dubbo rpc redis 等等

dubbo-demo/dubbo-http-demo-consumer/pom.xml

@@ -52,14 +52,11 @@ limitations under the License.
             <groupId>com.alibaba</groupId>
             <artifactId>dubbo-cluster</artifactId>
         </dependency>
-        <!--<dependency>-->
-            <!--<groupId>com.alibaba</groupId>-->
-            <!--<artifactId>dubbo-rpc-http</artifactId>-->
-        <!--</dependency>-->
-        <!--<dependency>-->
-            <!--<groupId>com.alibaba</groupId>-->
-            <!--<artifactId>dubbo-remoting-http</artifactId>-->
-        <!--</dependency>-->
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>dubbo-rpc-http</artifactId>
+        </dependency>
+
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>

dubbo-demo/dubbo-http-demo-consumer/src/main/java/com/alibaba/dubbo/demo/provider/HttpConsumer.java

+package com.alibaba.dubbo.demo.provider;
+
+import com.alibaba.dubbo.demo.HttpDemoService;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+public class HttpConsumer {
+
+    public static void main(String[] args) {
+        System.setProperty("java.net.preferIPv4Stack", "true");
+        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-consumer.xml"});
+        context.start();
+        HttpDemoService demoService = (HttpDemoService) context.getBean("demoService"); // get remote service proxy
+
+        while (true) {
+            try {
+                Thread.sleep(1000);
+
+                String hello = demoService.hello("world"); // call remote method
+                System.out.println(hello); // get result
+
+
+            } catch (Throwable throwable) {
+                throwable.printStackTrace();
+            }
+
+
+        }
+    }
+
+}

dubbo-demo/dubbo-http-demo-consumer/src/main/resources/META-INF/spring/dubbo-demo-provider.xml → dubbo-demo/dubbo-http-demo-consumer/src/main/resources/META-INF/spring/dubbo-demo-consumer.xml

@@ -21,21 +21,17 @@ limitations under the License.
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
        http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
 
-    <!-- provider's application name, used for tracing dependency relationship -->
-    <dubbo:application name="demo-provider"/>
-
-    <dubbo:provider delay="-1" retries="0" />
-
-    <dubbo:registry address="zookeeper://127.0.0.1:2181" />
-
-    <bean id="demoService" class="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>
-
-    <!-- declare the service interface to be exported -->
-    <dubbo:service interface="com.alibaba.dubbo.demo.HttpDemoService" ref="demoService">
-    </dubbo:service>
-
-    <!-- use dubbo protocol to export service on port 20880 -->
-    <dubbo:protocol name="http" port="8080" server="tomcat" />
-    <!--<dubbo:protocol id="pb" name="dubbo" port="20881"/>-->
+    <!-- consumer's application name, used for tracing dependency relationship (not a matching criterion),
+    don't set it same as provider -->
+    <dubbo:application name="demo-consumer" />
+
+    <!-- use multicast registry center to discover service -->
+    <!--<dubbo:registry address="multicast://224.5.6.7:1234"/>-->
+    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>
+
+    <!-- generate proxy for the remote service, then demoService can be used in the same way as the
+    local regular interface -->
+    <dubbo:reference id="demoService" check="false" interface="com.alibaba.dubbo.demo.HttpDemoService" >
+    </dubbo:reference>
 
 </beans>
\ No newline at end of file

dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/RpcContext.java

@@ -65,16 +65,27 @@ public class RpcContext {
 
     private final Map<String, String> attachments = new HashMap<String, String>();
     private final Map<String, Object> values = new HashMap<String, Object>();
+    /**
+     * 异步调用 Future
+     */
     private Future<?> future;
 
     private List<URL> urls;
-
+    /**
+     * URL 对象
+     */
     private URL url;
-
+    /**
+     * 方法名
+     */
     private String methodName;
-
+    /**
+     * 参数类型数组
+     */
     private Class<?>[] parameterTypes;
-
+    /**
+     * 参数值数组
+     */
     private Object[] arguments;
     /**
      * 服务消费者地址

dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/AbstractProtocol.java

@@ -75,6 +75,7 @@ public abstract class AbstractProtocol implements Protocol {
         return ProtocolUtils.serviceKey(port, serviceName, serviceVersion, serviceGroup);
     }
 
+    @Override
     public void destroy() {
         for (Invoker<?> invoker : invokers) {
             if (invoker != null) {

dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/AbstractProxyProtocol.java

@@ -32,11 +32,18 @@ import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
  * AbstractProxyProtocol
+ *
+ * Proxy 协议抽象类
  */
 public abstract class AbstractProxyProtocol extends AbstractProtocol {
 
+    /**
+     * 需要抛出的异常类集合，详见 {@link #refer(Class, URL)} 方法。
+     */
     private final List<Class<?>> rpcExceptions = new CopyOnWriteArrayList<Class<?>>();
-
+    /**
+     * ProxyFactory 对象
+     */
     private ProxyFactory proxyFactory;
 
     public AbstractProxyProtocol() {
@@ -60,18 +67,27 @@ public abstract class AbstractProxyProtocol extends AbstractProtocol {
         this.proxyFactory = proxyFactory;
     }
 
