface());
}
export();
}
}
}
}
public class ServiceConfig<T> extends AbstractServiceConfig {
private ProviderConfig provider;
// 是否暴露
protected Boolean export;
private String interfaceName;
private Class<?> interfaceClass;
//即<dubbo:service>的ref对象
private T ref;
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) {
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 {
//关于export和delay的配置好像不怎么用，基本走else分支
doExport();
}
}
protected synchronized void doExport() {
if (unexported) {
throw new IllegalStateException("Already unexported!");
}
if (exported) {
return;
}
if (interfaceName == null || interfaceName.length() == 0) {
throw new IllegalStateException("<dubbo:service interface=\"\" /> interface not allow null!");
}
checkDefault();
if (provider != null) {
if (application == null) {
application = provider.getApplication();
}
if (registries == null) {
registries = provider.getRegistries();
}
if (monitor == null) {
monitor = provider.getMonitor();
}
if (protocols == null) {
protocols = provider.getProtocols();
}
}
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 = Class.forName(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 = Class.forName(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();
checkStubAndMock(interfaceClass);
if (path == null || path.length() == 0) {
path = interfaceName;
}
doExportUrls();
exported = true;
}
}
一、生成invoker
ServiceConfig.doExportUrlsFor1Protocol 代码片段：
// ref就是原始对象
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass,
registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));
// protocol是Protocol$Adpative
Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
以javassist为例，默认从JavassistProxyFactory获取invoker，其实是生成wrapper。
// JavassistProxyFactory
public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) {
// TODO Wrapper类不能正确处理带$的类名。这里的 T proxy 是原始对象
final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);
return new AbstractProxyInvoker<T>(proxy, type, url) {
@Override
protected Object doInvoke(T proxy, String methodName,
Class<?>[] parameterTypes,
Object[] arguments) throws Throwable {
return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);
}
};
}
com.alibaba.dubbo.common.bytecode.Wrapper.makeWrapper(Class<?> c) 方法中生成wrapper类，代码格式化后如下：
public class com.alibaba.dubbo.common.bytecode.Wrapper1 extends Wrapper {
public static String[] pns = null;
public static Map pts = null;
public static String[] mns = { "sayHello" };
public static String[] dmns = { "sayHello" };
public static Class[] mts0 = null;
public String[] getPropertyNames() {
return pns;
}
public boolean hasProperty(String n) {
return pts.containsKey($1);
}
public Class getPropertyType(String n) {
return (Class) pts.get($1);
}
public String[] getMethodNames() {
return mns;
}
public String[] getDeclaredMethodNames() {
return dmns;
}
public void setPropertyValue(Object o, String n, Object v) {
com.zhang.HelloServiceImpl w;
try {
w = ((com.zhang.HelloServiceImpl) $1);
} catch (Throwable e) {
throw new IllegalArgumentException(e);
}
throw new com.alibaba.dubbo.common.bytecode.NoSuchPropertyException(
"Not found property \""
+ $2
+ "\" filed or setter method in class com.zhang.HelloServiceImpl.");
}
public Object getPropertyValue(Object o, String n) {
com.zhang.HelloServiceImpl w;
try {
w = ((com.zhang.HelloServiceImpl) $1);
} catch (Throwable e) {
throw new IllegalArgumentException(e);
}
throw new com.alibaba.dubbo.common.bytecode.NoSuchPropertyException(
"Not found property \""
+ $2
+ "\" filed or setter method in class com.zhang.HelloServiceImpl.");
}
public Object invokeMethod(Object o, String n, Class[] p, Object[] v)
throws java.lang.reflect.InvocationTargetException {
com.zhang.HelloServiceImpl w;
try {
w = ((com.zhang.HelloServiceImpl) $1);
} catch (Throwable e) {
throw new IllegalArgumentException(e);
}
try {
if ("sayHello".equals($2) && $3.length == 0) {
return ($w) w.sayHello();
}
} catch (Throwable e) {
throw new java.lang.reflect.InvocationTargetException(e);
}
throw new com.alibaba.dubbo.common.bytecode.NoSuchMethodException(
"Not found method \"" + $2
+ "\" in class com.zhang.HelloServiceImpl.");
}
}
二、开始export。贴出Protocol$Adpative的代码，重点关注export方法：
package com.alibaba.dubbo.rpc;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
public class Protocol$Adpative implements com.alibaba.dubbo.rpc.Protocol {
public void destroy() {
throw new UnsupportedOperationException(
"method public abstract void com.alibaba.dubbo.rpc.Protocol.destroy() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!");
} public int getDefaultPort() {
throw new UnsupportedOperationException(
"method public abstract int com.alibaba.dubbo.rpc.Protocol.getDefaultPort() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!");
} public com.alibaba.dubbo.rpc.Invoker refer(java.lang.Class arg0,
com.alibaba.dubbo.common.URL arg1) throws java.lang.Class {
if (arg1 == null)
throw new IllegalArgumentException("url == null");
com.alibaba.dubbo.common.URL url = arg1;
String extName = (url.getProtocol() == null ? "dubbo" : url