+    @Override
     @SuppressWarnings("unchecked")
     public <T> Exporter<T> export(final Invoker<T> invoker) throws RpcException {
+        // 获得服务键
         final String uri = serviceKey(invoker.getUrl());
+        // 获得 Exporter 对象。若已经暴露，直接返回。
         Exporter<T> exporter = (Exporter<T>) exporterMap.get(uri);
         if (exporter != null) {
             return exporter;
         }
+        // 执行暴露服务
         final Runnable runnable = doExport(proxyFactory.getProxy(invoker), invoker.getInterface(), invoker.getUrl());
+        // 创建 Exporter 对象
         exporter = new AbstractExporter<T>(invoker) {
+
+            @Override
             public void unexport() {
+                // 取消暴露
                 super.unexport();
                 exporterMap.remove(uri);
+                // 执行取消暴露的回调
                 if (runnable != null) {
                     try {
                         runnable.run();
@@ -80,18 +96,26 @@ public abstract class AbstractProxyProtocol extends AbstractProtocol {
                     }
                 }
             }
+
         };
+        // 添加到 Exporter 集合
         exporterMap.put(uri, exporter);
         return exporter;
     }
 
+    @Override
     public <T> Invoker<T> refer(final Class<T> type, final URL url) throws RpcException {
-        final Invoker<T> tagert = proxyFactory.getInvoker(doRefer(type, url), type, url);
+        // 执行引用服务
+        final Invoker<T> target = proxyFactory.getInvoker(doRefer(type, url), type, url);
+        // 创建 Invoker 对象
         Invoker<T> invoker = new AbstractInvoker<T>(type, url) {
+
             @Override
             protected Result doInvoke(Invocation invocation) throws Throwable {
                 try {
-                    Result result = tagert.invoke(invocation);
+                    // 调用
+                    Result result = target.invoke(invocation);
+                    // 若返回结果带有异常，并且需要抛出，则抛出异常。
                     Throwable e = result.getException();
                     if (e != null) {
                         for (Class<?> rpcException : rpcExceptions) {
@@ -102,15 +126,19 @@ public abstract class AbstractProxyProtocol extends AbstractProtocol {
                     }
                     return result;
                 } catch (RpcException e) {
+                    // 若是未知异常，获得异常对应的错误码
                     if (e.getCode() == RpcException.UNKNOWN_EXCEPTION) {
                         e.setCode(getErrorCode(e.getCause()));
                     }
                     throw e;
                 } catch (Throwable e) {
+                    // 抛出 RpcException 异常
                     throw getRpcException(type, url, invocation, e);
                 }
             }
+
         };
+        // 添加到 Invoker 集合。
         invokers.add(invoker);
         return invoker;
     }
@@ -130,12 +158,37 @@ public abstract class AbstractProxyProtocol extends AbstractProtocol {
         return NetUtils.getIpByHost(bindIp) + ":" + url.getParameter(Constants.BIND_PORT_KEY, url.getPort());
     }
 
+    /**
+     * 获得异常对应的错误码
+     *
+     * @param e 异常
+     * @return 错误码
+     */
     protected int getErrorCode(Throwable e) {
         return RpcException.UNKNOWN_EXCEPTION;
     }
 
+    /**
+     * 执行暴露，并返回取消暴露的回调 Runnable
+     *
+     * @param impl 服务 Proxy 对象
+     * @param type 服务接口
+     * @param url URL
+     * @param <T> 服务接口
+     * @return 消暴露的回调 Runnable
+     * @throws RpcException 当发生异常
+     */
     protected abstract <T> Runnable doExport(T impl, Class<T> type, URL url) throws RpcException;
 
+    /**
+     * 执行引用，并返回调用远程服务的 Service 对象
+     *
+     * @param type 服务接口
+     * @param url URL
+     * @param <T> 服务接口
+     * @return 调用远程服务的 Service 对象
+     * @throws RpcException 当发生异常
+     */
     protected abstract <T> T doRefer(Class<T> type, URL url) throws RpcException;
 
 }

dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/support/MockInvoker.java

@@ -54,7 +54,7 @@ final public class MockInvoker<T> implements Invoker<T> {
     }
 
     public static Object parseMockValue(String mock, Type[] returnTypes) throws Exception {
-        Object value = null;
+        Object value;
         if ("empty".equals(mock)) {
             value = ReflectUtils.getEmptyObject(returnTypes != null && returnTypes.length > 0 ? (Class<?>) returnTypes[0] : null);
         } else if ("null".equals(mock)) {

dubbo-rpc/dubbo-rpc-hessian/src/main/java/com/alibaba/dubbo/rpc/protocol/hessian/HessianProtocol.java

@@ -42,13 +42,26 @@ import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * http rpc support.
+ *
+ * Hessian 协议实现类
  */
 public class HessianProtocol extends AbstractProxyProtocol {
 
+    /**
+     * Http 服务器集合
+     *
+     * key：ip:port
+     */
     private final Map<String, HttpServer> serverMap = new ConcurrentHashMap<String, HttpServer>();
-
+    /**
+     * Spring HttpInvokerServiceExporter 集合
+     *
+     * key：path 服务名
+     */
     private final Map<String, HessianSkeleton> skeletonMap = new ConcurrentHashMap<String, HessianSkeleton>();
-
+    /**
+     * HttpBinder$Adaptive 对象
+     */
     private HttpBinder httpBinder;
 
     public HessianProtocol() {
@@ -63,16 +76,21 @@ public class HessianProtocol extends AbstractProxyProtocol {
         return 80;
     }
 
+    @Override
     protected <T> Runnable doExport(T impl, Class<T> type, URL url) throws RpcException {
+        // 获得服务器地址
         String addr = getAddr(url);
+        // 获得 HttpServer 对象。若不存在，进行创建。
         HttpServer server = serverMap.get(addr);
         if (server == null) {
-            server = httpBinder.bind(url, new HessianHandler());
+            server = httpBinder.bind(url, new HessianHandler()); // HessianHandler
             serverMap.put(addr, server);
         }
+        // 添加到 skeletonMap 中
         final String path = url.getAbsolutePath();
         HessianSkeleton skeleton = new HessianSkeleton(impl, type);
         skeletonMap.put(path, skeleton);
+        // 返回取消暴露的回调 Runnable
         return new Runnable() {
             public void run() {
                 skeletonMap.remove(path);
@@ -80,21 +98,27 @@ public class HessianProtocol extends AbstractProxyProtocol {
         };
     }
 
+    @Override
     @SuppressWarnings("unchecked")
     protected <T> T doRefer(Class<T> serviceType, URL url) throws RpcException {
+        // 创建 HessianProxyFactory 对象
         HessianProxyFactory hessianProxyFactory = new HessianProxyFactory();
+        // 创建连接器工厂为 HttpClientConnectionFactory 对象，即 Apache HttpClient
         String client = url.getParameter(Constants.CLIENT_KEY, Constants.DEFAULT_HTTP_CLIENT);
         if ("httpclient".equals(client)) {
             hessianProxyFactory.setConnectionFactory(new HttpClientConnectionFactory());
         } else if (client != null && client.length() > 0 && !Constants.DEFAULT_HTTP_CLIENT.equals(client)) {
             throw new IllegalStateException("Unsupported http protocol client=\"" + client + "\"!");
         }
+        // 设置超时时间
         int timeout = url.getParameter(Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT);
         hessianProxyFactory.setConnectTimeout(timeout);
         hessianProxyFactory.setReadTimeout(timeout);
+        // 创建 Service Proxy 对象
         return (T) hessianProxyFactory.create(serviceType, url.setProtocol("http").toJavaURL(), Thread.currentThread().getContextClassLoader());
     }
 
+    @Override
     protected int getErrorCode(Throwable e) {
         if (e instanceof HessianConnectionException) {
             if (e.getCause() != null) {
@@ -110,8 +134,11 @@ public class HessianProtocol extends AbstractProxyProtocol {
         return super.getErrorCode(e);
     }
 
+    @Override
     public void destroy() {
+        // 销毁
         super.destroy();
+        // 销毁 HttpServer
         for (String key : new ArrayList<String>(serverMap.keySet())) {
             HttpServer server = serverMap.remove(key);
             if (server != null) {
@@ -129,12 +156,16 @@ public class HessianProtocol extends AbstractProxyProtocol {
 
     private class HessianHandler implements HttpHandler {
 
+        @Override
         public void handle(HttpServletRequest request, HttpServletResponse response)
                 throws IOException, ServletException {
             String uri = request.getRequestURI();
+            // 获得 HessianSkeleton 对象
             HessianSkeleton skeleton = skeletonMap.get(uri);
+            // 必须是 POST 请求
             if (!request.getMethod().equalsIgnoreCase("POST")) {
                 response.setStatus(500);
+            // 执行调用
             } else {
                 RpcContext.getContext().setRemoteAddress(request.getRemoteAddr(), request.getRemotePort());
                 try {

dubbo-rpc/dubbo-rpc-hessian/src/main/java/com/alibaba/dubbo/rpc/protocol/hessian/HttpClientConnection.java

@@ -34,6 +34,9 @@ import java.net.URL;
  */
 public class HttpClientConnection implements HessianConnection {
 
+    /**
+     * Apache HttpClient
+     */
     private final HttpClient httpClient;
 
     private final ByteArrayOutputStream output;
@@ -48,35 +51,43 @@ public class HttpClientConnection implements HessianConnection {
         this.request = new HttpPost(url.toString());
     }
 