.getProtocol());
if (extName == null)
throw new IllegalStateException(
"Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url("
+ url.toString() + ") use keys([protocol])");
com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader
.getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class)
.getExtension(extName);
return extension.refer(arg0, arg1);
} public com.alibaba.dubbo.rpc.Exporter export(
com.alibaba.dubbo.rpc.Invoker arg0)
throws com.alibaba.dubbo.rpc.Invoker {
if (arg0 == null)
throw new IllegalArgumentException(
"com.alibaba.dubbo.rpc.Invoker argument == null");
if (arg0.getUrl() == null)
throw new IllegalArgumentException(
"com.alibaba.dubbo.rpc.Invoker argument getUrl() == null");
com.alibaba.dubbo.common.URL url = arg0.getUrl();
// 根据invoker的url，获取扩展名
String extName = (url.getProtocol() == null ? "dubbo" : url
.getProtocol());
if (extName == null)
throw new IllegalStateException(
"Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url("
+ url.toString() + ") use keys([protocol])");
com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader
.getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class)
.getExtension(extName);
return extension.export(arg0);
}
} package com.alibaba.dubbo.rpc.cluster;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
public class Cluster$Adpative implements com.alibaba.dubbo.rpc.cluster.Cluster {
public com.alibaba.dubbo.rpc.Invoker join(
com.alibaba.dubbo.rpc.cluster.Directory arg0)
throws com.alibaba.dubbo.rpc.cluster.Directory {
if (arg0 == null)
throw new IllegalArgumentException(
"com.alibaba.dubbo.rpc.cluster.Directory argument == null");
if (arg0.getUrl() == null)
throw new IllegalArgumentException(
"com.alibaba.dubbo.rpc.cluster.Directory argument getUrl() == null");
com.alibaba.dubbo.common.URL url = arg0.getUrl();
String extName = url.getParameter("cluster", "failover");
if (extName == null)
throw new IllegalStateException(
"Fail to get extension(com.alibaba.dubbo.rpc.cluster.Cluster) name from url("
+ url.toString() + ") use keys([cluster])");
com.alibaba.dubbo.rpc.cluster.Cluster extension = (com.alibaba.dubbo.rpc.cluster.Cluster) ExtensionLoader
.getExtensionLoader(com.alibaba.dubbo.rpc.cluster.Cluster.class)
.getExtension(extName);
// extension是MockClusterWrapper
return extension.join(arg0);
}
}
从调用栈中能看出，Protocol$Adpative.export调用了两次，在Protocol$Adpative的export函数内部，
第一次获取的protocol是 ProtocolListenerWrapper/ProtocolFilterWrapper/RegistryProtocol，
第二次获取的protocol是 ProtocolListenerWrapper/ProtocolFilterWrapper/DubboProtocol。
第一次：ServiceConfig.doExportUrlsFor1Protocol代码片段：
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()));
// protocol是Protocol$Adpative
// invoker的url：registry://127.0.0.1:2181/xxxxx
Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
}
} else {
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url); Exporter<?> exporter = protocol.export(invoker);
exporters.add(exporter);
}
第二次 RegistryProtocol：
// RegistryProtocol
private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker){
String key = getCacheKey(originInvoker);
ExporterChangeableWrapper<T> exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
if (exporter == null) {
synchronized (bounds) {
exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
if (exporter == null) {
final Invoker<?> invokerDelegete =
new InvokerDelegete<T>(originInvoker, getProviderUrl(originInvoker));
//protocol是com.alibaba.dubbo.rpc.Protocol$Adpative
// invoker的url：dubbo://192.168.233.6:20880
exporter = new ExporterChangeableWrapper<T>((Exporter<T>)protocol.export(invokerDelegete), originInvoker);
bounds.put(key, exporter);
}
}
}
return (ExporterChangeableWrapper<T>) exporter;
}
暴露服务主要的步骤可能在这儿了：
// RegistryProtocol
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//export invoker 开启服务
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker);
//registry provider 注册服务
final Registry registry = getRegistry(originInvoker);
final URL registedProviderUrl = getRegistedProviderUrl(originInvoker);
registry.register(registedProviderUrl);
// 订阅override数据
// FIXME 提供者订阅时，会影响同一JVM即暴露服务，又引用同一服务的的场景，因为subscribed以服务名为缓存的key，导致订阅信息覆盖。
final URL overrideSubscribeUrl = getSubscribedOverrideUrl(registedProviderUrl);
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl);
overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
//保证每次export都返回一个新的exporter实例
return new Exporter<T>() {
public Invoker<T> getInvoker() {
return exporter.getInvoker();
}
public void unexport() {
try {
exporter.unexport();
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
try {
registry.unregister(registedProviderUrl);
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
try {
overrideListeners.remove(overrideSubscribeUrl);
registry.unsubscribe(overrideSubscribeUrl, overrideSubscribeListener);
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
}
};
}
在DubboProtocol中export，主要是启动服务：
// DubboProtocol
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
URL url = invoker.getUrl(); // export service.