+    @Override
     public void addHeader(String key, String value) {
         request.addHeader(new BasicHeader(key, value));
     }
 
+    @Override
     public OutputStream getOutputStream() throws IOException {
         return output;
     }
 
+    @Override
     public void sendRequest() throws IOException {
         request.setEntity(new ByteArrayEntity(output.toByteArray()));
         this.response = httpClient.execute(request);
     }
 
+    @Override
     public int getStatusCode() {
         return response == null || response.getStatusLine() == null ? 0 : response.getStatusLine().getStatusCode();
     }
 
+    @Override
     public String getStatusMessage() {
         return response == null || response.getStatusLine() == null ? null : response.getStatusLine().getReasonPhrase();
     }
 
+    @Override
     public String getContentEncoding() {
         return (response == null || response.getEntity() == null || response.getEntity().getContentEncoding() == null) ? null : response.getEntity().getContentEncoding().getValue();
     }
 
+    @Override
     public InputStream getInputStream() throws IOException {
         return response == null || response.getEntity() == null ? null : response.getEntity().getContent();
     }
 
+    @Override
     public void close() throws IOException {
         HttpPost request = this.request;
         if (request != null) {
@@ -84,6 +95,7 @@ public class HttpClientConnection implements HessianConnection {
         }
     }
 
+    @Override
     public void destroy() throws IOException {
     }
 

dubbo-rpc/dubbo-rpc-hessian/src/main/java/com/alibaba/dubbo/rpc/protocol/hessian/HttpClientConnectionFactory.java

@@ -23,7 +23,6 @@ import org.apache.http.client.HttpClient;
 import org.apache.http.impl.client.DefaultHttpClient;
 import org.apache.http.params.HttpConnectionParams;
 
-import java.io.IOException;
 import java.net.URL;
 
 /**
@@ -31,15 +30,20 @@ import java.net.URL;
  */
 public class HttpClientConnectionFactory implements HessianConnectionFactory {
 
+    /**
+     * Apache HttpClient
+     */
     private final HttpClient httpClient = new DefaultHttpClient();
 
+    @Override
     public void setHessianProxyFactory(HessianProxyFactory factory) {
         HttpConnectionParams.setConnectionTimeout(httpClient.getParams(), (int) factory.getConnectTimeout());
         HttpConnectionParams.setSoTimeout(httpClient.getParams(), (int) factory.getReadTimeout());
     }
 
-    public HessianConnection open(URL url) throws IOException {
-        return new HttpClientConnection(httpClient, url);
+    @Override
+    public HessianConnection open(URL url) {
+        return new HttpClientConnection(httpClient, url); // HttpClientConnection
     }
 
 }
\ No newline at end of file

dubbo-rpc/dubbo-rpc-http/src/main/java/com/alibaba/dubbo/rpc/protocol/http/HttpProtocol.java

@@ -42,15 +42,30 @@ import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * HttpProtocol
+ *
+ * HTTP 协议实现类
  */
 public class HttpProtocol extends AbstractProxyProtocol {
 
+    /**
+     * 默认服务器端口
+     */
     public static final int DEFAULT_PORT = 80;
-
+    /**
+     * Http 服务器集合
+     *
+     * key：ip:port
+     */
     private final Map<String, HttpServer> serverMap = new ConcurrentHashMap<String, HttpServer>();
-
+    /**
+     * Spring HttpInvokerServiceExporter 集合
+     *
+     * key：path 服务名
+     */
     private final Map<String, HttpInvokerServiceExporter> skeletonMap = new ConcurrentHashMap<String, HttpInvokerServiceExporter>();
-
+    /**
+     * HttpBinder$Adaptive 对象
+     */
     private HttpBinder httpBinder;
 
     public HttpProtocol() {
@@ -65,13 +80,17 @@ public class HttpProtocol extends AbstractProxyProtocol {
         return DEFAULT_PORT;
     }
 
+    @Override
     protected <T> Runnable doExport(final T impl, Class<T> type, URL url) throws RpcException {
+        // 获得服务器地址
         String addr = getAddr(url);
+        // 获得 HttpServer 对象。若不存在，进行创建。
         HttpServer server = serverMap.get(addr);
         if (server == null) {
-            server = httpBinder.bind(url, new InternalHandler());
+            server = httpBinder.bind(url, new InternalHandler()); // InternalHandler
             serverMap.put(addr, server);
         }
+        // 创建 HttpInvokerServiceExporter 对象
         final HttpInvokerServiceExporter httpServiceExporter = new HttpInvokerServiceExporter();
         httpServiceExporter.setServiceInterface(type);
         httpServiceExporter.setService(impl);
@@ -80,8 +99,10 @@ public class HttpProtocol extends AbstractProxyProtocol {
         } catch (Exception e) {
             throw new RpcException(e.getMessage(), e);
         }
+        // 添加到 skeletonMap 中
         final String path = url.getAbsolutePath();
         skeletonMap.put(path, httpServiceExporter);
+        // 返回取消暴露的回调 Runnable
         return new Runnable() {
             public void run() {
                 skeletonMap.remove(path);
@@ -89,11 +110,14 @@ public class HttpProtocol extends AbstractProxyProtocol {
         };
     }
 
+    @Override
     @SuppressWarnings("unchecked")
     protected <T> T doRefer(final Class<T> serviceType, final URL url) throws RpcException {
+        // 创建 HttpInvokerProxyFactoryBean 对象
         final HttpInvokerProxyFactoryBean httpProxyFactoryBean = new HttpInvokerProxyFactoryBean();
         httpProxyFactoryBean.setServiceUrl(url.toIdentityString());
         httpProxyFactoryBean.setServiceInterface(serviceType);
+        // 创建执行器 SimpleHttpInvokerRequestExecutor 对象
         String client = url.getParameter(Constants.CLIENT_KEY);
         if (client == null || client.length() == 0 || "simple".equals(client)) {
             SimpleHttpInvokerRequestExecutor httpInvokerRequestExecutor = new SimpleHttpInvokerRequestExecutor() {
@@ -105,6 +129,7 @@ public class HttpProtocol extends AbstractProxyProtocol {
                 }
             };
             httpProxyFactoryBean.setHttpInvokerRequestExecutor(httpInvokerRequestExecutor);
+        // 创建执行器 HttpComponentsHttpInvokerRequestExecutor 对象
         } else if ("commons".equals(client)) {
             HttpComponentsHttpInvokerRequestExecutor httpInvokerRequestExecutor = new HttpComponentsHttpInvokerRequestExecutor();
             httpInvokerRequestExecutor.setReadTimeout(url.getParameter(Constants.CONNECT_TIMEOUT_KEY, Constants.DEFAULT_CONNECT_TIMEOUT));
@@ -113,9 +138,12 @@ public class HttpProtocol extends AbstractProxyProtocol {
             throw new IllegalStateException("Unsupported http protocol client " + client + ", only supported: simple, commons");
         }
         httpProxyFactoryBean.afterPropertiesSet();
+        // 返回 HttpInvokerProxyFactoryBean 对象
         return (T) httpProxyFactoryBean.getObject();
     }
 
+    @Override
+    @SuppressWarnings("Duplicates")
     protected int getErrorCode(Throwable e) {
         if (e instanceof RemoteAccessException) {
             e = e.getCause();
@@ -135,12 +163,15 @@ public class HttpProtocol extends AbstractProxyProtocol {
 
     private class InternalHandler implements HttpHandler {
 
-        public void handle(HttpServletRequest request, HttpServletResponse response)
-                throws IOException, ServletException {
+        @Override
+        public void handle(HttpServletRequest request, HttpServletResponse response) throws ServletException {
             String uri = request.getRequestURI();
+            // 获得 HttpInvokerServiceExporter 对象
             HttpInvokerServiceExporter skeleton = skeletonMap.get(uri);
+            // 必须是 POST 请求
             if (!request.getMethod().equalsIgnoreCase("POST")) {
                 response.setStatus(500);
+            // 执行调用
             } else {
                 RpcContext.getContext().setRemoteAddress(request.getRemoteAddr(), request.getRemotePort());
                 try {

dubbo-rpc/dubbo-rpc-memcached/src/main/java/com/alibaba/dubbo/rpc/protocol/memcached/MemcachedProtocol.java

@@ -49,12 +49,15 @@ public class MemcachedProtocol extends AbstractProtocol {
         return DEFAULT_PORT;
     }
 
+    @Override
     public <T> Exporter<T> export(final Invoker<T> invoker) throws RpcException {
         throw new UnsupportedOperationException("Unsupported export memcached service. url: " + invoker.getUrl());
     }
 
+    @Override
     public <T> Invoker<T> refer(final Class<T> type, final URL url) throws RpcException {
         try {
+            // 创建 MemcachedClient 对象
             String address = url.getAddress();
             String backup = url.getParameter(Constants.BACKUP_KEY);
             if (backup != null && backup.length() > 0) {
@@ -62,30 +65,38 @@ public class MemcachedProtocol extends AbstractProtocol {
             }
             MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses(address));
             final MemcachedClient memcachedClient = builder.build();
+
+            // 处理方法名的映射
             final int expiry = url.getParameter("expiry", 0);
             final String get = url.getParameter("get", "get");
             final String set = url.getParameter("set", Map.class.equals(type) ? "put" : "set");
             final String delete = url.getParameter("delete", Map.class.equals(type) ? "remove" : "delete");
             return new AbstractInvoker<T>(type, url) {
+
+                @Override
                 protected Result doInvoke(Invocation invocation) throws Throwable {
                     try {
+                        // Memcached get 指令
                         if (get.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 1) {
                                 throw new IllegalArgumentException("The memcached get method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
                             return new RpcResult(memcachedClient.get(String.valueOf(invocation.getArguments()[0])));
+                        // Memcached set 指令
                         } else if (set.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 2) {
                                 throw new IllegalArgumentException("The memcached set method arguments mismatch, must be two arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
                             memcachedClient.set(String.valueOf(invocation.getArguments()[0]), expiry, invocation.getArguments()[1]);
                             return new RpcResult();
+                        // Memcached delele 指令
                         } else if (delete.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 1) {
                                 throw new IllegalArgumentException("The memcached delete method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
                             memcachedClient.delete(String.valueOf(invocation.getArguments()[0]));
                             return new RpcResult();
+                        // 不支持的指令，抛出异常
                         } else {
                             throw new UnsupportedOperationException("Unsupported method " + invocation.getMethodName() + " in memcached service.");
                         }
@@ -100,14 +111,18 @@ public class MemcachedProtocol extends AbstractProtocol {
                     }
                 }
 