String key = serviceKey(url);
//DubboExporter封装了invoker，invoker对象是RegistryProtocol$InvokerDelegete
DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
//把exporter放入map中
//key: a/com.zhang.HelloService:20880
//value: DubboExporter
exporterMap.put(key, exporter); //export an stub service for dispaching event
Boolean isStubSupportEvent = url.getParameter(Constants.STUB_EVENT_KEY,Constants.DEFAULT_STUB_EVENT);
Boolean isCallbackservice = url.getParameter(Constants.IS_CALLBACK_SERVICE, false);
if (isStubSupportEvent && !isCallbackservice){
String stubServiceMethods = url.getParameter(Constants.STUB_EVENT_METHODS_KEY);
if (stubServiceMethods == null || stubServiceMethods.length() == 0 ){
if (logger.isWarnEnabled()){
logger.warn(new IllegalStateException("consumer [" +url.getParameter(Constants.INTERFACE_KEY) +
"], has set stubproxy support event ,but no stub methods founded."));
}
} else {
stubServiceMethodsMap.put(url.getServiceKey(), stubServiceMethods);
}
} openServer(url); return exporter;
} private void openServer(URL url) {
// find server.
String key = url.getAddress();
//client 也可以暴露一个只有server可以调用的服务。
boolean isServer = url.getParameter(Constants.IS_SERVER_KEY,true);
if (isServer) {
ExchangeServer server = serverMap.get(key);
if (server == null) {
serverMap.put(key, createServer(url));
} else {
//server支持reset,配合override功能使用
server.reset(url);
}
}
}
private ExchangeServer createServer(URL url) {
//默认开启server关闭时发送readonly事件
url = url.addParameterIfAbsent(Constants.CHANNEL_READONLYEVENT_SENT_KEY, Boolean.TRUE.toString());
//默认开启heartbeat
url = url.addParameterIfAbsent(Constants.HEARTBEAT_KEY, String.valueOf(Constants.DEFAULT_HEARTBEAT));
String str = url.getParameter(Constants.SERVER_KEY, Constants.DEFAULT_REMOTING_SERVER); if (str != null && str.length() > 0 && ! ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str))
throw new RpcException("Unsupported server type: " + str + ", url: " + url); url = url.addParameter(Constants.CODEC_KEY, Version.isCompatibleVersion() ? COMPATIBLE_CODEC_NAME : DubboCodec.NAME);
ExchangeServer server;
try {
//requestHandler是DubboProtocol的一个内部类（ExchangeHandlerAdapter）
server = Exchangers.bind(url, requestHandler);
} catch (RemotingException e) {
throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
}
str = url.getParameter(Constants.CLIENT_KEY);
if (str != null && str.length() > 0) {
Set<String> supportedTypes = ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions();
if (!supportedTypes.contains(str)) {
throw new RpcException("Unsupported client type: " + str);
}
}
return server;
}
绑定requestHandler
// Exchangers
public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
if (url == null) {
throw new IllegalArgumentException("url == null");
}
if (handler == null) {
throw new IllegalArgumentException("handler == null");
}
url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
return getExchanger(url).bind(url, handler);
} // HeaderExchanger
public ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
return new HeaderExchangeServer(Transporters.bind(url, new DecodeHandler(new HeaderExchangeHandler(handler))));
}