+                @Override
                 public void destroy() {
+                    // 标记销毁
                     super.destroy();
+                    // 关闭 MemcachedClient
                     try {
                         memcachedClient.shutdown();
                     } catch (Throwable e) {
                         logger.warn(e.getMessage(), e);
                     }
                 }
+
             };
         } catch (Throwable t) {
             throw new RpcException("Failed to refer memcached service. interface: " + type.getName() + ", url: " + url + ", cause: " + t.getMessage(), t);

dubbo-rpc/dubbo-rpc-redis/src/main/java/com/alibaba/dubbo/rpc/protocol/redis/RedisProtocol.java

@@ -56,6 +56,7 @@ public class RedisProtocol extends AbstractProtocol {
         return DEFAULT_PORT;
     }
 
+    @Override
     public <T> Exporter<T> export(final Invoker<T> invoker) throws RpcException {
         throw new UnsupportedOperationException("Unsupported export redis service. url: " + invoker.getUrl());
     }
@@ -64,8 +65,10 @@ public class RedisProtocol extends AbstractProtocol {
         return ExtensionLoader.getExtensionLoader(Serialization.class).getExtension(url.getParameter(Constants.SERIALIZATION_KEY, "java"));
     }
 
+    @Override
     public <T> Invoker<T> refer(final Class<T> type, final URL url) throws RpcException {
         try {
+            // 创建 GenericObjectPoolConfig 对象，设置配置
             GenericObjectPoolConfig config = new GenericObjectPoolConfig();
             config.setTestOnBorrow(url.getParameter("test.on.borrow", true));
             config.setTestOnReturn(url.getParameter("test.on.return", false));
@@ -86,46 +89,64 @@ public class RedisProtocol extends AbstractProtocol {
                 config.setTimeBetweenEvictionRunsMillis(url.getParameter("time.between.eviction.runs.millis", 0));
             if (url.getParameter("min.evictable.idle.time.millis", 0) > 0)
                 config.setMinEvictableIdleTimeMillis(url.getParameter("min.evictable.idle.time.millis", 0));
+            // 创建 JedisPool 对象
             final JedisPool jedisPool = new JedisPool(config, url.getHost(), url.getPort(DEFAULT_PORT),
                     url.getParameter(Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT));
+
+            // 处理方法名的映射
             final int expiry = url.getParameter("expiry", 0);
             final String get = url.getParameter("get", "get");
             final String set = url.getParameter("set", Map.class.equals(type) ? "put" : "set");
             final String delete = url.getParameter("delete", Map.class.equals(type) ? "remove" : "delete");
+
+            // 创建 Invoker 对象
             return new AbstractInvoker<T>(type, url) {
-                protected Result doInvoke(Invocation invocation) throws Throwable {
+
+                @Override
+                protected Result doInvoke(Invocation invocation) {
                     Jedis resource = null;
                     try {
+                        // 获得 Redis Resource
                         resource = jedisPool.getResource();
-
+                        // Redis get 指令
                         if (get.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 1) {
                                 throw new IllegalArgumentException("The redis get method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
+                            // 获得值
                             byte[] value = resource.get(String.valueOf(invocation.getArguments()[0]).getBytes());
                             if (value == null) {
                                 return new RpcResult();
                             }
+                            // 反序列化
                             ObjectInput oin = getSerialization(url).deserialize(url, new ByteArrayInputStream(value));
+                            // 返回结果
                             return new RpcResult(oin.readObject());
+                        // Redis set/put 指令
                         } else if (set.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 2) {
                                 throw new IllegalArgumentException("The redis set method arguments mismatch, must be two arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
+                            // 序列化
                             byte[] key = String.valueOf(invocation.getArguments()[0]).getBytes();
                             ByteArrayOutputStream output = new ByteArrayOutputStream();
                             ObjectOutput value = getSerialization(url).serialize(url, output);
                             value.writeObject(invocation.getArguments()[1]);
+                            // 设置值
                             resource.set(key, output.toByteArray());
                             if (expiry > 1000) {
                                 resource.expire(key, expiry / 1000);
                             }
+                            // 返回结果
                             return new RpcResult();
+                        // Redis remote/delete 指令
                         } else if (delete.equals(invocation.getMethodName())) {
                             if (invocation.getArguments().length != 1) {
                                 throw new IllegalArgumentException("The redis delete method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
                             }
+                            // 删除值
                             resource.del(String.valueOf(invocation.getArguments()[0]).getBytes());
+                            // 返回结果
                             return new RpcResult();
                         } else {
                             throw new UnsupportedOperationException("Unsupported method " + invocation.getMethodName() + " in redis service.");
@@ -141,6 +162,7 @@ public class RedisProtocol extends AbstractProtocol {
                         }
                         throw re;
                     } finally {
+                        // 归还 Redis Resource
                         if (resource != null) {
                             try {
                                 jedisPool.returnResource(resource);
@@ -151,14 +173,18 @@ public class RedisProtocol extends AbstractProtocol {
                     }
                 }
 
+                @Override
                 public void destroy() {
+                    // 标记销毁
                     super.destroy();
+                    // 销毁 Redis Pool
                     try {
                         jedisPool.destroy();
                     } catch (Throwable e) {
                         logger.warn(e.getMessage(), e);
                     }
                 }
+
             };
         } catch (Throwable t) {
             throw new RpcException("Failed to refer redis service. interface: " + type.getName() + ", url: " + url + ", cause: " + t.getMessage(), t);

dubbo-rpc/dubbo-rpc-rmi/src/main/java/com/alibaba/dubbo/rpc/protocol/rmi/RmiProtocol.java

@@ -35,9 +35,14 @@ import java.rmi.RemoteException;
 
 /**
  * RmiProtocol.
+ *
+ * RMI 协议实现类
  */
 public class RmiProtocol extends AbstractProxyProtocol {
 
+    /**
+     * 默认端口
+     */
     public static final int DEFAULT_PORT = 1099;
 
     public RmiProtocol() {
@@ -48,7 +53,9 @@ public class RmiProtocol extends AbstractProxyProtocol {
         return DEFAULT_PORT;
     }
 
+    @Override
     protected <T> Runnable doExport(final T impl, Class<T> type, URL url) throws RpcException {
+        // 创建 RmiServiceExporter 对象
         final RmiServiceExporter rmiServiceExporter = new RmiServiceExporter();
         rmiServiceExporter.setRegistryPort(url.getPort());
         rmiServiceExporter.setServiceName(url.getPath());
@@ -59,6 +66,7 @@ public class RmiProtocol extends AbstractProxyProtocol {
         } catch (RemoteException e) {
             throw new RpcException(e.getMessage(), e);
         }
+        // 返回取消暴露的回调 Runnable
         return new Runnable() {
             public void run() {
                 try {
@@ -70,10 +78,13 @@ public class RmiProtocol extends AbstractProxyProtocol {
         };
     }
 
+    @Override
     @SuppressWarnings("unchecked")
     protected <T> T doRefer(final Class<T> serviceType, final URL url) throws RpcException {
+        // 创建 RmiProxyFactoryBean 对象
         final RmiProxyFactoryBean rmiProxyFactoryBean = new RmiProxyFactoryBean();
         // RMI needs extra parameter since it uses customized remote invocation object
+        // RMI传输时使用自定义的远程执行对象，从而传递额外的参数
         if (url.getParameter(Constants.DUBBO_VERSION_KEY, Version.getVersion()).equals(Version.getVersion())) {
             // Check dubbo version on provider, this feature only support
             rmiProxyFactoryBean.setRemoteInvocationFactory(new RemoteInvocationFactory() {
@@ -82,15 +93,18 @@ public class RmiProtocol extends AbstractProxyProtocol {
                 }
             });
         }
+        // 设置相关参数
         rmiProxyFactoryBean.setServiceUrl(url.toIdentityString());
         rmiProxyFactoryBean.setServiceInterface(serviceType);
         rmiProxyFactoryBean.setCacheStub(true);
         rmiProxyFactoryBean.setLookupStubOnStartup(true);
         rmiProxyFactoryBean.setRefreshStubOnConnectFailure(true);
         rmiProxyFactoryBean.afterPropertiesSet();
+        // 创建 Service Proxy 对象
         return (T) rmiProxyFactoryBean.getObject();
     }
 
+    @Override
     protected int getErrorCode(Throwable e) {
         if (e instanceof RemoteAccessException) {
             e = e.getCause();

dubbo-rpc/dubbo-rpc-rmi/src/main/java/com/alibaba/dubbo/rpc/protocol/rmi/RmiRemoteInvocation.java

@@ -25,11 +25,15 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class RmiRemoteInvocation extends RemoteInvocation {
+
     private static final long serialVersionUID = 1L;
+
     private static final String dubboAttachmentsAttrName = "dubbo.attachments";
 
     /**
      * executed on consumer side
+     *
+     * 构造将在消费端执行
      */
     public RmiRemoteInvocation(MethodInvocation methodInvocation) {
         super(methodInvocation);
@@ -40,6 +44,8 @@ public class RmiRemoteInvocation extends RemoteInvocation {
      * Need to restore context on provider side (Though context will be overridden by Invocation's attachment
      * when ContextFilter gets executed, we will restore the attachment when Invocation is constructed, check more
      * from {@link com.alibaba.dubbo.rpc.proxy.InvokerInvocationHandler}
+     *
+     * 服务端执行时，重新放入上下文（虽然这时上下文在ContextFilter执行时将被Invocation的attachments覆盖，我们在Invocation构造时还原attachments, see InvokerInvocationHandler）
      */
     @SuppressWarnings("unchecked")
     @Override

dubbo-rpc/dubbo-rpc-webservice/src/main/java/com/alibaba/dubbo/rpc/protocol/webservice/WebServiceProtocol.java

@@ -50,17 +50,33 @@ import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * WebServiceProtocol.
+ *
+ * WebService 协议实现类
  */
 public class WebServiceProtocol extends AbstractProxyProtocol {
 
+    /**
+     * 默认服务器端口
+     */
     public static final int DEFAULT_PORT = 80;
-
+    /**
+     * Http 服务器集合
+     *
+     * key：ip:port
+     */
     private final Map<String, HttpServer> serverMap = new ConcurrentHashMap<String, HttpServer>();
-
+    /**
+     * 《我眼中的CXF之Bus》http://jnn.iteye.com/blog/94746
+     * 《CXF BUS》https://blog.csdn.net/chen_fly2011/article/details/56664908
+     */
     private final ExtensionManagerBus bus = new ExtensionManagerBus();
-
+    /**
+     *
+     */
     private final HTTPTransportFactory transportFactory = new HTTPTransportFactory();
-
+    /**
+     * HttpBinder$Adaptive 对象
+     */
     private HttpBinder httpBinder;
 
     public WebServiceProtocol() {
@@ -76,13 +92,17 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
         return DEFAULT_PORT;
     }
 
+    @Override
     protected <T> Runnable doExport(T impl, Class<T> type, URL url) throws RpcException {
+        // 获得服务器地址
         String addr = getAddr(url);
+        // 获得 HttpServer 对象。若不存在，进行创建。
         HttpServer httpServer = serverMap.get(addr);
         if (httpServer == null) {
-            httpServer = httpBinder.bind(url, new WebServiceHandler());
+            httpServer = httpBinder.bind(url, new WebServiceHandler()); // WebServiceHandler
             serverMap.put(addr, httpServer);
         }
+        // 创建 ServerFactoryBean 对象
         final ServerFactoryBean serverFactoryBean = new ServerFactoryBean();
         serverFactoryBean.setAddress(url.getAbsolutePath());
         serverFactoryBean.setServiceClass(type);
@@ -90,6 +110,7 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
         serverFactoryBean.setBus(bus);
         serverFactoryBean.setDestinationFactory(transportFactory);
         serverFactoryBean.create();
+        // 返回取消暴露的回调 Runnable
         return new Runnable() {
             public void run() {
                 serverFactoryBean.destroy();
@@ -97,13 +118,17 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
         };
     }
 
+    @Override
     @SuppressWarnings("unchecked")
     protected <T> T doRefer(final Class<T> serviceType, final URL url) throws RpcException {
+        // 创建 ClientProxyFactoryBean 对象
         ClientProxyFactoryBean proxyFactoryBean = new ClientProxyFactoryBean();
         proxyFactoryBean.setAddress(url.setProtocol("http").toIdentityString());
         proxyFactoryBean.setServiceClass(serviceType);
         proxyFactoryBean.setBus(bus);
+        // 创建 Service Proxy 对象
         T ref = (T) proxyFactoryBean.create();
+        // 设置超时相关属性
         Client proxy = ClientProxy.getClient(ref);
         HTTPConduit conduit = (HTTPConduit) proxy.getConduit();
         HTTPClientPolicy policy = new HTTPClientPolicy();
@@ -113,6 +138,7 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
         return ref;
     }
 
+    @Override
     protected int getErrorCode(Throwable e) {
         if (e instanceof Fault) {
             e = e.getCause();
@@ -129,7 +155,9 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
 
         private volatile ServletController servletController;
 
+        @Override
         public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
+            // 创建 ServletController 对象，设置使用 DispatcherServlet 。
             if (servletController == null) {
                 HttpServlet httpServlet = DispatcherServlet.getInstance();
                 if (httpServlet == null) {
@@ -142,7 +170,9 @@ public class WebServiceProtocol extends AbstractProxyProtocol {
                     }
                 }
             }
+            // 设置调用方地址
             RpcContext.getContext().setRemoteAddress(request.getRemoteAddr(), request.getRemotePort());
+            // 执行调用
             servletController.invoke(request, response);
         }